Free Developer Tools

Build a regular expression and see it match live against your own test text, with a plain-English breakdown of what each part does.

Browser support tables for HTML, CSS, and JavaScript features. Shows which versions ship a feature and what share of users that covers.

Paste a shell command and it highlights each flag and argument individually, pulling the explanation straight from the man page.

A library of CSS animations you configure in the browser. Pick the effect, tune the timing, and copy the keyframes.

A visual editor for CSS box shadows, including layered ones, with the rule written out as you drag.

Shows how much an npm package adds to your JavaScript bundle and how long it takes to download, before you install it.

Paste in code and it renders a styled, syntax-highlighted image of it, for sharing snippets that look good in a tweet or a slide.

A set of code formatters, minifiers, and converters (JSON, XML, Base64, and more) for cleaning up or transforming code in the browser.

A visual gradient editor that outputs the CSS. Handles linear and radial, multiple stops, and shows a fallback colour.

Paste messy JSON and get it indented and readable. Validates as it goes and points at the line that breaks.

Paste a JSON Web Token to decode its header and payload and check its signature. Also lists JWT libraries by language.

A quick tour of a programming language on one page, written as commented code. Covers dozens of languages and tools.

A Python tool from Microsoft that converts PDF, Word, Excel, PowerPoint, images, and audio into Markdown for feeding to a language model.

NASA's free, open-source 3D globe engine for developers. Build your own map or Earth viewer on it, or try the live web examples.

Generates the two-shadow CSS that produces the soft extruded look. Drag the sliders and copy the rule.

A collection of cheat sheets for programming languages and frameworks, one page per language.

A full workspace for building and testing APIs: send requests, save collections, write tests and share them with a team. Free plan, account required.

Same idea as Carbon, turning pasted code into a shareable image, but with a different set of gradient themes. Made by Raycast.

Build and test regular expressions with live highlighting, a cheat sheet and saved community patterns. Supports JavaScript and PCRE.

Sends HTTP requests from the browser to test an API, with no install. Shows the response and can turn the request into code.

Step-by-step learning roadmaps for developer roles and skills, such as frontend, backend and DevOps, built and kept up by the community.

Self-hosted project management with Kanban boards, sprints, task dependencies, and time tracking. Runs as a Docker stack with PostgreSQL on your own server, syncs issues from GitHub and GitLab, and ships an MCP server so Claude can read projects and create tasks. Source-available rather than OSI open source.