One File Tools

Developer tools, one file each. No build step. No dependencies. No frameworks.

🏷️ Tags:
Aspect Ratio Calculator

Aspect Ratio Calculator

Calculate and simplify aspect ratios instantly. Supports common presets and outputs decimal ratio and CSS padding-bottom values.

Image Tools Easy Live
Box Shadow Generator

Box Shadow Generator

Design CSS box shadows visually with live preview, presets, and copy-ready output.

CSS Tools Easy Live
Clip Path Generator

Clip Path Generator

Visually create complex CSS clip-path shapes and instantly copy the generated code.

CSS Tools Medium Live
Color Palette Extractor

Color Palette Extractor

Extract dominant colors and generate beautiful palettes directly from images in your browser.

Image Tools Medium Live
Command Step Loader

Command Step Loader

Load multiple commands and copy them one at a time with a terminal-style interface.

Developer Utilities Easy Live
Cron Expression Builder

Cron Expression Builder

Build and customize cron schedules with presets, validation, explanations, and upcoming run previews.

Developer Utilities Medium Live
CSS Color Converter

CSS Color Converter

Convert between Hex, RGB, HSL, HSLA, and OKLCH color formats instantly with a visual picker.

Color Tools Easy Live
CSS Grid Generator

CSS Grid Generator

Build CSS Grid layouts visually with configurable columns, rows, gap, and sizing options.

CSS Tools Medium Live
Favicon Generator

Favicon Generator

Generate a complete favicon pack and integration tags from any image, offline.

Developer Utilities Easy Live
Flexbox Playground

Flexbox Playground

Experiment with Flexbox properties visually and copy the generated CSS.

CSS Tools Medium Live
GitHub Token Validator (Terminal)

GitHub Token Validator (Terminal)

Validate GitHub Personal Access Tokens with a terminal-style UI that displays user identity and scopes.

Developer Utilities Easy Live
GitHub Token Validator Plain

GitHub Token Validator Plain

Validate GitHub Personal Access Tokens with a clean, straightforward interface.

Developer Utilities Easy Live
GitHub Token Validator Retro

GitHub Token Validator Retro

Validate GitHub Personal Access Tokens with a retro terminal themed interface.

Developer Utilities Easy Live
Glassmorphism Generator

Glassmorphism Generator

Generate sleek, frosted-glass UI effects for your components.

CSS Tools Easy Live
JSON Diff Viewer

JSON Diff Viewer

Compare two JSON objects semantically with added, removed, and modified value highlighting.

JSON & API Medium Live
JSON Formatter

JSON Formatter

Format, validate, and minify JSON locally in your browser.

JSON & API Easy Live
JWT Decoder

JWT Decoder

Decode and inspect JSON Web Tokens — header, payload, claims, and expiry — entirely in your browser.

JSON & API Easy Live
Meta Tag Generator

Meta Tag Generator

Generate essential HTML meta tags with a live preview and copy-ready code.

Web & SEO Easy Live
Neumorphism Generator

Neumorphism Generator

Create soft, extruded UI elements with customizable neumorphic shadows.

CSS Tools Easy Live
Open Graph Checker

Open Graph Checker

Validate Open Graph tags from any public URL with social previews, health score, and JSON export.

Web & SEO Medium Live
Open Graph Generator

Open Graph Generator

Generate Open Graph meta tags with a live tri-platform preview (Facebook, Twitter, LinkedIn) and copy-ready HTML.

Web & SEO Easy Live
Open Graph Inspector

Open Graph Inspector

Analyze meta tags, social previews, and SEO metadata for any URL with actionable scores.

Web & SEO Medium Live
Palette Generator

Palette Generator

Generate unique, collision-free variation color schemes based on color theory metrics, offline.

Color Tools Medium Live
Password Generator

Password Generator

Generate highly secure, cryptographic random passwords instantly. 100% offline, privacy guaranteed.

Developer Utilities Easy Live
Radii - Border Radius Generator

Radii - Border Radius Generator

Visually create CSS border-radius values with live preview, presets, and copy-ready CSS output.

CSS Tools Easy Live
Robots.txt Generator

Robots.txt Generator

Visually build, manage, and export standard-compliant robots.txt files with live syntax highlighting.

Web & SEO Easy Live
Twitter / X Card Preview

Twitter / X Card Preview

Preview how Twitter/X cards appear with live updates for Summary and Summary Large Image layouts.

Web & SEO Easy Live
UUID Generator

UUID Generator

Generate random v4 UUIDs instantly, offline.

Developer Utilities Easy Live

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One tool.
One file.
Open and use.

A collection of useful developer tools, each built as a single, self-contained HTML file. No build step. No dependencies. No frameworks.

