@calimero-network/mero-react

React bindings for @calimero-network/mero-js — the Calimero Network SDK.

No UI components. No styled-components. No axios. Just a provider, hooks, and storage helpers.

Installation

pnpm add @calimero-network/mero-react @calimero-network/mero-js

Peer dependencies: react ^18 || ^19, react-dom ^18 || ^19.

Quick start

import { MeroProvider, useMero, useExecute, useSubscription, AppMode } from '@calimero-network/mero-react';

function App() {
  return (
    <MeroProvider mode={AppMode.SingleContext} packageName="com.calimero.my-app">
      <MyApp />
    </MeroProvider>
  );
}

function MyApp() {
  const { isAuthenticated, connectToNode, logout, contextId, contextIdentity } = useMero();

  if (!isAuthenticated) {
    return <button onClick={() => connectToNode('http://localhost:4001')}>Connect</button>;
  }

  return <Dashboard />;
}

function Dashboard() {
  const { contextId, contextIdentity } = useMero();
  const { execute, loading } = useExecute(contextId, contextIdentity);
  const [items, setItems] = useState([]);

  // Real-time updates via SSE
  useSubscription(
    contextId ? [contextId] : [],
    () => fetchItems(),
  );

  const fetchItems = async () => {
    const data = await execute('list');
    if (data) setItems(data);
  };

  const addItem = async (title: string) => {
    await execute('add', { title });
    await fetchItems();
  };

  return (
    <div>
      {loading && <p>Loading...</p>}
      {items.map(item => <div key={item.id}>{item.title}</div>)}
      <button onClick={() => addItem('New item')}>Add</button>
    </div>
  );
}

API reference

<MeroProvider>

Wraps your app with a MeroJs instance, auth state, and SSE connectivity.

<MeroProvider
  mode={AppMode.SingleContext}    // required
  packageName="com.calimero.my-app"  // for package-based apps
  timeoutMs={30000}                  // optional, default 30s
>
  {children}
</MeroProvider>

Props (MeroProviderConfig & { children }):

Prop	Type	Required	Description
mode	AppMode	Yes	SingleContext, MultiContext, or Admin
packageName	string	No	Package name for registry/node lookup
packageVersion	string	No	Specific version (defaults to latest)
registryUrl	string	No	Registry URL override
timeoutMs	number	No	HTTP request timeout (default 30000)

Modes and their permissions:

Mode	Permissions	Use case
SingleContext	context:execute	Apps that work with one context
MultiContext	context:create, context:list, context:execute	Apps managing multiple contexts
Admin	admin	Admin dashboards, dev tools

Auth flow: when connectToNode(url) is called, the provider redirects to the node's auth page. After login, the node redirects back with tokens in the URL hash. The provider processes these once (StrictMode-safe via ref) and sets isAuthenticated = true.

Online detection: the provider opens an SSE connection to the node after auth. isOnline reflects the SSE connection state — no polling.

useMero()

Access the MeroJs instance, auth state, and actions.

const {
  mero,             // MeroJs | null — the SDK instance
  isAuthenticated,  // boolean
  isOnline,         // boolean — SSE connection state
  isLoading,        // boolean — initial session restore
  nodeUrl,          // string | null
  applicationId,    // string | null — resolved from auth callback
  contextId,        // string | null — from auth callback
  contextIdentity,  // string | null — executor public key from auth callback
  connectToNode,    // (url: string) => void — starts auth redirect
  logout,           // () => void — clears tokens and state
} = useMero();

Through mero you access the full MeroJs API:

// Admin API (flat methods, NOT nested)
await mero.admin.healthCheck();
await mero.admin.getContexts();
await mero.admin.getContext(contextId);
await mero.admin.getContextIdentitiesOwned(contextId);
await mero.admin.listApplications();
await mero.admin.getApplication(appId);
await mero.admin.installApplication(request);
await mero.admin.createContext(request);
await mero.admin.uploadBlob(request);
await mero.admin.getPeersCount();

// Auth API
await mero.auth.getProviders();
await mero.auth.generateTokens(request);
await mero.auth.refreshToken(request);

// RPC
await mero.rpc.execute({ contextId, method, argsJson, executorPublicKey });

