# google/rejoiner

Generates a unified GraphQL schema from gRPC microservices and other Protobuf sources

Repository: https://github.com/google/rejoiner
Canonical: https://ross.abutalabs.com/products/rejoiner
Homepage: https://google.github.io/rejoiner/
Language: Java
License: Apache-2.0
License Family: permissive
Topics: graphql-server, protobuf, grpc, graphql
Archived: true
Last push: 2023-06-13T22:58:03+00:00

## Health v2 (maintenance only)
Score: 10/100 (v2, computed 2026-09-03T02:20:16.233290+00:00)
- activity 0, release rhythm 8, longevity 100
- inputs: {"age_days": 3192, "days_push": 1177, "days_rel": null, "gap_med": null, "n_releases_24m": 0}
- flags: archived
- formula: round(0.45*activity + 0.35*rhythm + 0.20*longevity); archived -> min(score, 10)

## Adoption (not part of the score)
Stars 3658, forks 135 (observed 2026-08-28T04:08:13.246334+00:00)

## What it is
A Java library from Google that generates a unified GraphQL schema from gRPC microservices and other Protobuf sources. It maps GraphQL queries to Proto-based requests, joins data sources via annotated methods, and provides a DSL for schema composition.

## Use cases
- expose gRPC microservices through a single GraphQL API
- generate GraphQL types from protobuf definitions
- stitch multiple backend services into one GraphQL schema
- map GraphQL selectors to protobuf field masks
- build a GraphQL gateway over existing proto-based backends
- join data from multiple microservices in one GraphQL query

## When to choose
- your backend is built on gRPC and protobuf services
- you want a unified GraphQL API layer over multiple microservices
- you're on the JVM and want schema generation from proto definitions
- you need field-mask-based partial responses driven by GraphQL queries

## When to avoid
- your services don't use protobuf or gRPC
- you need a actively developed project with recent commits
- you want a non-JVM GraphQL gateway
- you need a full GraphQL server runtime rather than schema generation

## Facets
- artifact type: library
- maturity: maintenance
- function: graphql, rpc, api-framework, middleware
- domain: apis, backend, microservices, web-development, developer-tools
- platform: jvm, cross-platform
- tags: grpc, protobuf, schema-generation, schema-stitching, guice, field-mask, api-gateway

## Member repositories
- google/rejoiner (main) score 10

## Provenance
- Observed fields: from GitHub, fetched 2026-08-28T04:08:13.246334+00:00.
- Health v2: computed from the inputs above; adoption is never an input.
- Inferred fields (summary, facets, guidance): AI-extracted, prompt v1, taxonomy v1, on 2026-08-29T18:31:36.577106+00:00, confidence not recorded.
  - readme: https://github.com/google/rejoiner (fetched 2026-08-28T04:08:13.246334+00:00, sha e568787943bd)
  - homepage: https://google.github.io/rejoiner/ (fetched 2026-08-29T09:25:40.767490+00:00, sha c86c402f5e9c)
- Data as of 2026-08-30T08:39:29.467469+00:00.