Third-Party Integration Cutover Checklist

When to Use This Checklist

Use this checklist when cutting over to a new third-party API or replacing an existing vendor integration, such as a payment, email, or identity provider. External dependencies introduce SLAs, rate limits, and failure modes outside your control, so a careful cutover protects users from disruption and keeps a path back if the new vendor underperforms.

How to Use This Checklist

Begin by inventorying every touchpoint and data flow that depends on the integration, then review the vendor's SLA and rate limits so you know its limits. Build an anti-corruption layer to keep vendor-specific shapes out of your domain, and test thoroughly in the sandbox. Run parallel or canary traffic before full cutover, reconcile data between old and new, and keep a documented rollback path until the new integration proves stable.

What Good Looks Like

A clean cutover starts with a complete inventory and a reviewed SLA. Credentials live in a secret manager with rotation, and an anti-corruption layer isolates the vendor's model. The integration is validated in a sandbox with realistic edge cases and resilient error handling. Traffic shifts gradually via canary or parallel running with data reconciliation, monitoring tracks errors, latency, and cost, and a tested rollback path remains available.

Common Pitfalls

The most damaging mistake is a big-bang switch with no rollback, turning a vendor issue into an outage. Teams underestimate rate limits and quotas, hitting them under production load. Tight coupling to the vendor's data model makes future changes painful, which an anti-corruption layer prevents. Skipping data reconciliation leaves silent inconsistencies. Finally, missing post-cutover monitoring hides cost and reliability regressions.

Related Resources

Review the circuit breaker pattern, secrets management best practices, idempotency keys, API rate limiting, and canary release best practices.