API Versioning Migration Strategies

Expert

Plan and execute a migration from Data API v1 to v2 (or a future version) without breaking existing clients, using parallel routing, gradual rollout, and deprecation signals.

What you'll learn

How to run v1 and v2 code paths in parallel during migration
How to use deprecation headers to signal clients
How to use feature flags to migrate a percentage of traffic
How to verify v2 parity before retiring v1

Migrating an integration from one API version to another while keeping existing clients working requires a strategy beyond "update the URL." Parallel routing, feature flags, and deprecation headers let you move clients incrementally without a coordinated cutover event.

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Parallel routing in your middleware

During migration, your middleware can route to v1 or v2 based on a request header or environment variable. This lets you test v2 with internal traffic before switching production clients.

FileMaker Script

const FM_VERSION = req.headers.get('x-fm-api-version') ?? process.env.FM_API_VERSION ?? 'v1';
const base = `${FM_HOST}/fmi/data/${FM_VERSION}/databases/${DB}`;

// Internal test clients send: x-fm-api-version: v2
// Production clients use default (v1) until migration is complete

Building a TypeScript SDK Wrapper for the FileMaker Data API Integrating FileMaker with Zapier and Make