Introduction

Monitor external REST APIs and MCP server tool catalogs for breaking schema changes — with open-source diff tools, a hosted watchtower, and agent-ready MCP integration.

Welcome to DriftGuard

DriftGuard helps teams catch contract drift on dependencies they do not control: Stripe, GitHub, Slack, vendor OpenAPI specs, and MCP tool lists exposed to Cursor and Claude agents.

  • Watches — scheduled snapshots of an API or MCP endpoint, compared to the last known-good schema.
  • Change records — classified diffs (breaking, warning, info) with remediation hints for humans and agents.
  • Coverage assert — fail CI when discovered dependencies are not watched (Pro+ API key).
  • MCP client — offline compare_json plus hosted tools when DRIFTGUARD_API_KEY is set.

Base URL

https://driftguard.org

Hosted API routes are prefixed with /api/. OpenAPI spec: /openapi.json.

Quick example

curl -s https://driftguard.org/api/watches/suggest \
  -H "Content-Type: application/json" \
  -d '{"urls":["https://api.stripe.com"]}'

Architecture overview

DriftGuard splits into an open-source client (CLI + MCP) and a hosted watchtower (snapshots, alerts, console). See Architecture for the full data flow.

Why contract drift

Agents break when vendor APIs and MCP tool catalogs change — often while HTTP checks stay green. Why contract drift matters →

Next steps

  • Quickstart — first watch in five minutes
  • How-to guides — CI, MCP, and coverage recipes
  • API reference — hosted REST endpoints
  • Core concepts — watches, drift, severity rules