Mercurius
Mercurius is a GraphQL adapter for Fastify used to implement GraphQL servers and gateways.
What Mercurius is
Mercurius is a GraphQL adapter for Fastify used to implement GraphQL servers and gateways. It runs as self-hosted software for JavaScript and TypeScript server environments and includes an API explorer. Query handling caches parsing and validation work, then uses a Just-In-Time compiler through graphql-jit. Automatic loader integration helps avoid 1 + N query patterns. GraphQL features include subscriptions, batched queries, and customizable persisted queries. Federation and gateway implementations are available through @mercuriusjs/federation and @mercuriusjs/gateway, including subscriptions. Listed integrations cover Nexus, TypeGraphQL, GQLoom, Prisma, mercurius-integration-testing, OpenTelemetry, and NestJS. Mercurius is free, offers an MIT-licensed repository, and documents npm and Yarn installation routes. CSRF prevention is included but disabled by default, so configuration must enable it. Security reports can be sent through GitHub Security Advisories or email.
Good
- Free plan available
- Caches parsing and validation
- Supports subscriptions and batched queries
- Automatic loaders reduce 1 + N queries
- Includes federation and gateway support
Watch out
- Self-hosted deployment required
- CSRF prevention disabled by default
- Requires Fastify and GraphQL packages
Who it suits
Mercurius suits developers building GraphQL servers or gateways with Fastify in JavaScript or TypeScript. It is also relevant to teams needing subscriptions, federation, gateway support, or listed ecosystem integrations.
Verdict
Mercurius provides a focused Fastify-based GraphQL stack with performance features, loaders, subscriptions, and federation options. Its self-hosted model and configuration requirements should be considered before adoption.
The facts
Each one read from Mercurius's own pages, with the date it was checked.
What it does
- Federation and gateway
- Federation and gateway support are provided through @mercuriusjs/federation and @mercuriusjs/gateway, including subscriptions.checked 8 Oct 2026
- Federation and gateways
- It supports federation and gateway implementations, including subscriptions.checked 8 Oct 2026
- GraphQL capabilities
- It supports subscriptions, batched queries, and customizable persisted queries.checked 8 Oct 2026
- Installation
- The documented installation command is npm i fastify mercurius graphql, with a Yarn alternative also provided.checked 8 Oct 2026
- Integrations
- The integrations documentation lists Nexus, TypeGraphQL, GQLoom, Prisma, mercurius-integration-testing, OpenTelemetry, and NestJS.checked 8 Oct 2026
- License
- The repository lists the project under the MIT license.checked 8 Oct 2026
- Loaders
- Automatic loader integration is provided to avoid 1 + N queries.checked 8 Oct 2026
- Product
- Mercurius is a GraphQL adapter for Fastify for implementing GraphQL servers and gateways.checked 8 Oct 2026
- Query performance
- It caches query parsing and validation and uses a Just-In-Time compiler via graphql-jit.checked 8 Oct 2026
- Security
- Mercurius includes CSRF prevention, which the documentation says is disabled by default and must be enabled in configuration.checked 8 Oct 2026
- Sponsors
- The project acknowledges NearForm and Platformatic as sponsors.checked 8 Oct 2026
- Support and contribution
- The project describes itself as an open open-source project where significant contributors may receive commit access.checked 8 Oct 2026
- Vulnerability reporting
- The security policy accepts potential vulnerability reports through GitHub Security Advisories or email and specifies a five-business-day initial response target.checked 8 Oct 2026
- What it does
- Mercurius is a GraphQL adapter for Fastify.checked 8 Oct 2026
Money
- Pricing and trial
- The opened project pages state an MIT license but do not publish plan prices or a free-trial duration.checked 8 Oct 2026
Alternatives to Mercurius
- 1
Altair GraphQL Client
Free planWebExtensionLinuxmacOS7.4From $7.99 a month - 2
Apollo Client
Free planAndroidiOSWebAPI7.3From $5 a month - 3
Hasura
Free planWebAPILinuxSelf-hosted6.9Free plan - 4
GraphQL Hive
Free planWebAPISelf-hosted6.7From $20 a month - 5
PostGraphile
Free planWebAPISelf-hosted6.7From $25 a month - 6
WunderGraph Cosmo
Free planWebAPISelf-hosted6.7From $499 a month