Network Tools
Network and web-debugging tools: speed and ping tests, an HTTP request builder, header and status-code explainers, subnet calculators and port lookups. Learn more
CORS Debugger
Test a URL and see whether the browser allows or blocks it.
Download Time Estimator
Estimate download time from a file size and connection speed, with bits and bytes kept straight
Email Header Analyzer
Paste raw email headers to see the delivery hops, SPF/DKIM/DMARC results and basic message fields
HTTP Header Analyzer
Paste response headers or fetch a URL to see what they mean.
HTTP Request Builder
Build and send an HTTP request straight from your browser.
HTTP Response Explainer
Look up any HTTP status code for a plain-English explanation.
Internet Speed Test
Measure your download speed with a file hosted on this site.
IP Subnet/CIDR Calculator
Enter an IPv4 address and CIDR prefix to get the network, broadcast and usable host range instantly
IPv6 Address Compressor/Expander
Paste any valid IPv6 address in any form and get both its fully compressed and fully expanded equivalents
Latency Test
Measure round-trip latency to this site with repeated small requests.
MIME Type / File Extension Reference
Look up a file extension's MIME type
Network HAR Analyzer
Upload a .har file and see a readable breakdown of every request.
Port Number Reference
Look up a network port's usual service
Query String Builder & Parser
Build or parse a URL query string
User-Agent String Builder
Build a custom User-Agent string
WebSocket Inspector
Connect to a WebSocket and watch messages live.
Network and web debugging tools that run in your browser
Is your connection really as fast as you're paying for? The Internet Speed Test times a real download from this site, and the Latency Test measures response time and jitter, the figures that matter for video calls and online gaming. Planning a big download or backup? The Download Time Estimator keeps megabits and megabytes straight so the estimate is right.
For web developers there's a full debugging kit. The HTTP Request Builder sends GET, POST and other requests with your own headers and body. The HTTP Header Analyzer explains each response header and checks for the common security headers. The HTTP Response Explainer turns status codes like 403, 429 and 502 into plain English. The CORS Debugger shows whether the browser will let a page read a cross-site response, and the WebSocket Inspector lets you watch live messages. Export a HAR file from your browser and the HAR Analyzer shows which requests made the page slow.
For networking and email work, the Subnet/CIDR Calculator gives the network, broadcast and usable host range for any IPv4 block. The IPv6 Compressor/Expander converts between short and full addresses, and the Port Number Reference tells you what's likely listening on port 3389 or 5432. The Email Header Analyzer traces a message's route and shows its SPF, DKIM and DMARC results, which helps when checking whether an email is genuine. The Query String Builder, User-Agent Builder and MIME Type Reference round off the set.
Questions and answers
- Why might the Internet Speed Test show a different result from my broadband provider's test?
- Provider tests usually run against a server inside their own network, so they measure the best case. This test downloads a file from EverydayTools' own web host, so the result reflects the whole route from that server to you, plus any Wi-Fi limits on your device. For the fairest comparison, run both on a wired connection and repeat a few times. Then check the Latency Test: a fast download with high jitter can still make video calls choppy.
- What's the difference between the HTTP Request Builder and the CORS Debugger?
- The Request Builder is for working with an API: you choose the method, headers and body and see the full response. The CORS Debugger answers one narrower question, which is why your page can't read a response from another site. It sends the same request twice, once normally and once in "no-cors" mode, so you can tell a CORS block apart from a server or network failure.
- Should I paste headers into the HTTP Header Analyzer or let it fetch the URL?
- Paste them whenever you can. Copy the response headers from your browser's dev tools (Network tab) and you'll get a full analysis, including the security-header check. Fetching only works fully for addresses on this site. For other sites, the browser shows the page just a few basic headers, so the tool tells you it can't judge security headers rather than wrongly reporting them as missing.
- How can the Email Header Analyzer help me spot a phishing email?
- Check the authentication results first. A message that fails SPF, DKIM or DMARC for the domain it claims to be from deserves suspicion. Then read the delivery hops from the bottom up: the first server should belong to the sender's real mail provider, not an unrelated host. The analyzer lays both out clearly, but it can't prove an email is safe, so if in doubt, contact the sender another way.
- Do I need the Subnet/CIDR Calculator if I only use a home network?
- Probably not day to day, since most home routers use a /24 network such as 192.168.1.0/24 and handle addresses for you. It becomes useful when you set up a VPN, a second network for smart devices, or port forwarding. You can see at a glance whether two addresses are on the same network, and the calculator also tells you if an address is private, public or carrier-grade NAT.