Tools / Regex

• Softwium - Regular Expression Visualizer.

Bookmarklets

• Make Bookmarklets - Online tool to turn JavaScript into a bookmarklet.

Tools / Debugging & Development

• endpoints.dev - View realtime HTTP requests using a endpoints.dev generated URL.

• Hoppscotch - A lightweight, web-based API development suite.

• JavaScript Visualizer 9000 - Loupe-inspired JavaScript execution visualizer

• JSONPlaceholder - Free fake API for testing and prototyping.

• RecipeUI - Open source Postman alternative with type safety built in.

Tools / Deobfuscation & Transformation

• Compiler Explorer - Run compilers interactively from your web browser and interact with the assembly

• Markdown to HTML - Paste or type your markdown and see it rendered as HTML. Download or copy the resulting HTML.

• Markdown Tools - Tools to convert Markdown to/from a number of formats. E.g. Html to Markdown, or a CSV to a Markdown table.

• SWC - compile JS/TS files using modern JS features and outputs valid code that is supported by all major browsers.

Tools / Diagramming & Scratch

• asciiflow - ASCIIFlow is a client-side only web based application for drawing ASCII diagrams.

• dbdiagram - Draw Entity-Relationship Diagrams, Painlessly.

• dot-to-ascii - Graphviz to ASCII converter using Graph::Easy.

• Excalidraw - Virtual whiteboard.

• JSON-to-Chart - Create beautiful charts from JSON data in your browser.

• nomnoml - A tool for drawing UML diagrams based on a simple syntax.

• Sequence Diagram - An online tool / software for creating UML sequence diagrams.

Tools / Generators

• JSONGenerator - Create random JSON data

• Readme - All in one tool to quickly generate a readme for your project or github profile.

Tools / Image

• JPEG.rocks - Privacy-aware JPEG optimizer

• PicPerf - Boost web performance with image optimization. Analyze and improve <img> tags, <style> tags, and inline CSS.

• PNG-to-SVG - Free conversion from JPG or PNG images To vectorized SVG.

• SVG-to-backgroundImage - Convert your SVG files into CSS url (data URIs) by encoding it.

Tools / Performance

• Perflink - JS benchmarks

Tools / Playgrounds

• JSONCrack - Visualize CSV/JSON/TOML/XML/YAML instantly into graphs.

• Markmap - Visualize markdown as a feature-rich mindmaps.

Tools / Regex

• Regulex - JavaScript Regular Expression Visualizer.

Tools / Scripting & Copy/Paste

• crontab guru - The quick and simple editor for cron schedule expressions by Cronitor

• CSS Scan - Box Shadows - CSS, Ready to use, click to copy

• CSS Scan - Buttons - CSS, Ready to use, click to copy

• CSS Scan - Checkboxes - CSS, Ready to use, click to copy

• CSS Scan - Shapes - CSS, Ready to use, click to copy

• Devtools Tips - Copy-and-paste'able collection of useful cross-browser DevTools snippets.

Tools / Transformation

• Babel REPL - The compiler for next generation JavaScript

Tools / Presentation

• snapify - Snappify enables you to create stunning presentations, with first-class support for code snippets.

Resources / Cheat Sheets

• OWASP Cheat Sheet Series - A concise collection of high value information on specific application security topics.

Resources / Documentation

• ECMAScript Proposal Stages

Resources / Glyphs & Icons

• Icônes - Over 150,000 open source vector icons.

Resources / Validation & Parsers

• Ada URL Parser - WHATWG-compliant and fast URL parser written in modern C++, online.

Security / Test

• HSTS Preload - Check HSTS preload status and elibility.

• Mozilla Observatory - A set of tools to analyze your website and inform you if you are utilizing the many available methods to secure it.

• Security Headers by Probely - An easy to use tool designed to help you better deploy and understand modern security features that are available for your website.

• Web Check - All-in-one OSINT tool for analysing any website.

Resources / Validation & Parsers

• CSP Evaluator - Evaluate CSP rules

Resources / Documentation

• ExplainShell - A better way to read MAN pages.

Tools / Deobfuscation & Transformation

• JSON ABC - Sorts JSON alphabetically

Resources / Glyphs & Icons

• Tabler Icons

Tools / Debugging & Development

• Reqbin - REST & SOAP API Online Testing Tool

Bookmarklets

• artoo.js - Client-side scraping utility for the currently loaded uri.

• CSS Stress Test (⭐872) - JavaScript to test each CSS class on a page and report which are hindering performance.

