diff --git a/.gitignore b/.gitignore
index 246f2c4bdaf7d..aeb238e4e07a0 100644
--- a/.gitignore
+++ b/.gitignore
@@ -143,3 +143,7 @@ javascript/selenium-webdriver/.vscode/settings.json
 dotnet-bin
 .metadata/
 .npmrc
+
+# HAR files and directories generated during tests
+*.har
+selenium-har-*/
diff --git a/dotnet/src/webdriver/BiDi/Network/Har/BiDi.HarExtensions.cs b/dotnet/src/webdriver/BiDi/Network/Har/BiDi.HarExtensions.cs
new file mode 100644
index 0000000000000..5499681e0963c
--- /dev/null
+++ b/dotnet/src/webdriver/BiDi/Network/Har/BiDi.HarExtensions.cs
@@ -0,0 +1,73 @@
+// <copyright file="BiDi.HarExtensions.cs" company="Selenium Committers">
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+// </copyright>
+
+using System;
+using System.Threading.Tasks;
+
+namespace OpenQA.Selenium.BiDi.Network.Har;
+
+/// <summary>
+/// Extension methods for BiDi class to capture network traffic as HAR.
+/// </summary>
+public static class BiDiHarExtensions
+{
+    /// <summary>
+    /// Records network traffic and returns a HAR recorder that can be used to save the recorded traffic.
+    /// </summary>
+    /// <param name="bidi">The BiDi instance.</param>
+    /// <param name="options">Optional configuration options.</param>
+    /// <returns>A task that represents the asynchronous operation and returns a IHarRecorder.</returns>
+    public static async Task<IHarRecorder> RecordHarAsync(this BiDi bidi, HarRecordingOptions? options = null)
+    {
+        if (bidi is null) throw new ArgumentNullException(nameof(bidi));
+
+        var recorder = new HarRecorder(bidi, options ?? new HarRecordingOptions());
+        await recorder.StartAsync().ConfigureAwait(false);
+        return recorder;
+    }
+}
+
+/// <summary>
+/// Options for HAR recording.
+/// </summary>
+public sealed class HarRecordingOptions
+{
+    /// <summary>
+    /// Gets or sets the browser name to include in the HAR file.
+    /// </summary>
+    public string? BrowserName { get; set; }
+
+    /// <summary>
+    /// Gets or sets the browser version to include in the HAR file.
+    /// </summary>
+    public string? BrowserVersion { get; set; }
+}
+
+/// <summary>
+/// Interface for recording network traffic and saving it as HAR format.
+/// </summary>
+public interface IHarRecorder : IAsyncDisposable
+{
+    /// <summary>
+    /// Saves the captured network traffic to a HAR file.
+    /// </summary>
+    /// <param name="filePath">The path where the HAR file should be saved.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    Task SaveAsync(string filePath);
+}
diff --git a/dotnet/src/webdriver/BiDi/Network/Har/HarEntry.cs b/dotnet/src/webdriver/BiDi/Network/Har/HarEntry.cs
new file mode 100644
index 0000000000000..e633874fca361
--- /dev/null
+++ b/dotnet/src/webdriver/BiDi/Network/Har/HarEntry.cs
@@ -0,0 +1,469 @@
+// <copyright file="HarEntry.cs" company="Selenium Committers">
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+// </copyright>
+
+using System.Collections.Generic;
+
+namespace OpenQA.Selenium.BiDi.Network.Har;
+
+/// <summary>
+/// Represents a HAR entry object containing request and response information.
+/// </summary>
+public sealed class HarEntry
+{
+    /// <summary>
+    /// Gets or sets the reference to the parent page.
+    /// </summary>
+    public string? Pageref { get; set; }
+
+    /// <summary>
+    /// Gets or sets the date and time stamp of the request start.
+    /// </summary>
+    public string StartedDateTime { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the total elapsed time in milliseconds.
+    /// </summary>
+    public double Time { get; set; }
+
+    /// <summary>
+    /// Gets or sets the request information.
+    /// </summary>
+    public HarRequest Request { get; set; } = new HarRequest();
+
+    /// <summary>
+    /// Gets or sets the response information.
+    /// </summary>
+    public HarResponse Response { get; set; } = new HarResponse();
+
+    /// <summary>
+    /// Gets or sets the cache information.
+    /// </summary>
+    public HarCache Cache { get; set; } = new HarCache();
+
+    /// <summary>
+    /// Gets or sets the timing information.
+    /// </summary>
+    public HarTimings Timings { get; set; } = new HarTimings();
+
+    /// <summary>
+    /// Gets or sets the server IP address.
+    /// </summary>
+    public string? ServerIPAddress { get; set; }
+
+    /// <summary>
+    /// Gets or sets the connection information.
+    /// </summary>
+    public string? Connection { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR request object.
