Fiddler is a Web Debugging Proxy which logs all HTTP(S) traffic between your computer and the Internet. Fiddler allows you to inspect all HTTP(S) traffic, set breakpoints, and "fiddle" with incoming or outgoing data.

Charles is an HTTP proxy / HTTP monitor / Reverse Proxy that enables a developer to view all of the HTTP and SSL / HTTPS traffic between their machine and the Internet. This includes requests, responses and the HTTP headers (which contain the cookies and caching information).

The easy way to track your Core Web Vitals and boost website performance. Real-user monitoring with automatic noise-cancelling and actionable recommendations.

Quickly view basic info about every webpage, including server location, IP addresses, certificate expiration date and issuer, HTTP status code and load time.

PCAPdroid is an android app to capture the phone traffic and analyze it remotely (e.g. via Wireshark). The traffic can be easily downloaded from a remote device thanks to the integrated HTTP server, or streamed to a remote UDP receiver.

HTTP Debugger Pro - A Professional HTTP Sniffer and Analyzer for Developers.

NodePing Server Monitoring and Web Site Monitoring. Simple but powerful Internet service monitoring. Checks as frequent as once a minute.

HttpFox monitors and analyzes all incoming and outgoing HTTP traffic between the browser and the web servers.

Working quietly on the Menubar, Surge is a high-performance HTTP/SOCKS5 proxy server. It is capable of intercepting and logging the summary of HTTP traffic, and meanwhile transmitting the traffic to other proxy servers according to the flexible rule system.

HTTP Headers allows you to quickly see the HTTP header information for the current URL.

Log all traffic on your network card. Analyze and parse network packets. Capture transmitted files and passwords.

Driftnet is a program which listens to network traffic and picks out images from TCP streams it observes.

HTTP Analyzer is such a handy tool that allows you to monitor, trace, debug and analyze HTTP/HTTPS traffic in real-time. It is used by industry-leading companies including Microsoft, Cisco, AOL and Google.

NetStat Agent is a powerful and easy-to-use network toolkit for monitoring and diagnosing. It includes all useful network tools like netstat, ping, traceroute, ipconfig, dns query (nslookup), whois, arp, route and http checker.

updown.io is a HTTP monitoring solution with a clean UI and a cheap and simple pricing. It notifies you of downtimes by email or SMS and provides a public status page you can share.