diff --git a/CHANGELOG.md b/CHANGELOG.md
index fd4efc51c1..f2f847fa4a 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -22,6 +22,7 @@ the release.
   ([#2644](https://github.com/open-telemetry/opentelemetry-demo/pull/2644))
 * [frontend] fix item calculation and shipping
   ([#2684](https://github.com/open-telemetry/opentelemetry-demo/pull/2684))
+* [flagd-ui] add back legacy REST APIs to empower programmatic usage ([#2720](https://github.com/open-telemetry/opentelemetry-demo/pull/2720))
 
 ## 2.1.3
 
diff --git a/src/flagd-ui/lib/flagd_ui_web/controllers/feature_controller.ex b/src/flagd-ui/lib/flagd_ui_web/controllers/feature_controller.ex
index 551f225c2f..906971aef9 100644
--- a/src/flagd-ui/lib/flagd_ui_web/controllers/feature_controller.ex
+++ b/src/flagd-ui/lib/flagd_ui_web/controllers/feature_controller.ex
@@ -9,4 +9,11 @@ defmodule FlagdUiWeb.FeatureController do
 
     json(conn, %{"flags" => flags})
   end
+
+  def write(conn, %{"data" => data}) do
+    payload = Jason.encode!(data)
+    GenServer.cast(Storage, {:replace, payload})
+
+    json(conn, %{})
+  end
 end
diff --git a/src/flagd-ui/lib/flagd_ui_web/router.ex b/src/flagd-ui/lib/flagd_ui_web/router.ex
index df7d8bae18..b32e66136d 100644
--- a/src/flagd-ui/lib/flagd_ui_web/router.ex
+++ b/src/flagd-ui/lib/flagd_ui_web/router.ex
@@ -29,6 +29,9 @@ defmodule FlagdUiWeb.Router do
     pipe_through :api
 
     get "/read", FeatureController, :read
+    get "/read-file", FeatureController, :read
+    post "/write", FeatureController, :write
+    post "/write-to-file", FeatureController, :write
   end
 
   # Enable LiveDashboard and Swoosh mailbox preview in development
diff --git a/src/flagd-ui/mix.exs b/src/flagd-ui/mix.exs
index 7fa0130066..a8fb490851 100644
--- a/src/flagd-ui/mix.exs
+++ b/src/flagd-ui/mix.exs
@@ -7,7 +7,7 @@ defmodule FlagdUi.MixProject do
   def project do
     [
       app: :flagd_ui,
-      version: "0.1.0",
+      version: "0.1.1",
       elixir: "~> 1.15",
       elixirc_paths: elixirc_paths(Mix.env()),
       start_permanent: Mix.env() == :prod,
diff --git a/src/flagd-ui/test/flagd_ui_web/controllers/feature_controller_test.exs b/src/flagd-ui/test/flagd_ui_web/controllers/feature_controller_test.exs
new file mode 100644
index 0000000000..8d24cc3d81
--- /dev/null
+++ b/src/flagd-ui/test/flagd_ui_web/controllers/feature_controller_test.exs
@@ -0,0 +1,136 @@
+# Copyright The OpenTelemetry Authors
+# SPDX-License-Identifier: Apache-2.0
+
+defmodule FlagdUiWeb.FeatureControllerTest do
+  use FlagdUiWeb.ConnCase
+
+  setup do
+    file_content = GenServer.call(Storage, :read)
+
+    on_exit(fn ->
+      GenServer.cast(Storage, {:replace, Jason.encode!(file_content)})
+    end)
+  end
+
+  test "GET /api/read", %{conn: conn} do
+    conn = get(conn, ~p"/api/read")
+
+    assert %{
+             "flags" => %{
+               "adFailure" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Fail ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => false, "on" => true}
+               },
+               "adHighCpu" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Triggers high cpu load in the ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => false, "on" => true}
+               }
+             }
+           } = json_response(conn, 200)
+  end
+
+  test "GET /api/read-file (legacy API)", %{conn: conn} do
+    conn = get(conn, ~p"/api/read-file")
+
+    assert %{
+             "flags" => %{
+               "adFailure" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Fail ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => false, "on" => true}
+               },
+               "adHighCpu" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Triggers high cpu load in the ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => false, "on" => true}
+               }
+             }
+           } = json_response(conn, 200)
+  end
+
+  test "POST /api/write", %{conn: conn} do
+    data = %{
+      "flags" => %{
+        "adFailure" => %{
+          "defaultVariant" => "off",
+          "description" => "Fail ad service",
+          "state" => "ENABLED",
+          "variants" => %{"off" => true, "on" => false}
+        },
+        "adHighCpu" => %{
+          "defaultVariant" => "off",
+          "description" => "Triggers high cpu load in the ad service",
+          "state" => "ENABLED",
+          "variants" => %{"off" => true, "on" => false}
+        }
+      }
+    }
+
+    conn = post(conn, ~p"/api/write", %{"data" => data})
+
+    conn = get(conn, ~p"/api/read")
+
+    assert %{
+             "flags" => %{
+               "adFailure" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Fail ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => true, "on" => false}
+               },
+               "adHighCpu" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Triggers high cpu load in the ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => true, "on" => false}
+               }
+             }
+           } = json_response(conn, 200)
+  end
+
+  test "POST /api/write-to-file (legacy API)", %{conn: conn} do
+    data = %{
+      "flags" => %{
+        "adFailure" => %{
+          "defaultVariant" => "off",
+          "description" => "Fail ad service",
+          "state" => "ENABLED",
+          "variants" => %{"off" => true, "on" => false}
+        },
+        "adHighCpu" => %{
+          "defaultVariant" => "off",
+          "description" => "Triggers high cpu load in the ad service",
+          "state" => "ENABLED",
+          "variants" => %{"off" => true, "on" => false}
+        }
+      }
+    }
+
+    conn = post(conn, ~p"/api/write-to-file", %{"data" => data})
+
+    conn = get(conn, ~p"/api/read-file")
+
+    assert %{
+             "flags" => %{
+               "adFailure" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Fail ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => true, "on" => false}
+               },
+               "adHighCpu" => %{
+                 "defaultVariant" => "off",
+                 "description" => "Triggers high cpu load in the ad service",
+                 "state" => "ENABLED",
+                 "variants" => %{"off" => true, "on" => false}
+               }
+             }
+           } = json_response(conn, 200)
+  end
+end