react-native-streamdown

This project is not affiliated with, endorsed by, or sponsored by Vercel.

A streaming-ready markdown component for React Native built on top of react-native-enriched-markdown and remend.

It processes raw, incomplete markdown (as it streams token-by-token from an LLM) in the background using react-native-worklets powerful concurrency feature - the Bundle Mode - keeping the JS thread free at all times.

Features

• Renders incomplete streaming markdown correctly — no visual glitches mid-stream
• Background thread processing via react-native-worklets Bundle Mode
• LaTeX support with streaming completion — applied automatically, no configuration needed
• CommonMark and GitHub Flavored Markdown rendering powered by react-native-enriched-markdown with built-in streamingAnimation
• Customizable via remendConfig

Installation

yarn add react-native-streamdown

Peer dependencies

yarn add react-native-enriched-markdown react-native-worklets remend

| Package | Version | | -------------------------------- | ------- | | react-native-enriched-markdown | >=1.0.0 | | react-native-worklets | >=0.10.0 | | remend | 1.3.0 |

Required setup — Bundle Mode

react-native-streamdown runs markdown processing on a worklet thread using Bundle Mode from react-native-worklets. This requires extra configuration steps from the official Bundle Mode setup guide. Make sure to complete these steps before continuing. For a real-world reference of an app configured with Bundle Mode, check out the Bundle Mode Showcase App.

1. babel.config.js — configure Worklets Babel plugin

react-native-streamdown requires special options to be added to the Worklets Babel plugin config in babel.config.js, namely bundleMode: true and importForwarding.moduleNames: ['remend']. Your final config could look like this:

Expo

module.exports = function (api) {
  api.cache(true);

  return {
    presets: ['babel-preset-expo'],
    plugins: [
      [
        'react-native-worklets/plugin',
        {
          bundleMode: true,
          // other options...
          importForwarding: {
            moduleNames: ['remend'], // add this line
          },
        },
      ],
    ],
  };
};

React Native CLI

const workletsPluginOptions = {
  bundleMode: true,
  // other options...
  importForwarding: {
    moduleNames: ['remend'], // add this line
  },
};

importForwarding.moduleNames: ['remend'] tells the Babel plugin to forward the remend import into the generated worklet so it can be called off the JS thread. See the import forwarding docs for details.

2. metro.config.js — configure Metro for monorepos

react-native-worklets Bundle Mode generates files on the fly that might not be tracked by Metro in some monorepo setups. It might also shadow your resolving function. If you're running into issues with module resolution, use getBundleModeMetroConfig (which preserves your existing resolveRequest) and watch the .worklets/ output directory in your metro.config.js:

Expo

const { getDefaultConfig } = require('expo/metro-config');
const {
  getBundleModeMetroConfig,
} = require('react-native-worklets/bundleMode');

const config = getDefaultConfig(__dirname);

// Watch the .worklets/ output directory
config.watchFolders.push(
  require('path').resolve(
    __dirname,
    'node_modules/react-native-worklets/.worklets'
  )
);

module.exports = getBundleModeMetroConfig(config);

React Native CLI

const { getDefaultConfig } = require('@react-native/metro-config');
const {
  getBundleModeMetroConfig,
} = require('react-native-worklets/bundleMode');

const config = getDefaultConfig(__dirname);

// Watch the .worklets/ output directory
config.watchFolders.push(
  require('path').resolve(
    __dirname,
    'node_modules/react-native-worklets/.worklets'
  )
);

module.exports = getBundleModeMetroConfig(config);

3. Patch Metro for synchronous worklet indexing (recommended)

Bundle Mode isolates worklets into separate modules on the fly. Metro builds its file map when it starts, so it can fail to index these freshly generated modules in time — you'll see Failed to get the SHA-1 for .../.worklets/<id>.js and need to reload the app a few times before the bundle succeeds.

To avoid this, patch Metro to allow synchronous indexing of the new modules, as described in the Worklets Bundle Mode setup guide. This repository's example/ app applies such a patch via resolutions — use it as a reference.

Without the patch the app still works, but expect a few extra reloads on first launch while Metro catches up. The one-shot react-native bundle command (offline release bundling) requires the patch.

Usage

import { StreamdownText } from 'react-native-streamdown';

// markdown can be updated token-by-token as the LLM streams
<StreamdownText markdown={partialMarkdown} />;

Props

StreamdownText accepts all props from EnrichedMarkdownText plus one additional prop:

| Prop | Type | Description | | -------------- | --------------- | ------------------------------------------------------------------------------------------------------------------------------------------- | | remendConfig | RemendOptions | Optional. Override the default remend processing config. See remend docs for all available options. |

Pass flavor="github" to render GitHub Flavored Markdown.

Example app

The example/ directory in this repository contains a fully working demo app that shows:

• Streaming Markdown Simulator — streams a sample markdown document token-by-token to demonstrate rendering quality and the streamingAnimation effect
• LLM Streaming Demo — connects to the OpenAI Chat Completions API via SSE and renders the response live using StreamdownText

It is a practical reference for the full Bundle Mode setup (Babel, Metro, package.json flags) and for how to wire StreamdownText into a real streaming UI.

Built by Software Mansion.

License

MIT