+/// </summary>
+public sealed class HarRequest
+{
+    /// <summary>
+    /// Gets or sets the request method.
+    /// </summary>
+    public string Method { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the absolute URL of the request.
+    /// </summary>
+    public string Url { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the request HTTP version.
+    /// </summary>
+    public string HttpVersion { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the list of cookie objects.
+    /// </summary>
+    public List<HarCookie> Cookies { get; set; } = new List<HarCookie>();
+
+    /// <summary>
+    /// Gets or sets the list of header objects.
+    /// </summary>
+    public List<HarHeader> Headers { get; set; } = new List<HarHeader>();
+
+    /// <summary>
+    /// Gets or sets the list of query parameter objects.
+    /// </summary>
+    public List<HarQueryParam> QueryString { get; set; } = new List<HarQueryParam>();
+
+    /// <summary>
+    /// Gets or sets the posted data information.
+    /// </summary>
+    public HarPostData? PostData { get; set; }
+
+    /// <summary>
+    /// Gets or sets the total number of bytes from the start of the HTTP request message.
+    /// </summary>
+    public long HeadersSize { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the size of the request body in bytes.
+    /// </summary>
+    public long BodySize { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR response object.
+/// </summary>
+public sealed class HarResponse
+{
+    /// <summary>
+    /// Gets or sets the response status code.
+    /// </summary>
+    public int Status { get; set; }
+
+    /// <summary>
+    /// Gets or sets the response status description.
+    /// </summary>
+    public string StatusText { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the response HTTP version.
+    /// </summary>
+    public string HttpVersion { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the list of cookie objects.
+    /// </summary>
+    public List<HarCookie> Cookies { get; set; } = new List<HarCookie>();
+
+    /// <summary>
+    /// Gets or sets the list of header objects.
+    /// </summary>
+    public List<HarHeader> Headers { get; set; } = new List<HarHeader>();
+
+    /// <summary>
+    /// Gets or sets the response body content.
+    /// </summary>
+    public HarContent Content { get; set; } = new HarContent();
+
+    /// <summary>
+    /// Gets or sets the redirection target URL from the Location response header.
+    /// </summary>
+    public string RedirectURL { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the total number of bytes from the start of the HTTP response message.
+    /// </summary>
+    public long HeadersSize { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the size of the received response body in bytes.
+    /// </summary>
+    public long BodySize { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR cookie object.
+/// </summary>
+public sealed class HarCookie
+{
+    /// <summary>
+    /// Gets or sets the cookie name.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the cookie value.
+    /// </summary>
+    public string Value { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the path pertaining to the cookie.
+    /// </summary>
+    public string? Path { get; set; }
+
+    /// <summary>
+    /// Gets or sets the host of the cookie.
+    /// </summary>
+    public string? Domain { get; set; }
+
+    /// <summary>
+    /// Gets or sets the cookie expiration time.
+    /// </summary>
+    public string? Expires { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the cookie is HTTP only.
+    /// </summary>
+    public bool? HttpOnly { get; set; }
+
+    /// <summary>
+    /// Gets or sets a value indicating whether the cookie is secure.
+    /// </summary>
+    public bool? Secure { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR header object.
+/// </summary>
+public sealed class HarHeader
+{
+    /// <summary>
+    /// Gets or sets the header name.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the header value.
+    /// </summary>
+    public string Value { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR query parameter object.
+/// </summary>
+public sealed class HarQueryParam
+{
+    /// <summary>
+    /// Gets or sets the query parameter name.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the query parameter value.
+    /// </summary>
+    public string Value { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents HAR post data information.
+/// </summary>
+public sealed class HarPostData
+{
+    /// <summary>
+    /// Gets or sets the MIME type of the posted data.
+    /// </summary>
+    public string MimeType { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the list of posted parameters.
+    /// </summary>
+    public List<HarPostParam>? Params { get; set; }
+
+    /// <summary>
+    /// Gets or sets the plain text posted data.
+    /// </summary>
+    public string? Text { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR post parameter object.
+/// </summary>
+public sealed class HarPostParam
+{
+    /// <summary>
+    /// Gets or sets the parameter name.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the parameter value.
+    /// </summary>
+    public string? Value { get; set; }
+
+    /// <summary>
+    /// Gets or sets the name of the uploaded file.
+    /// </summary>
+    public string? FileName { get; set; }
+
+    /// <summary>
+    /// Gets or sets the content type of the uploaded file.
+    /// </summary>
+    public string? ContentType { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents HAR content information.
+/// </summary>
+public sealed class HarContent
+{
+    /// <summary>
+    /// Gets or sets the length of the content in bytes.
+    /// </summary>
+    public long Size { get; set; }
+
+    /// <summary>
+    /// Gets or sets the length of the returned content in bytes.
