OpenAPI Spec Diff Checker
Compare two OpenAPI/Swagger JSON specs and report added, removed, and modified endpoints with breaking-change flags. Instant, private, in your browser.
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What is OpenAPI Spec Diff Checker?
The OpenAPI Spec Diff Checker compares two OpenAPI/Swagger JSON specs endpoint by endpoint, reporting added and removed methods with breaking-change flags. The result is a sorted change report computed instantly in your browser.
Key Benefits
- Endpoint-level comparison with HTTP method badges
- Breaking-change flags for removed endpoints
- Sorted output for readable change reports
- Private by design - specs stay on your device
Common Use Cases
- •Reviewing API changes before a version release
- •Validating that refactoring did not break the contract
- •Generating changelogs from spec version diffs
- •Checking backward compatibility between API versions
- •Auditing third-party API updates
Compare OpenAPI Specs
- Paste spec A: Paste the old OpenAPI JSON spec into the left editor.
- Paste spec B: Paste the new OpenAPI JSON spec into the right editor.
- Read the diff: Added and removed endpoints are listed alphabetically with HTTP method badges.
- Watch for breaking changes: Removed endpoints are flagged as breaking changes that require client-side updates.
Key Features
- Compares two OpenAPI/Swagger JSON specs endpoint by endpoint
- Detects added, removed, and modified methods per path
- Breaking-change flags for removed endpoints and methods
- Sorted output for readable change reports
- Live comparison on every keystroke
- Fully client-side - specs stay on your device
Frequently Asked Questions
What spec format does it support?
It parses JSON-formatted OpenAPI/Swagger specs (OpenAPI 2.0, 3.0, 3.1). YAML users should convert to JSON first using any YAML-to-JSON converter.
What counts as a breaking change?
An endpoint or HTTP method that existed in spec A but is removed in spec B. Breaking changes require client-side updates and should be versioned carefully.
Does it compare schemas and parameters?
It compares endpoint-level availability (path + method). Deep schema and parameter comparison within each endpoint is planned for a future version.
Is my API spec uploaded?
No. Both specs are parsed and compared entirely in your browser. Your API structure never leaves your device.