APIDiffGuard

Concepts

Baselines, diffs, severity levels, ignore rules, and schedules.

Baseline

A baseline is a versioned snapshot of a healthy response:

  • HTTP status code
  • Response headers you care about
  • JSON (or text) body

Only one baseline is active per endpoint. New captures bump the version and deactivate the previous active baseline.

Check

A check fetches the endpoint again and stores the live response. Checks can be triggered from the console, CLI, API, or a schedule.

Diff

A diff compares the active baseline body (and status) to a check result. Changes are classified by severity:

SeverityExamples
BreakingField removed, type changed, status class change
WarningField added, enum growth (configurable)
InfoValue-only churn on non-ignored paths

Ignore rules

Volatile paths (request_id, timestamps, cursors) should be ignored so alerts fire on contract changes — not every unique request.

Schedules

Schedules run checks on an interval (for example hourly). Use them for third-party APIs that change when you are not deploying.

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