Response Time Checker
Measure the response time and time to first byte (TTFB) for any URL from the server.
About Response Time Testing
Website response time (also called Time to First Byte, or TTFB) is the time from when a client sends an HTTP request to when it receives the first byte of the response. It is a key indicator of server performance and is influenced by DNS resolution time, TCP connection setup, TLS handshake, and server-side processing time.
What affects response time?
- Server location and latency — Geographic distance adds round-trip time. A server in the US will have higher latency for UK users than one in London.
- Server-side processing — Database queries, template rendering, and API calls on the backend all add to TTFB.
- TLS handshake overhead — Each new HTTPS connection requires a TLS handshake (typically 100–300ms extra). TLS session resumption and HTTP/2 reduce this.
- Hosting tier — Shared hosting, VPS, and dedicated servers have significantly different performance profiles. Cold-start serverless functions add initial latency.
Response time benchmarks
- Under 200ms — Excellent. Fast server with good caching.
- 200–500ms — Good for most web applications.
- 500ms–1s — Acceptable but worth investigating for optimisation opportunities.
- Over 1 second — Slow. Likely indicates a missing cache, slow database queries, or an underpowered server.
This tool makes requests from the ToolForge server. Results reflect server-to-server latency, not end-user browser experience which includes CDN edge, DNS, and content download time on top of TTFB.
Frequently asked questions
What is TTFB?
TTFB (Time To First Byte) is the time from making an HTTP request until the first byte of the response is received. It measures server processing time plus network latency and is a key web performance metric.
What is a good TTFB?
Under 200ms is excellent, 200–500ms is acceptable, 500ms–1s is slow, and over 1s is poor. For a good Core Web Vitals score, aim for TTFB under 800ms.