+    /// </summary>
+    public long? Compression { get; set; }
+
+    /// <summary>
+    /// Gets or sets the MIME type of the response.
+    /// </summary>
+    public string MimeType { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the response body text.
+    /// </summary>
+    public string? Text { get; set; }
+
+    /// <summary>
+    /// Gets or sets the encoding used for the response text.
+    /// </summary>
+    public string? Encoding { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents HAR cache information.
+/// </summary>
+public sealed class HarCache
+{
+    /// <summary>
+    /// Gets or sets the state of the cache entry before the request.
+    /// </summary>
+    public HarCacheEntry? BeforeRequest { get; set; }
+
+    /// <summary>
+    /// Gets or sets the state of the cache entry after the request.
+    /// </summary>
+    public HarCacheEntry? AfterRequest { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a HAR cache entry object.
+/// </summary>
+public sealed class HarCacheEntry
+{
+    /// <summary>
+    /// Gets or sets the expiration time of the cache entry.
+    /// </summary>
+    public string? Expires { get; set; }
+
+    /// <summary>
+    /// Gets or sets the last accessed time of the cache entry.
+    /// </summary>
+    public string LastAccess { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the ETag.
+    /// </summary>
+    public string ETag { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the number of times the entry has been opened.
+    /// </summary>
+    public int HitCount { get; set; }
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents HAR timing information.
+/// </summary>
+public sealed class HarTimings
+{
+    /// <summary>
+    /// Gets or sets the time spent in a queue waiting for a network connection.
+    /// </summary>
+    public double Blocked { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the DNS resolution time.
+    /// </summary>
+    public double Dns { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the time required to create a TCP connection.
+    /// </summary>
+    public double Connect { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the time required for SSL/TLS negotiation.
+    /// </summary>
+    public double Ssl { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the time required to send the HTTP request to the server.
+    /// </summary>
+    public double Send { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the waiting for a response from the server.
+    /// </summary>
+    public double Wait { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the time required to read the entire response from the server.
+    /// </summary>
+    public double Receive { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
diff --git a/dotnet/src/webdriver/BiDi/Network/Har/HarLog.cs b/dotnet/src/webdriver/BiDi/Network/Har/HarLog.cs
new file mode 100644
index 0000000000000..213e75daf48dd
--- /dev/null
+++ b/dotnet/src/webdriver/BiDi/Network/Har/HarLog.cs
@@ -0,0 +1,163 @@
+// <copyright file="HarLog.cs" company="Selenium Committers">
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+// </copyright>
+
+using System.Collections.Generic;
+
+namespace OpenQA.Selenium.BiDi.Network.Har;
+
+/// <summary>
+/// Represents the root object of exported HAR data.
+/// </summary>
+public sealed class HarFile
+{
+    /// <summary>
+    /// Gets or sets the log object.
+    /// </summary>
+    public HarLog Log { get; set; } = new HarLog();
+}
+
+/// <summary>
+/// Represents a HAR log object.
+/// </summary>
+public sealed class HarLog
+{
+    /// <summary>
+    /// Gets or sets the version of the HAR format.
+    /// </summary>
+    public string Version { get; set; } = "1.2";
+
+    /// <summary>
+    /// Gets or sets the creator information.
+    /// </summary>
+    public HarCreator Creator { get; set; } = new HarCreator();
+
+    /// <summary>
+    /// Gets or sets the browser information.
+    /// </summary>
+    public HarBrowser? Browser { get; set; }
+
+    /// <summary>
+    /// Gets or sets the list of page objects.
+    /// </summary>
+    public List<HarPage> Pages { get; set; } = new List<HarPage>();
+
+    /// <summary>
+    /// Gets or sets the list of entry objects.
+    /// </summary>
+    public List<HarEntry> Entries { get; set; } = new List<HarEntry>();
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents the creator information.
+/// </summary>
+public sealed class HarCreator
+{
+    /// <summary>
+    /// Gets or sets the name of the creator.
+    /// </summary>
+    public string Name { get; set; } = "Selenium";
+
+    /// <summary>
+    /// Gets or sets the version of the creator.
+    /// </summary>
+    public string Version { get; set; } = "4.0";
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents the browser information.
+/// </summary>
+public sealed class HarBrowser
+{
+    /// <summary>
+    /// Gets or sets the name of the browser.
+    /// </summary>
+    public string Name { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the version of the browser.
+    /// </summary>
+    public string Version { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents a page object.
+/// </summary>
+public sealed class HarPage
+{
+    /// <summary>
+    /// Gets or sets the unique identifier for the page.
+    /// </summary>
+    public string Id { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the page title.
+    /// </summary>
+    public string Title { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the date and time stamp for the page.
+    /// </summary>
+    public string StartedDateTime { get; set; } = string.Empty;
+
+    /// <summary>
+    /// Gets or sets the page timings.
