diff --git a/Cargo.toml b/Cargo.toml
index d7056c6..c9e696c 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -23,6 +23,7 @@ uuid = { version = "1.13.2", features = ["serde", "v7"] }
 [dev-dependencies]
 dotenv = "0.15.0"
 ctor = "0.1.26"
+tokio = { version = "1.47.1", features = ["rt", "macros"] }
 
 [features]
 default = ["async-client"]
diff --git a/README.md b/README.md
index 3fd7966..d8189d9 100644
--- a/README.md
+++ b/README.md
@@ -22,3 +22,21 @@ event.insert_prop("key2", vec!["a", "b"]).unwrap();
 
 client.capture(event).unwrap();
 ```
+
+## Disabled Client
+
+The client can be initialized without an API key, which creates a disabled client. This is useful for development environments or when you need to conditionally disable event tracking (e.g., based on user privacy settings).
+
+```rust
+// Create a disabled client (no API key).
+let client = posthog_rs::client(posthog_rs::ClientOptions::default());
+
+// Events can be captured but won't be sent to PostHog.
+let event = posthog_rs::Event::new("test", "1234");
+client.capture(event).unwrap(); // Returns Ok(()) without sending anything.
+
+// Check if client is disabled.
+if client.is_disabled() {
+  println!("Client is disabled - events will not be sent");
+}
+```
diff --git a/src/client/async_client.rs b/src/client/async_client.rs
index 56139fb..c1ee404 100644
--- a/src/client/async_client.rs
+++ b/src/client/async_client.rs
@@ -23,9 +23,20 @@ pub async fn client<C: Into<ClientOptions>>(options: C) -> Client {
 }
 
 impl Client {
+    /// Returns true if this client is disabled (has no API key).
+    pub fn is_disabled(&self) -> bool {
+        self.options.api_key.is_none()
+    }
+
     /// Capture the provided event, sending it to PostHog.
+    /// If the client is disabled (no API key), this method returns Ok(()) without sending anything.
     pub async fn capture(&self, event: Event) -> Result<(), Error> {
-        let inner_event = InnerEvent::new(event, self.options.api_key.clone());
+        if self.is_disabled() {
+            return Ok(());
+        }
+
+        let api_key = self.options.api_key.as_ref().unwrap();
+        let inner_event = InnerEvent::new(event, api_key.clone());
 
         let payload =
             serde_json::to_string(&inner_event).map_err(|e| Error::Serialization(e.to_string()))?;
@@ -43,10 +54,16 @@ impl Client {
 
     /// Capture a collection of events with a single request. This function may be
     /// more performant than capturing a list of events individually.
+    /// If the client is disabled (no API key), this method returns Ok(()) without sending anything.
     pub async fn capture_batch(&self, events: Vec<Event>) -> Result<(), Error> {
+        if self.is_disabled() {
+            return Ok(());
+        }
+
+        let api_key = self.options.api_key.as_ref().unwrap();
         let events: Vec<_> = events
             .into_iter()
-            .map(|event| InnerEvent::new(event, self.options.api_key.clone()))
+            .map(|event| InnerEvent::new(event, api_key.clone()))
             .collect();
 
         let payload =
@@ -63,3 +80,53 @@ impl Client {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{ClientOptionsBuilder, Event};
+
+    #[tokio::test]
+    async fn test_client_without_api_key_is_disabled() {
+        let options = ClientOptions::default();
+
+        let client = client(options).await;
+
+        assert!(client.is_disabled());
+    }
+
+    #[tokio::test]
+    async fn test_client_with_api_key_is_enabled() {
+        let options = ClientOptionsBuilder::default()
+            .api_key(Some("test_key".to_string()))
+            .build()
+            .unwrap();
+
+        let client = client(options).await;
+
+        assert!(!client.is_disabled());
+    }
+
+    #[tokio::test]
+    async fn test_disabled_client_capture_returns_ok() {
+        let client = client(ClientOptions::default()).await;
+        let event = Event::new("test_event", "user_123");
+
+        let result = client.capture(event).await;
+
+        assert!(result.is_ok());
+    }
+
+    #[tokio::test]
+    async fn test_disabled_client_capture_batch_returns_ok() {
+        let client = client(ClientOptions::default()).await;
+        let events = vec![
+            Event::new("test_event1", "user_123"),
+            Event::new("test_event2", "user_456"),
+        ];
+
+        let result = client.capture_batch(events).await;
+
+        assert!(result.is_ok());
+    }
+}
diff --git a/src/client/blocking.rs b/src/client/blocking.rs
index 0f9af91..4740c48 100644
--- a/src/client/blocking.rs
+++ b/src/client/blocking.rs
@@ -23,9 +23,20 @@ pub fn client<C: Into<ClientOptions>>(options: C) -> Client {
 }
 
 impl Client {
+    /// Returns true if this client is disabled (has no API key).
