Developer tools
33 tools, all running in your browser
The five-second jobs that interrupt everything else: reading a token, reshaping a payload, checking an id. All of them run in this tab, which is worth knowing when the thing you are pasting came out of production.
Format and inspect
Make a payload readable, and find out what is wrong with it.
- JSON formatterPretty-print, minify, sort keys, and find the line your JSON breaks on.
- Regex testerWatch a pattern match your text as you type, with every capture group listed.
- SQL formatterTurn a wall of SQL into something you can read, in your own dialect.
- Cron expression explainerRead a cron schedule as a sentence and see when it next runs.
- XML formatterPretty print XML so you can read it, or minify it back to a single line.
- UUID validatorFind out whether an identifier is a real UUID, and which version made it.
- Cron expression generatorPick how often a job runs and get the cron expression for it, read back in words.
- YAML validatorCheck a YAML file, see the line that breaks it, and catch the values that mislead.
- HTML formatterIndent minified or messy HTML and the CSS and JavaScript inside it.
- JavaScript minifierCompress JavaScript or TypeScript with terser and see what it saves, raw and gzipped.
- HTML minifierShrink a page and the CSS and JavaScript inside it, and see what it saves.
- Regex explainerRead a regular expression piece by piece, in plain English.
Convert between formats
Move data from the shape one system produces into the shape the next one wants.
- JSON to CSVTurn an API response into something a spreadsheet will open.
- Colour converterHEX to RGB to HSL, with the contrast figures you need to use it.
- Timestamp converterTurn epoch time into a date you can read, and back again.
- YAML to JSONTurn a YAML config into JSON, and find the line that will not parse.
Encode and decode
Wrap a value up for transport, or unwrap one you have been handed.
- Base64 encoderConvert text to Base64 and back, with URL-safe output and proper Unicode support.
- JWT decoderRead what is inside a token and check its signature against a key or a JWKS, all in your browser.
- JWT generatorBuild a signed JSON Web Token for testing, without sending your secret anywhere.
- URL encoderPercent-encode a query value, or read back a URL someone escaped twice.
- JSON escapeTurn text into a safe JSON string value, or read an escaped one back.
- URL parserSplit a URL into host, path, and decoded query, and strip its tracking tags.
Why a local tool is the right default here#
Developer utilities get fed the most sensitive material on the site. A JWT is a live credential, a JSON payload is often a real customer record, and a CSV export is frequently the contents of a table someone is under a legal obligation not to hand to a third party. From the outside, a tool that handles all of that carefully looks exactly like one that does not. The only real difference is whether anything leaves the page.
Nothing here does. Every tool in this category is JavaScript running in your browser, and no request carries your input, which you can verify in thirty seconds by opening the network panel and pasting something in. It also explains the absence of a sign-up, a quota, and a session that expires: there is no server keeping track of you to enforce any of them.
The usual objection is that a browser cannot do the heavy work, and for this class of tool that stopped being true some time ago. Hashing goes through the Web Crypto API, which is the same set of primitives a server would call. Parsing a megabyte of JSON takes a few milliseconds. Your machine sets the ceiling, and none of these jobs comes close to it.
Picking the right one#
For data that arrives in the wrong shape, start with the JSON formatter when a payload will not parse and you need the line number. The converters move data between JSON, CSV, XML, YAML, and Excel in both directions, so a spreadsheet can become an API body and a response can open in Excel. When the JSON has to become code, JSON to TypeScript and its neighbours write the matching types for TypeScript, C#, or Go, or a Zod schema.
For values that arrive encoded, the decoders do the unwrapping. Base64 and URL encoding cover most of what shows up in a query string or a header, and the JWT decoder goes further: it resolves the expiry claims to real dates and will check the signature if you give it the key.
For values you need to read, the timestamp converter turns epoch time into a date and back, the colour converter moves between hex, RGB, HSL, and HSV with the contrast ratios worked out, and the cron explainer reads a schedule as a sentence. Making a new value is a job for the generators: the UUID generator writes version 4, 5, or 7, and the hash generator digests a string or a file.
Frequently asked questions#
Is anything I paste sent to a server?
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No. There is no server to send it to: these pages are static files and every tool is JavaScript in your tab. Open your browser's network panel, paste something in, and you will see no request go out. That check is worth doing on any tool that asks for data you care about, this one included.
Can I use these on data I am not allowed to upload?
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That is the case they are built for. Since the data never leaves your browser, using one of these is closer to opening a text editor than to using a web service. The one thing to be careful with is a shared or managed machine, where a browser extension or a corporate policy may be watching the page even though the page itself is not.
Why is there no sign-up?
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Because there is nothing to sign up to. No account, no quota, and no stored history, since none of these tools has a back end that could hold any of it. Bookmark the page and it will behave the same way in a year.
Do these work offline?
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Yes, once a page has loaded. Nothing after that point touches the network, so you can pull the plug and carry on working. Only a fresh page load needs a connection.