+    /// </summary>
+    public HarPageTimings PageTimings { get; set; } = new HarPageTimings();
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
+
+/// <summary>
+/// Represents page timing information.
+/// </summary>
+public sealed class HarPageTimings
+{
+    /// <summary>
+    /// Gets or sets the time in milliseconds for the page to load.
+    /// </summary>
+    public double OnContentLoad { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets the time in milliseconds for the page to finish loading.
+    /// </summary>
+    public double OnLoad { get; set; } = -1;
+
+    /// <summary>
+    /// Gets or sets an optional comment.
+    /// </summary>
+    public string? Comment { get; set; }
+}
diff --git a/dotnet/src/webdriver/BiDi/Network/Har/HarRecorder.cs b/dotnet/src/webdriver/BiDi/Network/Har/HarRecorder.cs
new file mode 100644
index 0000000000000..34e62d7b3a392
--- /dev/null
+++ b/dotnet/src/webdriver/BiDi/Network/Har/HarRecorder.cs
@@ -0,0 +1,410 @@
+// <copyright file="HarRecorder.cs" company="Selenium Committers">
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+// </copyright>
+
+using System;
+using System.Collections.Generic;
+using System.IO;
+using System.Linq;
+using System.Text.Json;
+using System.Threading.Tasks;
+
+namespace OpenQA.Selenium.BiDi.Network.Har;
+
+/// <summary>
+/// Records network traffic and provides methods to save it as HAR format.
+/// </summary>
+public sealed class HarRecorder : IHarRecorder
+{
+    private readonly BiDi _bidi;
+    private readonly HarRecordingOptions _options;
+    private readonly HarFile _harFile;
+    private readonly Dictionary<string, HarEntry> _pendingRequests;
+    private readonly string _tempDirectoryPath;
+    private Subscription? _beforeRequestSubscription;
+    private Subscription? _responseStartedSubscription;
+    private Subscription? _responseCompletedSubscription;
+    private Collector? _dataCollector;
+
+    internal HarRecorder(BiDi bidi, HarRecordingOptions options)
+    {
+        _bidi = bidi ?? throw new ArgumentNullException(nameof(bidi));
+        _options = options ?? throw new ArgumentNullException(nameof(options));
+        _harFile = new HarFile();
+        _pendingRequests = new Dictionary<string, HarEntry>();
+        _tempDirectoryPath = Path.Combine(Path.GetTempPath(), $"selenium-har-{Guid.NewGuid()}");
+        Directory.CreateDirectory(_tempDirectoryPath);
+
+        if (!string.IsNullOrEmpty(options.BrowserName))
+        {
+            _harFile.Log.Browser = new HarBrowser
+            {
+                Name = options.BrowserName,
+                Version = options.BrowserVersion ?? string.Empty
+            };
+        }
+    }
+
+    internal async Task StartAsync()
+    {
+        // Always create data collector for capturing request and response bodies
+        _dataCollector = await _bidi.Network.AddDataCollectorAsync([DataType.Request, DataType.Response], 200000000).ConfigureAwait(false);
+
+        _beforeRequestSubscription = await _bidi.Network.OnBeforeRequestSentAsync(OnBeforeRequestSent).ConfigureAwait(false);
+        _responseStartedSubscription = await _bidi.Network.OnResponseStartedAsync(OnResponseStarted).ConfigureAwait(false);
+        _responseCompletedSubscription = await _bidi.Network.OnResponseCompletedAsync(OnResponseCompleted).ConfigureAwait(false);
+    }
+
+    private void OnBeforeRequestSent(BeforeRequestSentEventArgs args)
+    {
+        var entry = new HarEntry
+        {
+            StartedDateTime = args.Timestamp.ToString("o"),
+            Request = ConvertRequest(args.Request),
+            Timings = ConvertTimings(args.Request.Timings),
+            Time = 0
+        };
+
+        if (args.Context != null)
+        {
+            entry.Pageref = args.Context.Id;
+        }
+
+        lock (_pendingRequests)
+        {
+            _pendingRequests[args.Request.Request.Id] = entry;
+        }
+    }
+
+    private void OnResponseStarted(ResponseStartedEventArgs args)
+    {
+        lock (_pendingRequests)
+        {
+            if (_pendingRequests.TryGetValue(args.Request.Request.Id, out var entry))
+            {
+                entry.Response = ConvertResponse(args.Response);
+            }
+        }
+    }
+
+    private async void OnResponseCompleted(ResponseCompletedEventArgs args)
+    {
+        HarEntry? entry = null;
+        
+        lock (_pendingRequests)
+        {
+            if (_pendingRequests.TryGetValue(args.Request.Request.Id, out entry))
+            {
+                entry.Response = ConvertResponse(args.Response);
+                
+                // Calculate total time
+                var timings = args.Request.Timings;
+                entry.Time = CalculateTotalTime(timings);
+            }
+        }
+
+        if (entry != null)
+        {
+            // Retrieve request and response bodies
+            if (_dataCollector != null)
+            {
+                try
+                {
+                    // Get request body