Browse Tools View on GitHub Contribute
28+
Tool Ideas
9
Categories
0 KB
npm install
100%
Browser-based

🌈 Color Tools

🌈

CSS Color Converter

Convert between Hex, RGB, HSL, HSLA, and OKLCH color formats instantly with a visual picker.

🌈

Palette Generator

Generate unique, collision-free variation color schemes based on color theory metrics, offline.

🎨 CSS Tools

🎨

Box Shadow Generator

Design CSS box shadows visually with live preview, presets, and copy-ready output.

🎨

Clip Path Generator

Visually create complex CSS clip-path shapes and instantly copy the generated code.

🎨

CSS Grid Generator

Build CSS Grid layouts visually with configurable columns, rows, gap, and sizing options.

🎨

Flexbox Playground

Experiment with Flexbox properties visually and copy the generated CSS.

🎨

Glassmorphism Generator

Generate sleek, frosted-glass UI effects for your components.

🎨

Neumorphism Generator

Create soft, extruded UI elements with customizable neumorphic shadows.

🎨

Radii - Border Radius Generator

Visually create CSS border-radius values with live preview, presets, and copy-ready CSS output.

🛠️ Developer Utilities

🛠️

Command Step Loader

Load multiple commands and copy them one at a time with a terminal-style interface.

🛠️

Cron Expression Builder

Build and customize cron schedules with presets, validation, explanations, and upcoming run previews.

🛠️

Favicon Generator

Generate a complete favicon pack and integration tags from any image, offline.

🛠️

GitHub Token Validator (Terminal)

Validate GitHub Personal Access Tokens with a terminal-style UI that displays user identity and scopes.

🛠️

GitHub Token Validator Plain

Validate GitHub Personal Access Tokens with a clean, straightforward interface.

🛠️

GitHub Token Validator Retro

Validate GitHub Personal Access Tokens with a retro terminal themed interface.

🛠️

Password Generator

Generate highly secure, cryptographic random passwords instantly. 100% offline, privacy guaranteed.

🛠️

UUID Generator

Generate random v4 UUIDs instantly, offline.

🖼️ Image Tools

🖼️

Aspect Ratio Calculator

Calculate and simplify aspect ratios instantly. Supports common presets and outputs decimal ratio and CSS padding-bottom values.

🖼️

Color Palette Extractor

Extract dominant colors and generate beautiful palettes directly from images in your browser.

🔗 JSON & API

🔗

JSON Diff Viewer

Compare two JSON objects semantically with added, removed, and modified value highlighting.

🔗

JSON Formatter

Format, validate, and minify JSON locally in your browser.

🔗

JWT Decoder

Decode and inspect JSON Web Tokens — header, payload, claims, and expiry — entirely in your browser.

🌐 Web & SEO

🌐

Meta Tag Generator

Generate essential HTML meta tags with a live preview and copy-ready code.

🌐

Open Graph Checker

Validate Open Graph tags from any public URL with social previews, health score, and JSON export.

🌐

Open Graph Generator

Generate Open Graph meta tags with a live tri-platform preview (Facebook, Twitter, LinkedIn) and copy-ready HTML.

🌐

Open Graph Inspector

Analyze meta tags, social previews, and SEO metadata for any URL with actionable scores.

🌐

Robots.txt Generator

Visually build, manage, and export standard-compliant robots.txt files with live syntax highlighting.

🌐

Twitter / X Card Preview

Preview how Twitter/X cards appear with live updates for Summary and Summary Large Image layouts.

One File Tools

Try a tool right here. Every tool is a single HTML file you can download and use anywhere.

json-formatter.html 
Formatted output will appear here...
🎓 Part of Social Summer of Code — Easy: 20 pts · Medium: 30 pts · Leaderboard
♿

Accessibility

Contrast checkers, heading structure, ARIA references

0 tools
🌐

Browser & Network

User agents, viewport info, cookies, and headers

0 tools
🌈

Color Tools

Pickers, contrast checkers, palettes, and converters

2 tools
🎨

CSS Tools

Shadows, grids, flexbox, gradients, and generators

7 tools
🛠️

Developer Utilities

UUIDs, hashes, regex, cron, passwords, and QR codes

8 tools
🖼️

Image Tools

Dimensions, converters, SVG, favicons, and metadata

2 tools
🔗

JSON & API

Formatters, JWT decoders, URL encoders, and curl builders

3 tools
📝

Text & Content

Counters, converters, diffs, and Markdown preview

0 tools
🌐

Web & SEO

Meta tags, OG previews, sitemaps, and SEO utilities

6 tools 
  ___  _  _ ___   ___ ___ _    ___   _____ ___   ___  _    ___
 / _ \| \| | __| | __|_ _| |  | __| |_   _/ _ \ / _ \| |  / __|
| (_) | .` | _|  | _| | || |__| _|    | || (_) | (_) | |__\__ \
 \___/|_|\_|___| |_| |___|____|___|   |_| \___/ \___/|____|___/
~/one-file-tools $

One File Tools

Developer tools, one file each. Zero dependencies.

