SchemGuard

Detect breaking changes in OpenAPI specs. Use when reviewing API changes, validating PRs that modify API specs, checking backward compatibility, or linting O...

SchemGuard — API Schema Drift Monitor

Quick Start

# Diff two specs (breaking vs non-breaking)
npx @sethclawd/schemaguard diff old.yaml new.yaml

# CI check (exit 0=safe, 1=breaking, 2=error)
npx @sethclawd/schemaguard ci --spec ./openapi.yaml --baseline ./baseline.yaml

# Lint spec quality
npx @sethclawd/schemaguard lint ./openapi.yaml

# JSON output for programmatic use
npx @sethclawd/schemaguard diff old.yaml new.yaml --format json

When to Use

• Before committing changes to an OpenAPI spec
• When reviewing PRs that modify API routes
• After generating/updating OpenAPI specs from code
• Before deploying API changes to production
• Validating that a migration maintains backward compatibility

Breaking Changes Detected

Rule	What It Catches
endpoint-removed	Deleted endpoints
required-param-added	New required parameters
field-type-changed	Changed field types
response-field-removed	Removed response fields
enum-value-removed	Narrowed enums
auth-requirement-changed	Changed security schemes

Non-Breaking (Info Only)

Added endpoints, optional params, response fields, widened enums, deprecations.

MCP Server

For direct tool integration:

npx @sethclawd/schemaguard --mcp

Exposes: schemaguard_diff, schemaguard_lint, schemaguard_check