+                    var requestBody = await _bidi.Network.GetDataAsync(DataType.Request, args.Request.Request).ConfigureAwait(false);
+                    if (requestBody != null)
+                    {
+                        entry.Request.PostData = new HarPostData
+                        {
+                            MimeType = GetContentType(entry.Request.Headers),
+                            Text = (string)requestBody
+                        };
+                    }
+                }
+                catch
+                {
+                    // Request body may not be available for all requests (e.g., GET requests)
+                }
+
+                try
+                {
+                    // Get response body
+                    var responseBody = await _bidi.Network.GetDataAsync(DataType.Response, args.Request.Request).ConfigureAwait(false);
+                    if (responseBody != null)
+                    {
+                        var bodyText = (string)responseBody;
+                        entry.Response.Content.Text = bodyText;
+                        entry.Response.Content.Size = System.Text.Encoding.UTF8.GetByteCount(bodyText);
+                    }
+                }
+                catch
+                {
+                    // Response body may not be available for all responses
+                }
+            }
+
+            // Flush entry to dedicated temp file (outside of lock for better concurrency)
+            FlushEntryToTempFile(entry, args.Request.Request.Id);
+            
+            lock (_pendingRequests)
+            {
+                _pendingRequests.Remove(args.Request.Request.Id);
+            }
+        }
+    }
+
+    private void FlushEntryToTempFile(HarEntry entry, string requestId)
+    {
+        // Use dedicated file per entry for better concurrency safety
+        var sanitizedId = string.Concat(requestId.Where(c => char.IsLetterOrDigit(c) || c == '-' || c == '_'));
+        var fileName = $"{sanitizedId}_{Guid.NewGuid()}.json";
+        var filePath = Path.Combine(_tempDirectoryPath, fileName);
+
+        var jsonOptions = new JsonSerializerOptions
+        {
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull
+        };
+
+        var entryJson = JsonSerializer.Serialize(entry, jsonOptions);
+        File.WriteAllText(filePath, entryJson);
+    }
+
+    private string GetContentType(List<HarHeader> headers)
+    {
+        var contentTypeHeader = headers.FirstOrDefault(h => h.Name.Equals("Content-Type", StringComparison.OrdinalIgnoreCase));
+        return contentTypeHeader?.Value ?? "application/octet-stream";
+    }
+
+    private HarRequest ConvertRequest(RequestData request)
+    {
+        var harRequest = new HarRequest
+        {
+            Method = request.Method,
+            Url = request.Url,
+            HttpVersion = "HTTP/1.1",
+            HeadersSize = request.HeadersSize ?? -1,
+            BodySize = request.BodySize ?? -1
+        };
+
+        foreach (var header in request.Headers)
+        {
+            harRequest.Headers.Add(new HarHeader
+            {
+                Name = header.Name,
+                Value = (string)header.Value
+            });
+        }
+
+        foreach (var cookie in request.Cookies)
+        {
+            harRequest.Cookies.Add(new HarCookie
+            {
+                Name = cookie.Name,
+                Value = (string)cookie.Value,
+                Domain = cookie.Domain,
+                Path = cookie.Path,
+                HttpOnly = cookie.HttpOnly,
+                Secure = cookie.Secure,
+                Expires = cookie.Expiry?.ToString("o")
+            });
+        }
+
+        // Parse query string from URL
+        var uri = new Uri(request.Url);
+        if (!string.IsNullOrEmpty(uri.Query))
+        {
+            var queryString = uri.Query.TrimStart('?');
+            var queryParams = queryString.Split('&');
+            foreach (var param in queryParams)
+            {
+                var parts = param.Split('=', 2);
+                harRequest.QueryString.Add(new HarQueryParam
+                {
+                    Name = Uri.UnescapeDataString(parts[0]),
+                    Value = parts.Length > 1 ? Uri.UnescapeDataString(parts[1]) : string.Empty
+                });
+            }
+        }
+
+        return harRequest;
+    }
+
+    private HarResponse ConvertResponse(ResponseData response)
+    {
+        var harResponse = new HarResponse
+        {
+            Status = response.Status,
+            StatusText = response.StatusText,
+            HttpVersion = response.Protocol,
+            HeadersSize = response.HeadersSize ?? -1,
+            BodySize = response.BodySize ?? -1,
+            Content = new HarContent
+            {
+                Size = response.BodySize ?? 0,
+                MimeType = response.MimeType
+            }
+        };
+
+        foreach (var header in response.Headers)
+        {
+            var headerValue = (string)header.Value;
+            harResponse.Headers.Add(new HarHeader
