diff --git a/api/Navigator.json b/api/Navigator.json
index 2846dcda25e303..8ebf5e1b5ee5f4 100644
--- a/api/Navigator.json
+++ b/api/Navigator.json
@@ -324,6 +324,42 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "applies_UA_reduction": {
+          "__compat": {
+            "description": "Applies [User-agent reduction](https://developer.mozilla.org/docs/Web/HTTP/Guides/User-agent_reduction).",
+            "spec_url": "https://compat.spec.whatwg.org/#ua-string-section",
+            "support": {
+              "chrome": {
+                "version_added": "110"
+              },
+              "chrome_android": {
+                "version_added": "113"
+              },
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": {
+                "version_added": false
+              },
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
         }
       },
       "audioSession": {
@@ -2970,6 +3006,42 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "applies_UA_reduction": {
+          "__compat": {
+            "description": "Applies [User-agent reduction](https://developer.mozilla.org/docs/Web/HTTP/Guides/User-agent_reduction).",
+            "spec_url": "https://compat.spec.whatwg.org/#ua-string-section",
+            "support": {
+              "chrome": {
+                "version_added": "110"
+              },
+              "chrome_android": {
+                "version_added": "113"
+              },
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": {
+                "version_added": false
+              },
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
         }
       },
       "plugins": {
@@ -5487,6 +5559,42 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "applies_UA_reduction": {
+          "__compat": {
+            "description": "Applies [User-agent reduction](https://developer.mozilla.org/docs/Web/HTTP/Guides/User-agent_reduction).",
+            "spec_url": "https://compat.spec.whatwg.org/#ua-string-section",
+            "support": {
+              "chrome": {
+                "version_added": "110"
+              },
+              "chrome_android": {
+                "version_added": "113"
+              },
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": {
+                "version_added": false
+              },
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
         }
       },
       "userAgentData": {
diff --git a/http/headers/User-Agent.json b/http/headers/User-Agent.json
index d24f827d9f192a..36fd795a5d6d93 100644
--- a/http/headers/User-Agent.json
+++ b/http/headers/User-Agent.json
@@ -39,6 +39,42 @@
             "standard_track": true,
             "deprecated": false
           }
+        },
+        "applies_UA_reduction": {
+          "__compat": {
+            "description": "Applies [User-agent reduction](https://developer.mozilla.org/docs/Web/HTTP/Guides/User-agent_reduction).",
+            "spec_url": "https://compat.spec.whatwg.org/#ua-string-section",
+            "support": {
+              "chrome": {
+                "version_added": "110"
+              },
+              "chrome_android": {
+                "version_added": "113"
+              },
+              "edge": "mirror",
+              "firefox": {
+                "version_added": false
+              },
+              "firefox_android": "mirror",
+              "oculus": "mirror",
+              "opera": "mirror",
+              "opera_android": "mirror",
+              "safari": {
+                "version_added": false
+              },
+              "safari_ios": "mirror",
+              "samsunginternet_android": "mirror",
+              "webview_android": {
+                "version_added": false
+              },
+              "webview_ios": "mirror"
+            },
+            "status": {
+              "experimental": true,
+              "standard_track": true,
+              "deprecated": false
+            }
+          }
         }
       }
     }