// SSE events
mero.events.connect();
mero.events.subscribe(contextIds);
mero.events.on('event', handler);

// Tokens
mero.getTokenData();        // { access_token, refresh_token, expires_at } | null
mero.isAuthenticated();     // boolean

useExecute(contextId, executorId)

Wraps mero.rpc.execute() with loading/error state. Unmount-safe.

const { execute, loading, error } = useExecute(contextId, contextIdentity);

// Generic typed
const todos = await execute<Todo[]>('list');
await execute('add', { title: 'Buy milk' });
await execute('toggle', { id: '1' });

Return	Type	Description
execute	<T>(method, params?) => Promise<T | null>	Call a contract method
loading	boolean	Request in flight
error	Error | null	Last error

useSubscription(contextIds, callback)

Manages SSE event subscription lifecycle. StrictMode-safe — connects once per MeroJs instance, cleans up on unmount.

useSubscription(
  contextId ? [contextId] : [],
  (event) => {
    console.log('Context event:', event.contextId, event.data);
    refreshData();
  },
);

Param	Type	Description
contextIds	string[]	Context IDs to subscribe to (empty array = no subscription)
callback	(event: SseEventData) => void	Called on each context event

The SSE connection is shared — multiple useSubscription hooks reuse the same connection. The first one to mount calls connect(), subsequent ones just add handlers.

useContexts(applicationId?)

Fetches contexts from the node, optionally filtered by application ID.

const { contexts, loading, error, refetch } = useContexts(applicationId);

// contexts: Array<{ contextId: string; applicationId: string }>

Storage helpers

Persist/read node URL, application ID, context ID, and context identity in localStorage.

import {
  getNodeUrl, setNodeUrl, clearNodeUrl,
  getApplicationId, setApplicationId, clearApplicationId,
  clearAllStorage,
} from '@calimero-network/mero-react';

These are used internally by MeroProvider but exported for apps that need direct access.

Re-exports from mero-js

mero-react re-exports everything from mero-js via export * from '@calimero-network/mero-js'. Any new API added to mero-js is automatically available from mero-react — no manual sync needed.

// All of these work from a single import
import {
  MeroProvider, useMero, useExecute, useSubscription,  // react
  MeroJs, RpcClient, SseClient, WsClient,              // core
  parseAuthCallback, buildAuthLoginUrl,                  // auth helpers
  LocalStorageTokenStore, MemoryTokenStore,              // token stores
} from '@calimero-network/mero-react';

Enums

AppMode.SingleContext   // 'single-context'
AppMode.MultiContext    // 'multi-context'
AppMode.Admin           // 'admin'

ConnectionType.Custom   // 'custom'
ConnectionType.Local    // 'local'
ConnectionType.Remote   // 'remote'

Types

import type {
  MeroContextValue,      // useMero() return type
  MeroProviderConfig,    // MeroProvider props (without children)
  MeroProviderProps,     // MeroProvider props (with children)
  CustomConnectionConfig,// { type: ConnectionType.Custom, url: string }
  AppContext,            // { contextId, executorId, applicationId }
  ExecutionResult,       // { success, result?, error? }
} from '@calimero-network/mero-react';

Full exports list

// Provider & hooks (mero-react)
MeroProvider, useMero, MeroContext
useExecute, useSubscription, useContexts

// Enums (mero-react)

// Types (mero-react)
MeroContextValue, MeroProviderConfig, MeroProviderProps
CustomConnectionConfig, AppContext, ExecutionResult

// Storage (mero-react)
localStorageTokenStorage
getNodeUrl, setNodeUrl, clearNodeUrl
getApplicationId, setApplicationId, clearApplicationId
clearAllStorage

// Everything from @calimero-network/mero-js (auto re-exported)
MeroJs, createMeroJs, MeroJsConfig, TokenData
RpcClient, RpcError, ExecuteParams
SseClient, SseEventData, WsClient, WsEventData
AuthApiClient, AdminApiClient
LocalStorageTokenStore, MemoryTokenStore, TokenStore
parseAuthCallback, buildAuthLoginUrl, AuthCallbackResult, AuthLoginOptions
WebHttpClient, HttpClient, HTTPError
// ...and all other mero-js exports

License

MIT