The second tab you
always have open.
38 browser tools for building and shipping websites — encoders, formatters, header inspectors, waterfalls, security checks. No install, no account for most of it. Each page explains what the tool does, when it actually helps, and which ones are worth handing to a schedule.
By where it fits in the work
- 6 Debug HTTP Find out what the server actually sent back.
- 4 Optimize Find out what the page really costs.
- 6 Secure Headers, policies and the CMS you inherited.
- 3 Ship Check what the rest of the world sees.
- 11 Convert Move data between the encodings the web insists on.
- 8 Build Get the expression, the colour or the schedule right first time.
After it ships
Everything above answers a question about right now. These are about the questions that arrive later — did it change, does the journey still work, and what is it like for people who are not you.
- Scheduled Checks for People Who Ship Nothing you build stays checked. The interesting result is never the first one — it is the one that differs from last week. Read →
- Testing the Journey, Not the Page You ship journeys and you monitor pages. The gap between those two is where the expensive bugs live. Read →
- What Your Users Actually Experience You are the least representative visitor your site has: local, cached, on fibre, on a fast machine. Field data is everyone else. Read →
Handbook
Practices rather than tools — what to check before a launch, how to work out whose bug it is, and which security work is cheap now and expensive later.
- The Checks Worth Running Before a Launch Most launch disasters are not dramatic. They are a robots file that came from staging and a share card that renders as a bare link.
- Is It My Code, the API, or the Browser? The console message usually names a rule, not a cause. Three checks in the right order tell you whose problem it actually is.
- Core Web Vitals Without the Score Obsession A hundred in the lab and a failing field assessment is a normal, consistent outcome — not a contradiction to be reconciled.
- Which Security Headers Are Worth the Risk Three of them are safe to ship this afternoon. One of them will break your analytics, and it is also the one that matters most.
Every tool here is live on NetTests.NET
This site explains the tools; NetTests.NET runs them against your own sites, and will keep running the useful ones on a schedule so you find out when something changes rather than when someone reports it.