OpenAPI Change Guard

A dependency-free .NET 10 CLI that flags a focused set of breaking changes between two OpenAPI 3 JSON documents.

This is a synthetic engineering lab using deliberately small example specs. It contains no private API definition or customer material.

Detects

• removed paths and HTTP operations;
• removed published responses;
• removed schemas and properties;
• previously optional properties becoming required;
• property type changes.

Run

dotnet build src/OpenApiChangeGuard/OpenApiChangeGuard.csproj --configuration Release
dotnet run --project tests/OpenApiChangeGuard.Tests/OpenApiChangeGuard.Tests.csproj --configuration Release
dotnet run --project src/OpenApiChangeGuard/OpenApiChangeGuard.csproj -- examples/baseline.json examples/candidate-breaking.json

The tool intentionally fails with exit code 1 when breaking changes are found, making it usable as a CI gate. It is not a complete OpenAPI compatibility engine; the README states its exact boundary so results remain explainable.

Built by Marvin K., a senior ERP/full-stack engineer with extensive API and integration experience. Profile: https://marvin.mk1.rocks