API Downtime and Fallback Strategies
Third-party API outages are inevitable — every external dependency is a potential failure point. Designing your integration with fallback strategies ensures that API outages degrade your application gracefully rather than causing complete failures for your users.
Types of Degradation
- Graceful degradation: When an API is unavailable, the feature that depends on it becomes unavailable while the rest of the application continues to function. Users see a clear message rather than a broken experience.
- Fallback content: Serve cached data or default content when the live API is unavailable. A product search might show recent cached results rather than failing entirely.
- Feature flags: Disable features that depend on unavailable APIs — route traffic to a simplified experience.
Circuit Breaker Pattern
A circuit breaker monitors API call failure rates. When failures exceed a threshold, the circuit "opens" — subsequent calls fail immediately without attempting the API. After a timeout, the circuit enters "half-open" state, allowing a test request. If it succeeds, the circuit closes. This prevents cascading failures and reduces load on recovering services.
Caching as a Resilience Strategy
Cache API responses with appropriate TTLs. When the API is unavailable, serve from cache (stale-while-revalidate). Cache hit rate is also a cost optimisation — fewer API calls, lower API costs.
Status Page Monitoring
Subscribe to status pages for your critical third-party APIs — most providers publish these. Tools like Statuspage, Instatus allow providers to communicate incidents. Your monitoring should also independently detect third-party degradation rather than relying solely on provider communication.