About DevToolBench

A workbench of developer tools that never leave your browser.

Why this workbench exists

Pretty-printing a minified API response, generating an identifier for a fixture, working out what the fourth field of a cron line actually means: these are the ten-second detours of a normal working day. The arithmetic behind them was settled decades ago. What makes them annoying is everything wrapped around the answer.

Search for one of these utilities and the first result is usually a page carrying six advert slots, a cookie wall, a newsletter modal and a text area that stutters once the payload passes a megabyte. A fair number of those pages ship your input to a backend to perform work that the browser could finish in a millisecond. If the payload happens to contain a customer record or an internal hostname, it has just been written to somebody else’s access log.

DevToolBench is the reaction to that. One page, one job, and the smallest interface the job needs. The catalogue is organised into a few plain groups:

• Formatters — Clean up and validate structured data.
• Generators — Create identifiers and test data.
• Text tools — Measure and rework written content.

The work happens on your machine

Each tool ships as JavaScript inside the page it lives on. It reads the text in the input box from your own tab’s memory, computes, and paints the result — no request crosses the network while you use it. That is a practical distinction rather than a philosophical one. It means a response body copied straight out of production, a staging hostname or a real customer identifier can go into the box without leaving your laptop.

It also means the page keeps working when the connection does not. Load a tool once, disconnect, and it behaves exactly the same on a train as it does at a desk.

What this site deliberately leaves out

There is no account, no free tier with a quota above it, and no saved history. Nothing you type into a tool is written to a database, because the tools carry no server-side code whatsoever — they are static files that execute in your tab. Close it and the input is gone, including from us, who never had it.

One exception is worth naming plainly, or the sentence above becomes a slogan instead of a fact. The two forms further down this page post to a small endpoint on this domain, which turns what you wrote into an email to the maintainer. That endpoint is the entire server-side surface of DevToolBench, it runs only when you press send, and the privacy page lists field by field what reaches it.

Who builds it

DevToolBench is built and maintained by Revin, a software consultancy that designs, builds and maintains products for its clients, a number of them based in the United Kingdom. These tools are the ones we kept rewriting for ourselves, tidied up and put somewhere public.

How the tools are kept honest

The logic of every tool lives in a plain module with unit tests next to it, separate from the interface that renders it. Those tests are then attacked by mutation testing: the pipeline deliberately damages the code — flips a comparison, deletes a filter, forces a branch — and requires that some test notice and fail. A suite that merely proves a function does not throw never clears that bar, so it does not count as coverage here. The explanatory text on each page is written and edited by a person who has used the tool in anger.

Reporting something broken

Wrong output, a confusing label, a layout that collapses on your phone — all of it is worth reporting, and the bug form exists for exactly that. Opening it from a tool page carries the tool across, so the only things left to write are what you did, what you expected and what turned up instead. An email address is optional; without one there is simply no way for anyone to write back to you.

The other half of that door is the suggestion form. Most of what sits on this workbench began as somebody describing a chore they were still doing by hand, so if you came here looking for something and left without it, saying which tool was missing is the single most useful thing you can do.

Elsewhere

OnPageKit is our companion hub, built on the same rules and pointed at on-page seo tools instead.