# mercurius

**Repository Path**: trusted-list/mercurius

## Basic Information

- **Project Name**: mercurius
- **Description**: Implement GraphQL servers and gateways with Fastify
- **Primary Language**: Unknown
- **License**: MIT
- **Default Branch**: master
- **Homepage**: https://mercurius.dev/
- **GVP Project**: No

## Statistics

- **Stars**: 0
- **Forks**: 0
- **Created**: 2026-03-18
- **Last Updated**: 2026-04-01

## Categories & Tags

**Categories**: Uncategorized

**Tags**: None

## README

![Mercurius Logo](https://raw.githubusercontent.com/mercurius-js/graphics/main/mercurius-horizontal.svg)

# mercurius

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Mercurius is a [**GraphQL**](https://graphql.org/) adapter for [**Fastify**](https://www.fastify.io)

Features:

- Caching of query parsing and validation.
- Automatic loader integration to avoid 1 + N queries.
- Just-In-Time compiler via [graphql-jit](http://npm.im/graphql-jit).
- Subscriptions.
- Federation support via [@mercuriusjs/federation](https://github.com/mercurius-js/mercurius-federation), including Subscriptions.
- Gateway implementation via [@mercuriusjs/gateway](https://github.com/mercurius-js/mercurius-gateway), including Subscriptions.
- Batched query support.
- Customisable persisted queries.

## Docs

- [Install](#install)
- [Quick Start](#quick-start)
- [Examples](#examples)
- [API](docs/api/options.md)
- [Context](docs/context.md)
- [Loaders](docs/loaders.md)
- [Hooks](docs/hooks.md)
- [Lifecycle](docs/lifecycle.md)
- [Federation](docs/federation.md)
- [Subscriptions](docs/subscriptions.md)
- [Batched Queries](docs/batched-queries.md)
- [Persisted Queries](docs/persisted-queries.md)
- [TypeScript Usage](/docs/typescript.md)
- [HTTP](/docs/http.md)
- [GraphQL over WebSocket](/docs/graphql-over-websocket.md)
- [Integrations](docs/integrations/)
- [Related Plugins](docs/plugins.md)
- [Security - CSRF Prevention](docs/security/csrf-prevention.md)
- [Faq](/docs/faq.md)
- [Acknowledgements](#acknowledgements)
- [License](#license)

## Install

```bash
npm i fastify mercurius graphql
# or
yarn add fastify mercurius graphql
```

The previous name of this module was [fastify-gql](http://npm.im/fastify-gql) (< 6.0.0).

## Quick Start

```js
'use strict'

const Fastify = require('fastify')
const mercurius = require('mercurius')

const app = Fastify()

const schema = `
  type Query {
    add(x: Int, y: Int): Int
  }
`

const resolvers = {
  Query: {
    add: async (_, { x, y }) => x + y
  }
}

app.register(mercurius, {
  schema,
  resolvers
})

app.get('/', async function (req, reply) {
  const query = '{ add(x: 2, y: 2) }'
  return reply.graphql(query)
})

app.listen({ port: 3000 })
```

## Examples

Check [GitHub repo](https://github.com/mercurius-js/mercurius/tree/master/examples) for more examples.

## Acknowledgements

The project is kindly sponsored by:

- [NearForm](https://www.nearform.com)
- [Platformatic](https://platformatic.dev)

The Mercurius name was gracefully donated by [Marco Castelluccio](https://github.com/marco-c).
The usage of that library was described in https://hacks.mozilla.org/2015/12/web-push-notifications-from-irssi/, and
you can find that codebase in https://github.com/marco-c/mercurius.

## License

MIT