GraphQL Inspector

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Introduction

GraphQL Inspector outputs a list of changes between two GraphQL schemas. Every change is explained and marked as breaking, non-breaking or dangerous, according to the README. It also validates documents and fragments against a schema, finds similar or duplicated types, and computes schema coverage based on operations.

It runs as a CLI, a GitHub Action and a programmatic library, so teams can check schema changes in pull requests. The README points to GraphQL Hive, The Guild’s schema registry and monitoring platform, for teams wanting a hosted workflow.

For GraphQL APIs it plays the role oasdiff plays for OpenAPI: a compatibility gate between schema versions.

In the quality loop it is a contract check at the API and release stages.

The source code is at graphql-hive/graphql-inspector on GitHub under the MIT licence, with about 1,800 stars; the most recent commit was on 20 October 2026.

Features

1. Schema diff: Breaking, dangerous and safe changes.
2. Operation validation: Check queries and fragments against a schema.
3. Coverage: Measure schema coverage from operations.
4. Similar types: Find duplicated or similar types.
5. CLI and GitHub Action: Run in pipelines and pull requests.

Pros

1. Prevents breaking clients: Catches risky schema changes early.
2. Free to use: Open source under the MIT licence, so the core tool costs nothing to use.
3. Actively maintained: The repository had commits as recent as 20 October 2026.

Cons

1. GraphQL only: Not for REST or gRPC.
2. Static checks: Does not test resolvers.

Usage and Links (Example)

npx @graphql-inspector/cli diff old-schema.graphql new-schema.graphql

Resources:

• GraphQL Inspector website
• GitHub repository

Pricing

GraphQL Inspector is free and open source under the MIT licence.

Recommended for?

1. Teams publishing GraphQL APIs.
2. Not a fit for REST-only APIs.

Conclusion

GraphQL Inspector is a focused, maintained compatibility checker for GraphQL schemas.

On CheckOps, GraphQL Inspector is filed under the API & contract testing and Release & CI gates stages. Related tools listed here include oasdiff, Spectral, Hoppscotch, Pact, Specmatic and Postman. Before choosing, compare them on licence, supported languages and platforms, hosting model, and how well each fits your existing CI pipeline. Facts on this page were checked against the official website, documentation and repository on 11 November 2026; statements the vendor makes about its own product are marked as vendor claims.