HTTP Connectivity Test

Test if any URL is reachable and measure its fetch timing with our free HTTP Connectivity Test. Enter a URL to measure DNS resolution time, TCP handshake duration, TLS negotiation time (for HTTPS), Time to First Byte (TTFB), and total content download time. Results are displayed in an interactive waterfall chart that shows each phase proportionally - no signup required.

Test if a URL is reachable and measure its fetch timing. See DNS resolution, TCP handshake, TLS handshake, Time to First Byte (TTFB), and total load time with an interactive waterfall chart.

URL

Enter a URL to test its connectivity and measure fetch timing (https:// is added automatically if missing).

Quick test:

Why Use Our HTTP Connectivity Test?

Real Browser Fetch Timing

Measure actual fetch timing from your browser to the target server using the Performance Resource Timing API. Get real DNS resolution time, TCP handshake duration, TLS negotiation time, Time to First Byte, and total download time - not estimates or approximations.

Interactive Waterfall Chart

Visualise each phase of the HTTP request in a detailed waterfall chart. See how DNS, TCP, TLS, TTFB, and download phases stack up, with their durations and relative proportions. Quickly identify which phase is the bottleneck in the connection.

Timing-Allow-Origin Detection

Automatically detect whether the target server sends the Timing-Allow-Origin header, which determines if detailed timing information is available for cross-origin requests. When enabled, you get full DNS/TCP/TLS breakdowns. When absent, the tool clearly notes the limitation.

Status Code & Response Analysis

See the HTTP status code, status text, response size, and protocol (HTTP vs HTTPS) for every test. Comprehensive notes explain what each timing metric means and highlight important observations like TLS session resumption, redirects, and timing limitations.

Common Use Cases for HTTP Connectivity Test

Website Latency Debugging

When your website feels slow, use the HTTP Connectivity Test to identify the bottleneck. Check if the issue is DNS resolution time, TCP connection latency, TLS negotiation overhead, or server response time (TTFB). Pinpoint exactly which phase needs optimisation.

CDN & Hosting Provider Comparison

Compare the connectivity performance of different CDN providers or hosting regions. Test URLs from different providers side-by-side to see which one has the lowest TTFB, fastest TLS negotiation, and best overall connection time from your location.

TLS Configuration Verification

Verify that your TLS configuration is optimised for performance. The waterfall chart shows TLS handshake time, helping you assess whether TLS session resumption is working, whether your certificate chain is optimal, and whether your cipher suite configuration is performant.

DNS Performance Monitoring

Monitor DNS resolution times for your domains across different DNS providers. Detect slow DNS lookups that may indicate resolver issues, misconfigured nameservers, or propagation delays that affect your website's initial connection time.

Timing-Allow-Origin Compliance Check

Check if your APIs and third-party services expose the Timing-Allow-Origin header, which is required for detailed cross-origin timing measurements. Ensure your performance monitoring tools can collect accurate timing data for all your external resources.

Global Connectivity Assessment

Assess how well a website or API performs from different network conditions. The browser-based timing reflects real user experience, accounting for local network conditions, DNS resolver performance, and ISP routing that server-side tests cannot measure.

Understanding HTTP Connectivity Testing

What is HTTP Connectivity Testing?

HTTP connectivity testing measures the time it takes for each phase of an HTTP request to complete, from DNS lookup to the final byte received. Unlike ping or traceroute which test network-level connectivity, the HTTP Connectivity Test measures the full application-level request - including DNS resolution, TCP connection establishment, TLS/SSL handshake (for HTTPS), server processing time (TTFB), and content download. This provides a realistic picture of what users actually experience when accessing a website or API.

How Our HTTP Connectivity Test Works

Enter a URL:Type any URL (with or without https://) and click "Test Connectivity". We automatically add https:// if no protocol is specified and send a standard HTTP GET request from your browser.
Timing Measurement: Your browser measures the timing of each request phase using the Performance Resource Timing API. The tool tracks DNS lookup time, TCP connection time, TLS handshake time, Time to First Byte (how long until the server starts responding), and content download time.
Results Visualisation: Timings are displayed in a summary grid and an interactive waterfall chart that shows each phase proportionally. The tool also detects whether the server supports detailed cross-origin timing via the Timing-Allow-Origin header and notes any limitations or observations.

Understanding HTTP Timing Metrics

DNS Lookup: The time to resolve the domain name to an IP address. Fast DNS (1-50ms) indicates efficient DNS resolvers. Slow DNS may indicate resolver issues or misconfigured nameservers.
TCP Handshake: The time to establish a TCP connection (SYN, SYN-ACK, ACK). Typically 10-100ms depending on network latency. Keep-alive connections skip this step.
TLS Handshake: The time to negotiate a secure connection, including certificate exchange and cipher suite negotiation. TLS 1.3 reduces this to a single round trip. Session resumption can make it nearly instant.
TTFB (Time to First Byte): The time from the start of the request to the first byte of the response. This includes network latency and server processing time. Google recommends TTFB under 800ms for good user experience.
Download: The time to receive the response body. Depends on content size, network bandwidth, and compression. Smaller responses with gzip/brotli compression download faster.

Privacy & Cross-Origin Limitations

Our HTTP Connectivity Test sends requests directly from your browser to the target URL. We do not proxy, store, or process your requests on our servers. For cross-origin requests, detailed timing information (DNS, TCP, TLS) is only available if the target server sends the Timing-Allow-Origin response header. Without this header, only TTFB and total time are available. The tool clearly indicates when detailed timing is not available. All data is processed client-side and no request logs are retained.

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Frequently Asked Questions About HTTP Connectivity Test

An HTTP connectivity test measures the time it takes for each phase of an HTTP request - DNS lookup, TCP handshake, TLS handshake, Time to First Byte (TTFB), and content download. Unlike ping which only tests network reachability, an HTTP connectivity test measures the full application-level request that users actually experience when accessing a website.

Enter a URL and click "Test Connectivity". Your browser sends an HTTP GET request to the URL and uses the Performance Resource Timing API to measure the duration of each request phase - DNS lookup, TCP connection, TLS negotiation (if HTTPS), server response time (TTFB), and content download. Results are displayed in a timing grid and waterfall chart.

TTFB (Time to First Byte) measures the time from the start of the request to when the first byte of the response is received. It includes network round-trip time plus server processing time. Google recommends TTFB under 800ms. High TTFB indicates slow server processing, network congestion, or distant server locations.

Detailed DNS, TCP, and TLS timing is only available when the target server sends the Timing-Allow-Origin response header. Without this header, browsers restrict access to these timings for security reasons (to prevent cross-origin timing attacks). For URLs without Timing-Allow-Origin, only TTFB, download time, and total time are shown.

Ping tests basic network reachability using ICMP packets at the network layer. The HTTP Connectivity Test measures the full HTTP request cycle at the application layer, including DNS resolution, TCP connection, TLS negotiation, server processing, and content download. Ping cannot detect issues with web servers, DNS, or TLS configurations.

No. Your connectivity test requests go directly from your browser to the target URL. We do not proxy, store, log, or process your requests on our servers. All timing measurement and analysis happens client-side in your browser using the Performance API.

Most browsers block fetch requests to localhost (127.0.0.1, localhost) and private network addresses for security reasons (Private Network Access). The tool is designed for testing publicly accessible URLs. For local development testing, use a tool like curl or a dedicated network testing application.

Yes! 100% free with no signup, no account, and no usage limits. Test connectivity for any URL as many times as you need - completely free, forever.