---
title: Browser and React Native | Letta Docs
description: Use the portable client entry point in browser, Expo, and React Native applications
---

Use the portable `/client` entry point in browser, Expo, and React Native applications. It includes the cloud and remote transports without importing Node process-management modules:

```
import { LettaAgentClient } from "@letta-ai/letta-agent-sdk/client";


const client = new LettaAgentClient({
  backend: "cloud",
  apiKey: userProvidedApiKey,
  webSocketAuth: "query",
});
```

## What the portable entry supports

| Capability                           | Portable `/client` entry  | Node package root |
| ------------------------------------ | ------------------------- | ----------------- |
| `backend: "cloud"`                   | ✅                         | ✅                 |
| `backend: "remote"`                  | ✅                         | ✅                 |
| `backend: "local"`                   | ❌                         | ✅                 |
| MCP servers (`mcpServers`)           | ❌                         | ✅                 |
| Client tools (`tools`)               | ✅                         | ✅                 |
| Repositories (`client.repositories`) | ✅                         | ✅                 |
| `imageFromFile` helper               | ❌ (use `imageFromBase64`) | ✅                 |

Import from the package root in Node.js when you need `backend: "local"`, which starts and manages a local App Server subprocess, or MCP servers, which run in the SDK’s Node process.

## Browser authentication

Browser WebSockets cannot set upgrade headers, so cloud clients in the browser should use `webSocketAuth: "query"` to send credentials in the connection URL instead:

```
const client = new LettaAgentClient({
  backend: "cloud",
  apiKey: userProvidedApiKey,
  webSocketAuth: "query",
});
```

An API key shipped to the browser is visible to the user. Issue short-lived, user-scoped credentials from your backend rather than embedding an organization-wide key in client code.

## React Native

For an authenticated remote App Server in React Native, adapt the platform WebSocket constructor so the SDK can pass the `Authorization` header:

```
import {
  LettaAgentClient,
  createReactNativeWebSocketConstructor,
} from "@letta-ai/letta-agent-sdk/client";


const client = new LettaAgentClient({
  backend: "remote",
  url: appServerUrl,
  authToken: appServerToken,
  WebSocket: createReactNativeWebSocketConstructor(WebSocket),
});
```

## Sending messages from portable clients

Sessions work the same as in Node: create or resume a session, send, and stream. See [Sending messages](/agent-sdk/messages/index.md) for the full event-handling patterns.

```
await using session = client.resumeSession(agentId);


await session.send("Summarize my unread updates.");


for await (const message of session.stream()) {
  if (message.type === "assistant") process.stdout.write(message.content);
}
```

For images, use `imageFromBase64` or `imageFromURL`; the file-reading helper is Node-only.