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Developer Tools

Free developer tools that run in your browser. Nothing you enter is stored or sent.

Schedules

Cron Builder & Explainer

Build a cron expression, explain it in plain English, and see the next five run times in UTC.

Time and numbers

Unix Timestamp Converter

Convert seconds or milliseconds since 1970 to dates and back, in UTC and in your own zone.

Files, URLs and tokens

Unix chmod Calculator

Convert between permission checkboxes, octal modes and rwx strings, with the chmod command.

Meta Tag and Open Graph Generator

Write the head tags for a page, with escaping and length checks. Nothing is sent.

Hex Dump and File Inspector

Show a file's bytes in hex and ASCII. The file is read in your browser and never uploaded.

URL Parser and Query Builder

Split a URL into its parts and rebuild query strings with correct encoding.

UUID and ULID Generator

Create random UUIDs and ULIDs, and check an ID's version or timestamp.

JWT Decoder

Decode a token's header and claims. The signature is shown but not verified.

Sitemaps and keys

Sitemap and robots.txt Generator

Write sitemap.xml and robots.txt from a list of URLs, with the protocol limits checked.

Keyboard Key Code Finder

See the key, code and location of any key you press in a box.