$ open tools/json-formatter.html

$ # That's it. No npm. No build. No server.
// Color Tools
  • css-color-converter Convert between Hex, RGB, HSL, HSLA, and OKLCH color formats instantly with a visual picker. EASY
  • palette-generator Generate unique, collision-free variation color schemes based on color theory metrics, offline. MED
// CSS Tools
  • box-shadow-generator Design CSS box shadows visually with live preview, presets, and copy-ready output. EASY
  • clip-path-generator Visually create complex CSS clip-path shapes and instantly copy the generated code. MED
  • css-grid-generator Build CSS Grid layouts visually with configurable columns, rows, gap, and sizing options. MED
  • flexbox-playground Experiment with Flexbox properties visually and copy the generated CSS. MED
  • glassmorphism-generator Generate sleek, frosted-glass UI effects for your components. EASY
  • neumorphism-generator Create soft, extruded UI elements with customizable neumorphic shadows. EASY
  • border-radius-generator Visually create CSS border-radius values with live preview, presets, and copy-ready CSS output. EASY
// Developer Utilities
  • command-step-loader Load multiple commands and copy them one at a time with a terminal-style interface. EASY
  • cron-expression-builder Build and customize cron schedules with presets, validation, explanations, and upcoming run previews. MED
  • favicon-generator Generate a complete favicon pack and integration tags from any image, offline. EASY
  • github-token-validator-terminal Validate GitHub Personal Access Tokens with a terminal-style UI that displays user identity and scopes. EASY
  • github-token-validator-plain Validate GitHub Personal Access Tokens with a clean, straightforward interface. EASY
  • github-token-validator-retro Validate GitHub Personal Access Tokens with a retro terminal themed interface. EASY
  • password-generator Generate highly secure, cryptographic random passwords instantly. 100% offline, privacy guaranteed. EASY
  • uuid-generator Generate random v4 UUIDs instantly, offline. EASY
// Image Tools
  • aspect-ratio-calculator Calculate and simplify aspect ratios instantly. Supports common presets and outputs decimal ratio and CSS padding-bottom values. EASY
  • color-palette-extractor Extract dominant colors and generate beautiful palettes directly from images in your browser. MED
// JSON & API
  • json-diff-viewer Compare two JSON objects semantically with added, removed, and modified value highlighting. MED
  • json-formatter Format, validate, and minify JSON locally in your browser. EASY
  • jwt-decoder Decode and inspect JSON Web Tokens — header, payload, claims, and expiry — entirely in your browser. EASY
// Web & SEO
  • meta-tag-generator Generate essential HTML meta tags with a live preview and copy-ready code. EASY
  • open-graph-checker Validate Open Graph tags from any public URL with social previews, health score, and JSON export. MED
  • open-graph-generator Generate Open Graph meta tags with a live tri-platform preview (Facebook, Twitter, LinkedIn) and copy-ready HTML. EASY
  • open-graph-inspector Analyze meta tags, social previews, and SEO metadata for any URL with actionable scores. MED
  • robots-txt-generator Visually build, manage, and export standard-compliant robots.txt files with live syntax highlighting. EASY
  • twitter-x-card-preview Preview how Twitter/X cards appear with live updates for Summary and Summary Large Image layouts. EASY
// Links

One File Tools

Developer tools, one file each. No build step. No dependencies. No frameworks.

28+
Tool Ideas
9
Categories
28
Live Tools
0
Dependencies
💡

Philosophy

One file. Each tool is a single .html file.
Zero build. No npm install, no bundler, no server.
Browser only. Runs entirely client-side.
Open source. Unlicense. Do what you want.

Start Contributing

Pick a tool, build it in a single HTML file, and submit a PR.

GitHub Contributing Guide
♿

Accessibility

    🌐

    Browser & Network

      🌈

      Color Tools

      • CSS Color Converter
      • Palette Generator
      🎨

      CSS Tools

      • Box Shadow Generator
      • Clip Path Generator
      • CSS Grid Generator
      • Flexbox Playground
      🎓

      SSoC (Social Summer of Code)

      This project is part of Social Summer of Code. Pick an Easy (20 pts) or Medium (30 pts) issue, build a tool, and earn contribution points. Learn more · Leaderboard