Definition
Imagine you’re a landlord who needs to demolish an old building to construct a new one. You wouldn’t just show up one morning with a wrecking ball - you’d give tenants months (or years) of notice, help them find new apartments, provide moving assistance, and only proceed with demolition after everyone has safely relocated. A deprecation policy is exactly this kind of thoughtful transition plan, but for APIs. It’s the formal agreement between an API provider and its users about how old features will be phased out, how much warning will be given, and what support will be provided during the transition.
Without a clear deprecation policy, API consumers live in constant fear. Will the endpoint they depend on suddenly disappear? Will their application break without warning? A good deprecation policy eliminates this anxiety by establishing predictable rules. It typically includes: how much advance notice will be given (often 6-24 months), how the deprecation will be communicated (email, API response headers, developer portal announcements), what migration path or alternative will be provided, and the exact date when the old API will stop working (called the “sunset date”). Major API providers like Google, Microsoft, and AWS publish their deprecation policies prominently, treating them as binding commitments to their developer communities.
A deprecation policy is fundamentally about respect for your users’ time and investment. When developers build applications on your API, they’re making a bet that their code will keep working. The deprecation policy is your promise about the rules of that bet - not that things will never change, but that changes will be communicated fairly and transitions will be managed responsibly. The best policies give developers confidence that they won’t wake up to broken applications, and that when changes do come, they’ll have adequate time and resources to adapt.
Example
Real-World Scenario 1: Google Cloud’s 12-Month Policy Google Cloud APIs follow a strict deprecation policy: at least 12 months notice before any breaking change, with clear migration documentation provided at announcement time. When Google deprecated their Cloud ML Engine in favor of Vertex AI, they announced it in January 2023 with a sunset date of January 2025, giving teams two full years to migrate. Throughout this period, the ML Engine continued working normally, migration guides were published, and support teams helped with transitions.
Real-World Scenario 2: Stripe’s Rolling Window Stripe keeps API versions available for years and uses a deprecation policy that guarantees backward compatibility within major version lines. When they deprecated certain card token APIs, they sent email notifications 18 months in advance, added deprecation warnings to API responses, highlighted the change in their developer dashboard, and provided code examples for the new approach. The old method kept working until the sunset date, with increasingly prominent warnings as the date approached.
Real-World Scenario 3: Facebook Graph API Versioning Facebook (Meta) has a two-year deprecation policy for Graph API versions. When they release version 18.0, version 16.0 (released two years earlier) enters its sunset period. Developers get automated emails, dashboard warnings, and the affected API calls start returning deprecation headers. The policy is predictable: you know that any version will work for at least two years after release, giving you a clear planning horizon.
Real-World Scenario 4: Twilio’s Gradual Phase-Out When Twilio deprecated their original Programmable Voice API in favor of a new architecture, they implemented a multi-stage deprecation: Month 0 - announcement and migration guide; Month 6 - warning headers added to responses; Month 12 - emails to all affected accounts; Month 18 - feature freeze on old API; Month 24 - sunset with 410 Gone responses. Each stage was clearly communicated, giving developers multiple touchpoints to plan their migration.
Analogy
The Road Closure Announcement: When a city needs to close a major highway for reconstruction, they don’t just put up barriers overnight. There are signs months in advance: “Highway 101 closing August 2025. Use alternate route via Highway 85.” Temporary detour routes are built. Traffic updates are broadcasted. Local businesses are notified. Only after extensive preparation does the actual closure happen. API deprecation policies work identically - they’re the advance warning system that lets everyone prepare.
The Store Relocation Notice: When your favorite store moves to a new location, good businesses give you plenty of notice. They put signs in the old location, send emails to loyalty members, update their website, and often operate both locations briefly. They don’t just lock the doors one day. A deprecation policy is this moving notice for APIs - telling users where to go, when the old location closes, and ensuring a smooth transition.
The Graduation Timeline: Schools don’t suddenly graduate students - there’s a clear timeline. Freshman year, you know when you’ll graduate. Colleges publish catalogs saying “this curriculum is valid for students entering 2024-2028.” If requirements change, existing students are “grandfathered” under the old rules. API deprecation policies provide similar guarantees - once you’re using version X, you know the rules that apply to you.
The Prescription Drug Phase-Out: When pharmaceutical companies discontinue medications, there’s a heavily regulated process. Doctors are notified months in advance. Patients are transitioned to alternatives. Pharmacies stock enough supply for the transition period. No one suddenly finds their prescription unavailable. This careful, regulated approach is exactly what a good API deprecation policy provides to the software world.
Code Example
// [Deprecation](https://reference.apios.info/terms/deprecation/) headers (RFC 8594)
GET /v1/products
[HTTP/1.1](https://reference.apios.info/terms/http-1-1/) 200 OK
Deprecation: true
Sunset: Sat, 31 Dec 2025 23:59:59 GMT
Link: <https://api.company.com/v2/products>; rel="successor-version"
Link: <https://docs.company.com/migration>; rel="deprecation"
Warning: 299 - "API v1 deprecated, migrate to v2 by 2025-12-31"
// Deprecation endpoint
GET https://api.company.com/deprecations
{
"deprecations": [
{
"endpoint": "/v1/products",
"version": "1.0",
"announcedDate": "2024-06-01",
"sunsetDate": "2025-12-31",
"reason": "Replaced by more efficient v2 with pagination",
"migrationGuide": "https://docs.company.com/v1-to-v2",
"successorEndpoint": "/v2/products",
"breakingChanges": [
"Response now paginated",
"New authentication required"
],
"supportContact": "[email protected]"
}
]
}
// Typical deprecation timeline
// Month 0: Announce deprecation, publish migration guide
// Month 3: Add deprecation warnings to responses
// Month 6: Email all API consumers
// Month 9: Start returning 299 warnings
// Month 12: Sunset date - return 410 Gone
GET /v1/products
HTTP/1.1 410 Gone
{
"error": "EndpointGone",
"message": "This endpoint was sunset on 2025-12-31",
"successor": "https://api.company.com/v2/products"
}