Free online developer tools

Auto-detects pasted strings such as JWT, JSON, base64, URI, timestamp or gzip and shows the decoded view.

Explains a cron expression in plain words, field by field, and lists the next ten run times.

Moves the CSS you paste into inline style attributes on the HTML, the format email clients expect.

Converts CSS pixel values to rem and back.

Rewrites the variables of a .env file as entries for a netlify.toml configuration.

Opens an HTTP Archive file so you can inspect recorded requests and timings.

Previews pasted HTML in a sandbox, can run scripts, copy as PNG and make a share link.

Indents and structures raw JSON for reading and validation.

Validates JSON Lines files, such as AI datasets and event logs, and jumps to the failing line.

Decodes PHP serialize() strings, such as WordPress options or transients, into a readable nested dump.

Turns a URL query string into a JSON object.

Tests a regular expression with flags against sample text, shows match counts and supports replace.

Generates random UUIDs.

Generates random UUID v4 values with options for hyphens and uppercase.

Tries JSONata query and transformation expressions against sample JSON.

Compiles modern JavaScript with Babel presets and plugins in the browser and shows the output.

Converts CSS declarations into a JavaScript style object for CSS-in-JS libraries.

Maps plain CSS rules onto equivalent Tailwind utility classes.

Converts a style object into a CSS template literal for styled-components.

Runs ESLint rules on pasted JavaScript with custom config and shows the reported problems.

Translates Flow type annotations into TypeScript.

Generates Java classes from a GraphQL schema.

Parses a GraphQL schema and shows its abstract syntax tree.

Generates TypeScript types from a GraphQL schema.