Early Hints (103)
Early Hints are HTTP 103 interim responses that carry Link headers so browsers can open connections or fetch critical resources before the server finishes the full response. For web apps, hints can preconnect to an edge BFF host while the origin still assembles JSON, shaving DNS and TLS time off later fetches.
Technical Architecture & Deep-Dive
Early Hints shift connection setup earlier in the page lifecycle. They help most when the HTML shell knows which API host or font CDN will be needed but the dynamic body is still computing.
API-only mobile clients do not consume 103 hints the way browsers do. Native apps should instead warm connections and use a single gateway. At the edge, platforms may emit hints for companion assets while worker logic runs upstream fan-out in parallel.
Key Architectural Benefits
Implement Early Hints (103) at the Edge
Deploy lightweight API aggregation, edge caching, and secret injection in minutes without Docker containers or complex servers.
Frequently Asked Questions
Q:Do Early Hints replace preconnect in HTML?
They complement each other. Hints can be generated dynamically by the server, while link rel preconnect in markup is static but easy to reason about.
Related Architecture Concepts
HTTP keep-alive, or persistent connections, keeps a TCP connection open after a response so subsequent requests to the same host reuse it. This avoids repeating TCP and TLS handshakes for every request, significantly reducing latency for clients that call the same API repeatedly.
TLS handshake latency is the delay caused by negotiating an encrypted HTTPS connection before any application data is sent. The client and server exchange messages to agree on ciphers and verify certificates, costing one or more network round trips on top of TCP setup.
Prefetch and prerender are browser optimizations that download or fully render a likely next navigation before the user clicks. Prefetch typically warms HTML and assets, while prerender goes further by building the page off-screen. Speculative API warming can hide latency when predictions match real user paths.
Time to First Byte (TTFB) measures the time between a client sending an HTTP request and receiving the first byte of the response. It includes DNS lookup, connection setup, TLS negotiation, network travel, and server processing time, making it a core indicator of backend and network responsiveness.
Ready-to-Use Edge Recipes
To solve sub 10ms api response time for mobile apps, 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 solve rest api payload size limit mobile network optimization, 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.