+            {
+                Name = header.Name,
+                Value = headerValue
+            });
+
+            // Check for redirect URL
+            if (header.Name.Equals("Location", StringComparison.OrdinalIgnoreCase))
+            {
+                harResponse.RedirectURL = headerValue;
+            }
+        }
+
+        return harResponse;
+    }
+
+    private HarTimings ConvertTimings(FetchTimingInfo timings)
+    {
+        return new HarTimings
+        {
+            Blocked = -1,
+            Dns = CalculateDuration(timings.DnsStart, timings.DnsEnd),
+            Connect = CalculateDuration(timings.ConnectStart, timings.ConnectEnd),
+            Ssl = CalculateDuration(timings.TlsStart, timings.ConnectEnd),
+            Send = CalculateDuration(timings.RequestStart, timings.RequestStart),
+            Wait = CalculateDuration(timings.RequestStart, timings.ResponseStart),
+            Receive = CalculateDuration(timings.ResponseStart, timings.ResponseEnd)
+        };
+    }
+
+    private double CalculateDuration(double start, double end)
+    {
+        if (start < 0 || end < 0 || end < start)
+        {
+            return -1;
+        }
+        return end - start;
+    }
+
+    private double CalculateTotalTime(FetchTimingInfo timings)
+    {
+        if (timings.FetchStart >= 0 && timings.ResponseEnd >= 0 && timings.ResponseEnd >= timings.FetchStart)
+        {
+            return timings.ResponseEnd - timings.FetchStart;
+        }
+        return 0;
+    }
+
+    private void LoadEntriesFromTempFiles()
+    {
+        _harFile.Log.Entries.Clear();
+
+        if (Directory.Exists(_tempDirectoryPath))
+        {
+            var jsonOptions = new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true
+            };
+
+            var files = Directory.GetFiles(_tempDirectoryPath, "*.json");
+            foreach (var file in files)
+            {
+                try
+                {
+                    var entryJson = File.ReadAllText(file);
+                    var entry = JsonSerializer.Deserialize<HarEntry>(entryJson, jsonOptions);
+                    if (entry != null)
+                    {
+                        _harFile.Log.Entries.Add(entry);
+                    }
+                }
+                catch
+                {
+                    // Skip corrupted or incomplete files
+                }
+            }
+        }
+    }
+
+    /// <summary>
+    /// Saves the captured network traffic to a HAR file.
+    /// </summary>
+    /// <param name="filePath">The path where the HAR file should be saved.</param>
+    /// <returns>A task that represents the asynchronous operation.</returns>
+    public async Task SaveAsync(string filePath)
+    {
+        if (string.IsNullOrEmpty(filePath))
+        {
+            throw new ArgumentException("File path cannot be null or empty.", nameof(filePath));
+        }
+
+        // Load entries from temp files before saving
+        LoadEntriesFromTempFiles();
+
+        var options = new JsonSerializerOptions
+        {
+            WriteIndented = true,
+            PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
+            DefaultIgnoreCondition = System.Text.Json.Serialization.JsonIgnoreCondition.WhenWritingNull
+        };
+
+        var json = JsonSerializer.Serialize(_harFile, options);
+        await File.WriteAllTextAsync(filePath, json).ConfigureAwait(false);
+    }
+
+    /// <summary>
+    /// Disposes the recorder and unsubscribes from network events.
+    /// </summary>
+    public async ValueTask DisposeAsync()
+    {
+        if (_beforeRequestSubscription != null)
+        {
+            await _beforeRequestSubscription.DisposeAsync().ConfigureAwait(false);
+        }
+
+        if (_responseStartedSubscription != null)
+        {
+            await _responseStartedSubscription.DisposeAsync().ConfigureAwait(false);
+        }
+
+        if (_responseCompletedSubscription != null)
+        {
+            await _responseCompletedSubscription.DisposeAsync().ConfigureAwait(false);
+        }
+
+        if (_dataCollector != null)
+        {
+            await _bidi.Network.RemoveDataCollectorAsync(_dataCollector).ConfigureAwait(false);
+        }
+
+        // Clean up temp directory
+        if (Directory.Exists(_tempDirectoryPath))
+        {
+            try
+            {
+                Directory.Delete(_tempDirectoryPath, recursive: true);
+            }
+            catch
+            {
+                // Ignore errors when deleting temp directory
+            }
+        }
+    }
+}
diff --git a/dotnet/src/webdriver/BiDi/Network/Har/README.md b/dotnet/src/webdriver/BiDi/Network/Har/README.md
new file mode 100644
index 0000000000000..8179a1b5c7d06
--- /dev/null
+++ b/dotnet/src/webdriver/BiDi/Network/Har/README.md
@@ -0,0 +1,73 @@
+# HAR Recording Extension for BiDi
+
+This extension provides the ability to record network traffic using the BiDi protocol and export it to HAR (HTTP Archive) format, including request and response body content.
