DevToolbox — Free Browser Developer Tools

DevToolbox is a single, fast, ad-light toolbox for the small text and data jobs that come up constantly while coding, configuring servers, or writing documentation. Instead of opening five different websites and pasting your data into each one, you keep everything in one tab that works offline and never sends your input anywhere. Every utility here is built for one narrow task and does it immediately.

The collection is organised around the work developers actually repeat: converting between JSON, YAML, XML, TOML and CSV; formatting and diffing code and prose; generating hashes, UUIDs, slugs and passwords; reading timestamps and timezones; and moving numbers between binary, octal, decimal and hexadecimal. There is no wizard, no sign-up wall, and no "pro" tier hiding the feature you need behind a paywall.

Because each tool runs entirely in your browser using standard web APIs, it starts instantly, keeps working without a network connection, and leaves your data on your own machine. The underlying algorithms follow stable public specifications, so the results stay correct year after year without the site needing constant maintenance. Pick what you need from the categories above, or jump straight to a single-purpose tool from the quick links.

Privacy is a design constraint here, not a footnote. Converting a configuration file or hashing a token often means handling something you would not paste into a random website, so DevToolbox was built so that sensitive input simply cannot leave the page. There is no account to create, no upload endpoint to leak to, and no tracking that follows you across the web. What you process stays in your browser tab until you close it. That is also why every tool behaves identically whether you are online or offline, and why there is nothing to sign in to before you can begin.