+    pub fn is_disabled(&self) -> bool {
+        self.options.api_key.is_none()
+    }
+
     /// Capture the provided event, sending it to PostHog.
+    /// If the client is disabled (no API key), this method returns Ok(()) without sending anything.
     pub fn capture(&self, event: Event) -> Result<(), Error> {
-        let inner_event = InnerEvent::new(event, self.options.api_key.clone());
+        if self.is_disabled() {
+            return Ok(());
+        }
+
+        let api_key = self.options.api_key.as_ref().unwrap();
+        let inner_event = InnerEvent::new(event, api_key.clone());
 
         let payload =
             serde_json::to_string(&inner_event).map_err(|e| Error::Serialization(e.to_string()))?;
@@ -42,10 +53,16 @@ impl Client {
 
     /// Capture a collection of events with a single request. This function may be
     /// more performant than capturing a list of events individually.
+    /// If the client is disabled (no API key), this method returns Ok(()) without sending anything.
     pub fn capture_batch(&self, events: Vec<Event>) -> Result<(), Error> {
+        if self.is_disabled() {
+            return Ok(());
+        }
+
+        let api_key = self.options.api_key.as_ref().unwrap();
         let events: Vec<_> = events
             .into_iter()
-            .map(|event| InnerEvent::new(event, self.options.api_key.clone()))
+            .map(|event| InnerEvent::new(event, api_key.clone()))
             .collect();
 
         let payload =
@@ -61,3 +78,53 @@ impl Client {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::{ClientOptionsBuilder, Event};
+
+    #[test]
+    fn test_client_without_api_key_is_disabled() {
+        let options = ClientOptions::default();
+
+        let client = client(options);
+
+        assert!(client.is_disabled());
+    }
+
+    #[test]
+    fn test_client_with_api_key_is_enabled() {
+        let options = ClientOptionsBuilder::default()
+            .api_key(Some("test_key".to_string()))
+            .build()
+            .unwrap();
+
+        let client = client(options);
+
+        assert!(!client.is_disabled());
+    }
+
+    #[test]
+    fn test_disabled_client_capture_returns_ok() {
+        let client = client(ClientOptions::default());
+        let event = Event::new("test_event", "user_123");
+
+        let result = client.capture(event);
+
+        assert!(result.is_ok());
+    }
+
+    #[test]
+    fn test_disabled_client_capture_batch_returns_ok() {
+        let client = client(ClientOptions::default());
+        let events = vec![
+            Event::new("test_event1", "user_123"),
+            Event::new("test_event2", "user_456"),
+        ];
+
+        let result = client.capture_batch(events);
+
+        assert!(result.is_ok());
+    }
+}
diff --git a/src/client/mod.rs b/src/client/mod.rs
index a60d772..dd8aabd 100644
--- a/src/client/mod.rs
+++ b/src/client/mod.rs
@@ -19,16 +19,25 @@ pub use async_client::Client;
 pub struct ClientOptions {
     #[builder(default = "API_ENDPOINT.to_string()")]
     api_endpoint: String,
-    api_key: String,
+    #[builder(default = "None")]
+    api_key: Option<String>,
 
     #[builder(default = "30")]
     request_timeout_seconds: u64,
 }
 
+impl Default for ClientOptions {
+    fn default() -> Self {
+        ClientOptionsBuilder::default()
+            .build()
+            .expect("Default ClientOptions should always build successfully")
+    }
+}
+
 impl From<&str> for ClientOptions {
     fn from(api_key: &str) -> Self {
         ClientOptionsBuilder::default()
-            .api_key(api_key.to_string())
+            .api_key(Some(api_key.to_string()))
             .build()
             .expect("We always set the API key, so this is infallible")
     }