Feature Flags API
A feature flags API exposes boolean or multivariate toggles that control which code paths or UI variants run for each user or session. Clients or edge BFFs fetch flag evaluations at startup or on interval to enable gradual rollouts and experiments without redeploying apps.
Technical Architecture & Deep-Dive
Flag providers such as PostHog or LaunchDarkly offer HTTP APIs listing enabled features for a user context. Mobile apps should not call every provider directly: a BFF can merge identity from Clerk with flags from analytics tools and return one slim JSON object.
Pairing feature flags with canary API routing lets you enable new endpoints only for cohorts already seeing the updated UI, keeping server and client experiments aligned.
Key Architectural Benefits
Implement Feature Flags API at the Edge
Deploy lightweight API aggregation, edge caching, and secret injection in minutes without Docker containers or complex servers.
Frequently Asked Questions
Q:Should flags be evaluated on the client or server?
Sensitive gating belongs on the server or edge. Client flags are fine for cosmetic UI when secrets are not involved.
Related Architecture Concepts
A canary API release routes a small percentage of traffic to a new implementation while the majority stays on the proven version. Operators watch errors, latency, and business metrics before promoting the canary to receive all traffic or rolling it back.
Backend for Frontend (BFF) is an architectural pattern where a dedicated gateway layer is created for a specific frontend client (e.g., iOS, Android, React). Instead of clients calling multiple generic backend APIs, the edge BFF aggregates upstream calls, injects credentials, and strips unneeded payload fields before transmission.
API versioning is the practice of managing changes to an API so existing clients keep working when the provider introduces breaking changes. Common strategies include version numbers in the URL path, custom headers, and date-based versions like those used by Stripe.
An API Gateway is a single entry point that sits between client applications and backend services. It routes requests, enforces authentication and rate limits, transforms payloads, and aggregates responses so clients talk to one stable endpoint instead of many internal APIs.
Ready-to-Use Edge Recipes
To solve merge clerk user profile with posthog feature flags, never execute unauthenticated requests or embed private tokens directly in client bundles. RealComposer acts as a sub-10ms edge gateway running on Cloudflare Workers that securely injects credentials from your Secret Vault, normalizes responses, and prevents unauthorized API usage. Route calls through your RealComposer edge URL to guarantee complete privacy, robust origin validation, and low mobile latency.
To combine intercom with posthog user events, use one RealComposer pipeline with parallel steps. Intercom conversation list plus PostHog person properties in one payload. Your React app makes one request instead of several sequential upstream calls.
To solve backend for frontend without express or docker, never execute unauthenticated requests or embed private tokens directly in client bundles. RealComposer acts as a sub-10ms edge gateway running on Cloudflare Workers that securely injects credentials from your Secret Vault, normalizes responses, and prevents unauthorized API usage. Route calls through your RealComposer edge URL to guarantee complete privacy, robust origin validation, and low mobile latency.