+
+## Usage Example
+
+```csharp
+using OpenQA.Selenium;
+using OpenQA.Selenium.Chrome;
+using OpenQA.Selenium.BiDi;
+using OpenQA.Selenium.BiDi.Network.Har;
+
+// Create a WebDriver instance with BiDi enabled
+var options = new ChromeOptions();
+options.AddArgument("--remote-allow-origins=*");
+options.EnableBiDi();
+
+using var driver = new ChromeDriver(options);
+
+// Connect to BiDi
+await using var bidi = await driver.AsBiDiAsync();
+
+// Start recording network traffic (includes request/response bodies by default)
+await using var recorder = await bidi.RecordHarAsync(new HarRecordingOptions
+{
+    BrowserName = "Chrome",
+    BrowserVersion = "120.0"
+});
+
+// Navigate to a page
+driver.Navigate().GoToUrl("https://www.example.com");
+
+// Wait for some network activity
+await Task.Delay(2000);
+
+// Save the recorded traffic to a HAR file
+await recorder.SaveAsync("network-traffic.har");
+```
+
+## HAR Recording Options
+
+The `HarRecordingOptions` class allows you to configure the recording:
+
+- `BrowserName`: The browser name to include in the HAR metadata
+- `BrowserVersion`: The browser version to include in the HAR metadata
+
+## HAR File Format
+
+The generated HAR file follows the HAR 1.2 specification and includes:
+
+- Request details (method, URL, headers, cookies, query parameters)
+- Response details (status code, headers, content type)
+- Timing information (DNS, connect, SSL, send, wait, receive)
+- Request/response body content (automatically recorded)
+- Metadata (browser info, timestamps)
+
+## Body Content Recording
+
+By default, the HAR recorder records request and response bodies for all network traffic. A network data collector is automatically created when you start recording traffic. This provides complete visibility into all request and response payloads.
+
+**Memory Optimization:** To minimize memory usage, recorded network entries are written to a temporary file as they are completed. The entries are only loaded into memory when you call `SaveAsync()`. This allows for recording large amounts of network traffic without consuming excessive memory.
+
+**Note:** Recording request/response bodies may increase memory usage for large requests/responses.
+
+## Disposing the Recorder
+
+The `IHarRecorder` implements `IAsyncDisposable` and should be disposed properly to unsubscribe from network events and clean up the data collector:
+
+```csharp
+await using var recorder = await bidi.RecordHarAsync();
+// ... record network traffic ...
+// Dispose is called automatically when leaving the using block
+```
diff --git a/dotnet/test/common/BiDi/Network/HarRecordingTest.cs b/dotnet/test/common/BiDi/Network/HarRecordingTest.cs
new file mode 100644
index 0000000000000..9c0db50188be6
--- /dev/null
+++ b/dotnet/test/common/BiDi/Network/HarRecordingTest.cs
@@ -0,0 +1,190 @@
+// <copyright file="HarRecordingTest.cs" company="Selenium Committers">
+// Licensed to the Software Freedom Conservancy (SFC) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The SFC licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+// </copyright>
+
+using NUnit.Framework;
+using OpenQA.Selenium.BiDi.BrowsingContext;
+using OpenQA.Selenium.BiDi.Network.Har;
+using System;
+using System.IO;
+using System.Linq;
+using System.Text.Json;
+using System.Threading.Tasks;
+
+namespace OpenQA.Selenium.BiDi.Network;
+
+class HarRecordingTest : BiDiTestFixture
+{
+    [Test]
+    public async Task CanRecordNetworkTrafficToHar()
+    {
+        var tempFile = Path.Combine(Path.GetTempPath(), $"selenium-har-{Guid.NewGuid()}.har");
+
+        try
+        {
+            await using var recorder = await bidi.RecordHarAsync(new HarRecordingOptions
+            {
+                BrowserName = "TestBrowser",
+                BrowserVersion = "1.0"
+            });
+
+            await context.NavigateAsync(UrlBuilder.WhereIs("bidi/logEntryAdded.html"), new() { Wait = ReadinessState.Complete });
+
+            await recorder.SaveAsync(tempFile);
+
+            Assert.That(File.Exists(tempFile), Is.True);
+
+            var jsonContent = await File.ReadAllTextAsync(tempFile);
+            Assert.That(jsonContent, Is.Not.Empty);
+
+            var harFile = JsonSerializer.Deserialize<HarFile>(jsonContent, new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true
+            });
+
+            Assert.That(harFile, Is.Not.Null);
+            Assert.That(harFile.Log, Is.Not.Null);
+            Assert.That(harFile.Log.Version, Is.EqualTo("1.2"));
