Developer Tools
Formatters, converters, generators and validators for developers.
- JSON Formatter & ValidatorBeautify, minify and validate JSON with precise error positions.
- Base64 Encoder & DecoderEncode or decode Base64 text, files and data URLs, with UTF-8 support.
- Cron Expression GeneratorBuild, explain and preview cron schedules in plain English.
- Password GeneratorGenerate strong random passwords and passphrases with an entropy readout.
- Regex TesterTest regular expressions live with match highlighting and capture groups.
- Unix Timestamp ConverterConvert Unix epoch seconds or milliseconds to a human date, and back.
- Chmod CalculatorTick permission boxes to get the octal chmod value, or type a value to see what it grants.
- JSON to CSV ConverterConvert JSON arrays to CSV and CSV back to JSON, with nested key flattening.
- JWT DecoderDecode a JWT header and payload, and check its expiry — offline.
- Subnet CalculatorEnter an address and prefix to get the network, broadcast, usable range and host count.
- UUID GeneratorGenerate cryptographically random UUID v4, time-ordered v7 and Nano IDs.
- Hash GeneratorGenerate SHA-256, SHA-384, SHA-512, SHA-1 and MD5 hashes of text or files.
- Text to BinarySee any text as binary, hexadecimal, decimal, octal and UTF-8 bytes at once.
- URL Encoder & DecoderPercent-encode or decode URLs and query strings, with a parameter breakdown.
More detailsWhat these tools have in common · Choosing between similar tools · A note on what these tools will not do
What these tools have in common
Every tool here runs as plain JavaScript inside your browser. That matters more for developer tools than for most software, because the things you paste into them are rarely harmless: production API responses, JWTs from a staging environment, config files with connection strings, log excerpts containing customer data. None of it is transmitted, because there is no server to transmit it to. You can load any of these pages, disconnect from the network, and keep working.
Choosing between similar tools
| If you need to | Use |
|---|---|
| Read a minified API response | JSON formatter — it also reports the line and column of a syntax error |
| Compare two config files or responses | Diff checker, ideally after sorting keys in the JSON formatter first |
| See what is inside a token | JWT decoder — it decodes only, and deliberately never asks for your signing key |
| Verify a downloaded file | Hash generator — SHA-256 in the browser, no upload |
| Work out a cron schedule | Cron generator for a custom one, or the schedule library for a ready-made expression |
| Debug a regular expression | Regex tester with live match highlighting and capture groups |
A note on what these tools will not do
Some things genuinely cannot be done well in a browser, and we would rather say so than ship something that half works. The JWT decoder does not verify signatures, because that would mean asking you to paste a secret into a web page. There is no HEIC converter, because Chrome and Firefox cannot decode HEIC and the alternatives are either uploading your photo or shipping a megabyte of WebAssembly. Where a tool is missing, the reference pages usually explain the platform-native way to do it instead.
Developer reference
- HTTP status codesEvery status code, what triggers it and how to fix it.
- Cron schedule examplesReady-made cron expressions for every common schedule.
- Port number referenceWhat runs on each port and how to check what is listening.
- CSS unit converterspx, rem, em, pt and more, with an adjustable root font size.
- Data size convertersBytes, KB, MB, GB, TB and their binary counterparts.