diff --git a/packages/actor-core-cli/src/utils/rivet-api.ts b/packages/actor-core-cli/src/utils/rivet-api.ts
index 76e8a3e2f..eeed91d2d 100644
--- a/packages/actor-core-cli/src/utils/rivet-api.ts
+++ b/packages/actor-core-cli/src/utils/rivet-api.ts
@@ -1,4 +1,5 @@
 import { z, type ZodTypeAny } from "zod";
+import { httpUserAgent } from "actor-core/utils";
 
 export async function getServiceToken(
 	api: ReturnType<typeof createRivetApi>,
@@ -75,6 +76,7 @@ export function createRivetApi(endpoint: string, accessToken: string) {
 			headers: {
 				...opts.headers,
 				"Content-Type": "application/json",
+				"User-Agent": httpUserAgent(),
 				Authorization: `Bearer ${accessToken}`,
 			},
 		});
diff --git a/packages/actor-core/src/client/actor-conn.ts b/packages/actor-core/src/client/actor-conn.ts
index 3aea77237..f089dede8 100644
--- a/packages/actor-core/src/client/actor-conn.ts
+++ b/packages/actor-core/src/client/actor-conn.ts
@@ -5,6 +5,7 @@ import type * as wsToServer from "@/actor/protocol/message/to-server";
 import type { Encoding } from "@/actor/protocol/serde";
 import { importEventSource } from "@/common/eventsource";
 import { MAX_CONN_PARAMS_SIZE } from "@/common/network";
+import { httpUserAgent } from "@/utils";
 import { assertUnreachable, stringifyError } from "@/common/utils";
 import { importWebSocket } from "@/common/websocket";
 import type { ActorQuery } from "@/manager/protocol/query";
@@ -686,6 +687,9 @@ enc
 			const messageSerialized = this.#serialize(message);
 			const res = await fetch(url, {
 				method: "POST",
+				headers: {
+					"User-Agent": httpUserAgent(),
+				},
 				body: messageSerialized,
 			});
 
@@ -845,4 +849,4 @@ enc
  */
 
 export type ActorConn<AD extends AnyActorDefinition> = ActorConnRaw &
-	ActorDefinitionRpcs<AD>;
\ No newline at end of file
+	ActorDefinitionRpcs<AD>;
diff --git a/packages/actor-core/src/client/utils.ts b/packages/actor-core/src/client/utils.ts
index 38961781a..ca3b660a3 100644
--- a/packages/actor-core/src/client/utils.ts
+++ b/packages/actor-core/src/client/utils.ts
@@ -1,5 +1,6 @@
 import { deserialize } from "@/actor/protocol/serde";
 import { assertUnreachable, stringifyError } from "@/common/utils";
+import { httpUserAgent } from "@/utils";
 import { Encoding } from "@/mod";
 import * as cbor from "cbor-x";
 import { ActorError, HttpRequestError } from "./errors";
@@ -62,11 +63,14 @@ export async function sendHttpRequest<
 		// Make the HTTP request
 		response = await fetch(opts.url, {
 			method: opts.method,
-			headers: contentType
-				? {
-						"Content-Type": contentType,
-					}
-				: {},
+			headers: {
+				"User-Agent": httpUserAgent(),
+				...(contentType
+					? {
+							"Content-Type": contentType,
+						}
+					: {}),
+			},
 			body: bodyData,
 		});
 	} catch (error) {
diff --git a/packages/actor-core/src/utils.ts b/packages/actor-core/src/utils.ts
index 9bd5bb45d..16dee2629 100644
--- a/packages/actor-core/src/utils.ts
+++ b/packages/actor-core/src/utils.ts
@@ -1 +1,24 @@
 export { assertUnreachable } from "./common/utils";
+import pkgJson from "../package.json" with { type: "json" };
+
+export const VERSION = pkgJson.version;
+
+let _userAgent: string | undefined = undefined;
+
+export function httpUserAgent(): string {
+	// Return cached value if already initialized
+	if (_userAgent !== undefined) {
+		return _userAgent;
+	}
+
+	// Library
+	let userAgent = `ActorCore/${VERSION}`;
+
+	// Navigator
+	const navigatorObj = typeof navigator !== "undefined" ? navigator : undefined;
+	if (navigatorObj?.userAgent) userAgent += ` ${navigatorObj.userAgent}`;
+
+	_userAgent = userAgent;
+
+	return userAgent;
+}
diff --git a/packages/platforms/rivet/src/rivet-client.ts b/packages/platforms/rivet/src/rivet-client.ts
index 188a9f5bb..073ee2870 100644
--- a/packages/platforms/rivet/src/rivet-client.ts
+++ b/packages/platforms/rivet/src/rivet-client.ts
@@ -1,3 +1,5 @@
+import { httpUserAgent } from "actor-core/utils";
+
 export interface RivetClientConfig {
 	endpoint: string;
 	token: string;
@@ -23,6 +25,7 @@ export async function rivetRequest<RequestBody, ResponseBody>(
 		method,
 		headers: {
 			"Content-Type": "application/json",
+			"User-Agent": httpUserAgent(),
 			Authorization: `Bearer ${config.token}`,
 		},
 		body: body ? JSON.stringify(body) : undefined,