• deCSS3 (⭐312) - A lil' bookmarklet that will strip out your CSS3 rules and show you how gracefully you're degrading.

• DOM Monster - A cross-platform, cross-browser bookmarklet that will analyze the DOM & other features of the page you're on.

• Ramda (⭐23k) - Add Ramda to any page!

• Rulers Guides - A JavaScript library which enables Photoshop-like rulers and guides interface on a web page.

• Viewport Resizer - A browser-based tool to test any website's responsiveness.

Tools / Debugging & Development

• Babel Time Travel - Travel in time as babel transpiles.

• Beeceptor - Rule based API mocking service. When rules are matched, a request is mocked, else target endpoint is hit as usual. Create custom endpoints to test and debug rest APIs.

• DebugJS - Debug your JavaScript in the browser (lol?)

• Hook.io - Instantly deploy microservices in over 11+ languages (OSS!)

• httpbin - HTTP Request & Response service.

• jsonbin - Custom, mock JSON API

• Loupe - Similar in goal to SlowmoJS, a JavaScript call stack visualizer.

• Mockbin - Generate custom endpoints to test, mock, and track HTTP requests.

• SlowmoJS - Execute JavaScript in slow motion.

Tools / Deobfuscation & Transformation

• AST Explorer - Parse JS to an explorable AST tree via acorn, babel, babylon, espree, esprima, recast, shift, and typescript.

• fixmyjs - Automatically fix your JS, driven by JSHint.

• JSNice - Statistical renaming, type inference and deobfuscation.

Tools / Diffing

• JSONDiffPatch - Run a visual or non-visual diff on two JSON blobs.

Tools / File Sharing

• file.io - Ephemeral file sharing. Convenient, anonymous and secure.

• instant.io - Instant file transfer/sharing over WebTorrent

Tools / Generators

• Pure CSS Apple - Pure CSS Apple devices with scrollable media

Tools / Image

• Favic-o-matic - Literally generates every favicon neccessary + markup.

• Squoosh - Compress and optimize images in browser

• SVGOMG - Try SVGO (⭐20k) (SVG Optimizer) in the browser!

Tools / Playgrounds

• codepen - Social development environment for front-end designers and developers. Build and deploy a website, show off your work, build test cases to learn and debug, and find inspiration.

• CodeSandbox - Online code editor and sandbox

• Ellie - The Elm Live Editor

• ES.nextBin - Like RequireBin but ES2015

• JSBin - JS/Coffee/Babel/Babel/Live/JSX/HTML/Markdown/Pug/CSS/Stylus/LESS/Sass

• JSFiddle - JS/ES3/Coffee/HTML/CSS/Sass

• playcode.io - JS/Typescript/Coffee/LiveScript/Babel/CSS/Sass/LESS/Stylus/HTML/Pug

Tools / Regex

• Debuggex - PCRE/Python/JavaScript regex matching.

• ExtendsClass - PHP/Python/Ruby/JavaScript regex matching.

• reFiddle - Ruby/.NET/JavaScript regex matching.

• RegExplained - JavaScript regex matching.

• Regexr - JavaScript regex matching.

Tools / Transformation

• Sassmeister - Sass/Scss <-> CSS

• Terser - JavaScript parser, mangler and compressor toolkit for ES6+

• WebAssembly Explorer - translate C/C++ to WebAssembly, and then see the machine code generated by the browser.

Resources / Browser Information

• What's My Browser?

Resources / Compatability

• HTML5

Resources / CSS Inliners

• Campaign Monitor

• MailChimp

Resources / CSS Post Processors

• Pleeease

Resources / Documentation

• DevDocs - Basically Dash but a web application and FREE.

Resources / Easings & Animations

• Ceaser

Resources / Glyphs & Icons

• Copy/Paste Character

• Entity Lookup

• Icon Finder

• Icon Monstr

Resources / Open JSON & Feeds

• FillText - Generate JSON datasets for testing or demonstration purposes

• Zippopotamus - Zipcode to Geo

Resources / Proxy as a Service

• CORS Anywhere - Proxies any HTTP request through a CORS enabled environment.

Resources / Responsiveness

• Responsive Patterns

Resources / Validation & Parsers

• numverify - Validate phone numbers from over 200 countries.

Security / SSL

• GetHTTPSForFree! - Genuinely FREE SSL certificates (courtesy of Let's Encrypt)

• Self-Signed Certificate Generator - A self-signed certificate generator.

The Outside World / Swag

• DevStickers

• DevSwag

• StickerMule