mercurius-js/mercurius

Health v2 · maintenance only

Adoption not part of the score

2484 stars · 253 forks observed · 2026-08-28

What it is AI-extracted, prompt v1, taxonomy v1, 2026-08-30, confidence not recorded

Mercurius is a GraphQL adapter for the Fastify web framework for Node.js, providing query parsing/validation caching, JIT execution, subscriptions, and loader-based batching. It also supports federation and gateway composition via companion plugins.

Use cases

• build a graphql api server in nodejs
• add graphql to an existing fastify app
• set up graphql subscriptions over websockets
• compose a federated graphql gateway from multiple services
• avoid n+1 queries with dataloader-style loaders
• support batched and persisted graphql queries
• optimize graphql execution with jit compilation

When to choose

• you use Fastify and want a performant, well-integrated GraphQL layer
• you need subscriptions, federation, or gateway composition in Node.js
• you want query caching, batching, and JIT execution out of the box

When to avoid

• you use Express, Koa, or another non-Fastify framework
• you need a standalone GraphQL server without Fastify
• your stack is not JavaScript/Node.js

Facets

library · maturity stable

graphql web-framework middleware websocket caching http-server web-development backend apis developer-tools cross-platform fastify graphql-server federation gateway subscriptions jit-compiler batched-queries persisted-queries nodejs web-server

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