+            Assert.That(harFile.Log.Creator.Name, Is.EqualTo("Selenium"));
+            Assert.That(harFile.Log.Browser, Is.Not.Null);
+            Assert.That(harFile.Log.Browser.Name, Is.EqualTo("TestBrowser"));
+            Assert.That(harFile.Log.Browser.Version, Is.EqualTo("1.0"));
+            Assert.That(harFile.Log.Entries, Is.Not.Empty);
+
+            var entry = harFile.Log.Entries.FirstOrDefault(e => e.Request.Url.Contains("logEntryAdded.html"));
+            Assert.That(entry, Is.Not.Null);
+            Assert.That(entry.Request.Method, Is.EqualTo("GET"));
+            Assert.That(entry.Response.Status, Is.EqualTo(200));
+        }
+        finally
+        {
+            if (File.Exists(tempFile))
+            {
+                File.Delete(tempFile);
+            }
+        }
+    }
+
+    [Test]
+    public async Task CanSaveHarToFile()
+    {
+        var tempFile = Path.Combine(Path.GetTempPath(), $"selenium-har-{Guid.NewGuid()}.har");
+
+        try
+        {
+            await using var recorder = await bidi.RecordHarAsync();
+
+            await context.NavigateAsync(UrlBuilder.WhereIs("bidi/logEntryAdded.html"), new() { Wait = ReadinessState.Complete });
+
+            await recorder.SaveAsync(tempFile);
+
+            Assert.That(File.Exists(tempFile), Is.True);
+
+            var jsonContent = await File.ReadAllTextAsync(tempFile);
+            Assert.That(jsonContent, Is.Not.Empty);
+
+            var harFile = JsonSerializer.Deserialize<HarFile>(jsonContent, new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true
+            });
+
+            Assert.That(harFile, Is.Not.Null);
+            Assert.That(harFile.Log, Is.Not.Null);
+            Assert.That(harFile.Log.Entries, Is.Not.Empty);
+        }
+        finally
+        {
+            if (File.Exists(tempFile))
+            {
+                File.Delete(tempFile);
+            }
+        }
+    }
+
+    [Test]
+    public async Task HarEntriesContainRequestDetails()
+    {
+        var tempFile = Path.Combine(Path.GetTempPath(), $"selenium-har-{Guid.NewGuid()}.har");
+
+        try
+        {
+            await using var recorder = await bidi.RecordHarAsync();
+
+            await context.NavigateAsync(UrlBuilder.WhereIs("bidi/logEntryAdded.html"), new() { Wait = ReadinessState.Complete });
+
+            await recorder.SaveAsync(tempFile);
+
+            var jsonContent = await File.ReadAllTextAsync(tempFile);
+            var harFile = JsonSerializer.Deserialize<HarFile>(jsonContent, new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true
+            });
+
+            var entry = harFile.Log.Entries.FirstOrDefault(e => e.Request.Url.Contains("logEntryAdded.html"));
+
+            Assert.That(entry, Is.Not.Null);
+            Assert.That(entry.StartedDateTime, Is.Not.Empty);
+            Assert.That(entry.Time, Is.GreaterThanOrEqualTo(0));
+            Assert.That(entry.Request.Headers, Is.Not.Empty);
+            Assert.That(entry.Response.Headers, Is.Not.Empty);
+            Assert.That(entry.Timings, Is.Not.Null);
+        }
+        finally
+        {
+            if (File.Exists(tempFile))
+            {
+                File.Delete(tempFile);
+            }
+        }
+    }
+
+    [Test]
+    public async Task CanRecordRequestAndResponseBodies()
+    {
+        var tempFile = Path.Combine(Path.GetTempPath(), $"selenium-har-{Guid.NewGuid()}.har");
+
+        try
+        {
+            await using var recorder = await bidi.RecordHarAsync();
+
+            await context.NavigateAsync(UrlBuilder.WhereIs("bidi/logEntryAdded.html"), new() { Wait = ReadinessState.Complete });
+
+            await recorder.SaveAsync(tempFile);
+
+            var jsonContent = await File.ReadAllTextAsync(tempFile);
+            var harFile = JsonSerializer.Deserialize<HarFile>(jsonContent, new JsonSerializerOptions
+            {
+                PropertyNameCaseInsensitive = true
+            });
+
+            var entry = harFile.Log.Entries.FirstOrDefault(e => e.Request.Url.Contains("logEntryAdded.html"));
+
+            Assert.That(entry, Is.Not.Null);
+            Assert.That(entry.Response.Content.Text, Is.Not.Null);
+            Assert.That(entry.Response.Content.Text, Is.Not.Empty);
+            Assert.That(entry.Response.Content.Size, Is.GreaterThan(0));
+        }
+        finally
+        {
+            if (File.Exists(tempFile))
+            {
+                File.Delete(tempFile);
+            }
+        }
+    }
+}