Free developer tools that run in your browser
Small, fast tools for the jobs developers do every week: tidying and checking JSON, reading a cron schedule, converting a Unix timestamp and working out file permissions.
Runs entirely in your browser. Nothing you paste is sent to our server, stored or logged.
JSON Formatter and Validator New
Pretty print, minify and validate JSON, with the exact line of any error and how to fix it.
Open the json formatter →Cron Expression Generator New
Write a cron schedule, read it in plain English and see when it runs next.
Open the cron generator →Unix Timestamp Converter New
Turn Unix timestamps into readable dates and back, in seconds or milliseconds.
Open the timestamp converter →Chmod Calculator New
Convert Linux file permissions between numbers and letters, and see who can do what.
Open the chmod calculator →Why everything here runs in your browser
Developers paste sensitive things into online tools all the time: access tokens, production timestamps, config files, customer data. Every tool in this section does its work with JavaScript on your own machine. Nothing you enter is sent to our server, logged or stored, and the site tells your browser to block its scripts from sending data anywhere else.
Explained, not just converted
Each tool shows its reasoning. The cron generator spells a schedule out in plain English and lists when it will actually run, the chmod calculator says who can do what, and the timestamp converter shows the same moment in several formats so you can see which one your system expects.
Links you can share safely
Where a tool gives you a link to share, the value goes after the # in the address. Browsers never send that part to a server, so the person you send it to sees the same result without the value passing through ours.