# Mero.js

> The pure-JavaScript SDK for Calimero: authenticate to a node, drive the
> admin API, execute WASM contract methods over JSON-RPC, and stream
> real-time events over SSE/WebSocket. Zero dependencies — built on fetch,
> EventSource, WebSocket, and AbortController; runs in the browser, Node 18+,
> and edge runtimes.

Docs site: https://calimero-network.github.io/mero-js/

## Get Started — install, authenticate, and make your first call

- [Quickstart](https://calimero-network.github.io/mero-js/get-started/quickstart/): Install Mero.js, connect to a node, authenticate, and make your first admin and RPC calls — in a few minutes.
- [Authentication](https://calimero-network.github.io/mero-js/get-started/authentication/): The three ways to authenticate — username/password, Desktop SSO callback, and the login-redirect flow — plus how the SDK manages the JWT token lifecycle for you.

## Understand — the SDK architecture, token lifecycle, and glossary

- [System Overview](https://calimero-network.github.io/mero-js/understand/system-overview/): How Mero.js is structured — the MeroJs facade, the transport layer, the API and event clients, lazy initialisation, and the zero-dependency Web-Standards foundation.
- [Glossary](https://calimero-network.github.io/mero-js/understand/glossary/): The Calimero and Mero.js terms that show up across these docs — node, context, namespace, group, application, blob, RPC, capabilities, keys, and TEE.

## Guides — contexts & apps, RPC, subscriptions, groups, blobs, transport, HA

- [Contexts & Applications](https://calimero-network.github.io/mero-js/guides/contexts-and-apps/): Install an application, create a context, generate an identity, and join — the core admin-API lifecycle, driven from Mero.js.
- [Executing Methods](https://calimero-network.github.io/mero-js/guides/executing-methods/): Run WASM contract methods in a context with the RPC client — arguments, typed return values, RpcError handling, and the migration helpers.
- [Subscriptions](https://calimero-network.github.io/mero-js/guides/subscriptions/): Stream real-time context events from the node over Server-Sent Events (recommended) or WebSocket — connect, subscribe, and handle events.
- [Groups & Governance](https://calimero-network.github.io/mero-js/guides/groups-and-governance/): Namespaces, groups, members and roles, the capability bitmask, metadata, and the TEE admission policy — driven from the admin API.
- [Blobs](https://calimero-network.github.io/mero-js/guides/blobs/): Upload, list, download, inspect, and delete binary blobs on a node through the admin API.
- [HTTP Transport](https://calimero-network.github.io/mero-js/guides/http-transport/): Use the low-level fetch-based HttpClient directly — factories, response parsing, retry with backoff, signal composition, FormData, custom fetch, and credentials.
- [High Availability](https://calimero-network.github.io/mero-js/guides/high-availability/): Enable or disable cloud-managed TEE high availability for a context using the redirect-based CloudClient.
- [Bundling & runtimes](https://calimero-network.github.io/mero-js/guides/bundling-and-runtimes/): How the package ships (ESM, CJS, and a browser build), how it tree-shakes, which runtimes support which features, and the browser-only gotchas (CORS, SSR).
- [Writing without a node, end to end](https://calimero-network.github.io/mero-js/guides/delegated-execution/): The full path from a Google sign-in to a keyholder's first write through a hosted TEE relay — who has to do what, in what order, and which step surprises people.
- [One app, two transports](https://calimero-network.github.io/mero-js/guides/one-app-two-transports/): The same application code running against a node you own and a relay you do not — what works today, what does not, and how to tell which you got.
- [Sealed transport](https://calimero-network.github.io/mero-js/guides/sealed-transport/): Encrypt traffic end to end to a TEE node's attested key, with forward secrecy, so a proxy or relay in the path cannot read or forge it.

## Reference — MeroJs, the admin & auth API surface, and the error model

- [MeroJs](https://calimero-network.github.io/mero-js/reference/mero-js/): The MeroJs facade — configuration, property accessors, instance and static methods, and the token types.
- [Admin API](https://calimero-network.github.io/mero-js/reference/admin-api/): The full AdminApiClient surface — every method, its signature, and the node endpoint it calls, grouped by area.
- [Auth API](https://calimero-network.github.io/mero-js/reference/auth-api/): The full AuthApiClient surface — health, identity, providers, token generation and refresh, revocation, and root/client key management.
- [Error Model](https://calimero-network.github.io/mero-js/reference/error-model/): The typed errors the SDK throws — HTTPError, AuthRevokedError, RpcError — and how cancellation and timeouts surface.
- [RPC client](https://calimero-network.github.io/mero-js/reference/rpc/): sdk.rpc (RpcClient) — execute a context's WASM methods over JSON-RPC, plus the owner-driven migration helpers.
- [Events (SSE / WebSocket)](https://calimero-network.github.io/mero-js/reference/events/): sdk.events (SseClient) and sdk.ws (WsClient) — stream real-time context events, subscribe to contexts, and handle reconnection.
- [Cloud client](https://calimero-network.github.io/mero-js/reference/cloud/): CloudClient — sign in to Calimero Cloud, list the namespaces an account owns, discover the TEE relays serving them, and toggle High Availability.
- [Capabilities](https://calimero-network.github.io/mero-js/reference/capabilities/): The member-capability bitmask — the CAPABILITIES bit constants, the CAPABILITY_PRESETS masks, and the capMask / capNames / hasCap / withCap / withoutCap helpers for reading and building capability masks.
- [Relay client](https://calimero-network.github.io/mero-js/reference/relay/): RelayClient — write to a context through a relay, holding nothing but a signing key. Mints a warrant locally and presents it as an intent; the relay executes as your principal.
- [connectCloud](https://calimero-network.github.io/mero-js/reference/connect-cloud/): The second way to log in — sign in to Calimero Cloud instead of connecting to a node, and write through an attested TEE relay.
- [Transport](https://calimero-network.github.io/mero-js/reference/transport/): MeroClient — one client, two write paths. Pick node or relay once at construction; every call site after that is identical.
- [Account roots](https://calimero-network.github.io/mero-js/reference/account-roots/): Mint a Calimero account root with a 24-word recovery phrase, restore one from that phrase, and prove possession of it to Calimero Cloud — all offline, with no node involved.