RivetKit React Client

Use this skill when building React apps that connect to Rivet Actors with @rivetkit/react.

First Steps

1. Install the React client (latest: 2.3.0-rc.5)

   npm install @rivetkit/react@2.3.0-rc.5
   

2. Create hooks with createRivetKit() and connect with useActor().

Error Handling Policy

• Prefer fail-fast behavior by default.
• Avoid try/catch unless absolutely needed.
• If a catch is used, handle the error explicitly, at minimum by logging it.

Getting Started

See the React quickstart guide for getting started.

Install

Minimal Client

import { createRivetKit } from "@rivetkit/react";
import type { registry } from "./index";

const { useActor } = createRivetKit<typeof registry>({
  endpoint: "https://my-namespace:pk_...@api.rivet.dev",
});

function Counter() {
  const { connection, connStatus } = useActor({ name: "counter", key: ["my-counter"] });

  if (connStatus !== "connected" || !connection) return <div>Connecting...</div>;
  return <button onClick={() => connection.increment(1)}>+</button>;
}

import { actor, setup } from "rivetkit";

export const counter = actor({
  state: { count: 0 },
  actions: {
    increment: (c, x: number) => {
      c.state.count += x;
      c.broadcast("newCount", c.state.count);
      return c.state.count;
    },
  },
});

export const registry = setup({
  use: { counter },
});

registry.start();

Stateless vs Stateful

import { createRivetKit } from "@rivetkit/react";

const { useActor } = createRivetKit();

function Counter() {
  const counter = useActor({ name: "counter", key: ["my-counter"] });

  const increment = async () => {
    await counter.connection?.increment(1);
  };

  return <button onClick={increment}>+</button>;
}

// Stateless: use createClient for one-off calls (SSR or utilities)
import { createClient } from "rivetkit/client";

const client = createClient();
await client.counter.getOrCreate(["my-counter"]).increment(1);

Getting Actors

import { createRivetKit } from "@rivetkit/react";
import { createClient } from "rivetkit/client";

const { useActor } = createRivetKit();

function ChatRoom() {
  const room = useActor({ name: "chatRoom", key: ["room-42"] });
  return <div>{room.connStatus}</div>;
}

// For get/getOrCreate/create/getForId, use createClient
const client = createClient();
const handle = client.chatRoom.getOrCreate(["room-42"]);
const existing = client.chatRoom.get(["room-42"]);
const created = await client.game.create(["game-1"], { input: { mode: "ranked" } });
const byId = client.chatRoom.getForId("actor-id");
const resolvedId = await handle.resolve();

Connection Parameters

import { createRivetKit } from "@rivetkit/react";

const { useActor } = createRivetKit();

function Chat() {
  const chat = useActor({
    name: "chatRoom",
    key: ["general"],
    params: { authToken: "jwt-token-here" },
  });

  return <div>{chat.connStatus}</div>;
}

Subscribing to Events

import { createRivetKit } from "@rivetkit/react";

const { useActor } = createRivetKit();

function Chat() {
  const chat = useActor({ name: "chatRoom", key: ["general"] });

  chat.useEvent("message", (msg) => {
    console.log("message:", msg);
  });

  return null;
}

Connection Lifecycle

import { createRivetKit } from "@rivetkit/react";

const { useActor } = createRivetKit();

function CounterStatus() {
  const actor = useActor({ name: "counter", key: ["my-counter"] });

  if (actor.connStatus === "connected") {
    console.log("connected");
  }

  if (actor.error) {
    console.error(actor.error);
  }

  return null;
}

Low-Level HTTP & WebSocket

Use the JavaScript client for raw HTTP and WebSocket access:

import { createClient } from "rivetkit/client";

const client = createClient();
const handle = client.chatRoom.getOrCreate(["general"]);

const response = await handle.fetch("history");
const history = await response.json();

const ws = await handle.webSocket("stream");
ws.addEventListener("message", (event) => {
  console.log("message:", event.data);
});
ws.send("hello");

Calling from Backend

Use the JavaScript client on your backend (Node.js/Bun). See the JavaScript client docs.

Error Handling

import { ActorError } from "rivetkit/client";
import { createRivetKit } from "@rivetkit/react";

const { useActor } = createRivetKit();

function Profile() {
  const actor = useActor({ name: "user", key: ["user-123"] });

  const updateUsername = async () => {
    try {
      await actor.connection?.updateUsername("ab");
    } catch (error) {
      if (error instanceof ActorError) {
        console.log(error.code, error.metadata);
      }
    }
  };

  return <button onClick={updateUsername}>Update</button>;
}

Concepts

Keys

Keys uniquely identify actor instances. Use compound keys (arrays) for hierarchical addressing:

import { createRivetKit } from "@rivetkit/react";
import type { registry } from "./index";

const { useActor } = createRivetKit<typeof registry>("http://localhost:6420");

function ChatRoom() {
  const room = useActor({ name: "chatRoom", key: ["org-acme", "general"] });
  return <div>{room.connStatus}</div>;
}

import { actor, setup } from "rivetkit";

export const chatRoom = actor({
  state: { messages: [] as string[] },
  actions: {
    getRoomInfo: (c) => ({ org: c.key[0], room: c.key[1] }),
  },
});

export const registry = setup({
  use: { chatRoom },
});

registry.start();

Don't build keys with string interpolation like "org:${userId}" when userId contains user data. Use arrays instead to prevent key injection attacks.

Environment Variables

createRivetKit() (and the underlying createClient() instance) automatically read:

• RIVET_ENDPOINT
• RIVET_NAMESPACE
• RIVET_TOKEN
• RIVET_RUNNER

Defaults to http://localhost:6420 when unset. RivetKit runs on port 6420 by default.

Endpoint Format

Endpoints support URL auth syntax:

https://namespace:token@api.rivet.dev

You can also pass the endpoint without auth and provide RIVET_NAMESPACE and RIVET_TOKEN separately. For serverless deployments, use your app's /api/rivet URL. See Endpoints for details.

API Reference

Package: @rivetkit/react

• createRivetKit - Create hooks for React
• useActor - Hook for actor instances

Need More Than the Client?

If you need more about Rivet Actors, registries, or server-side RivetKit, add the main skill:

npx skills add rivet-dev/skills

Then use the rivetkit skill for backend guidance.