56 Free Developer Tools. One Page. Zero Dependencies.

#javascript #productivity #opensource #webdev

I built 56 browser-based developer tools. Every single one is a standalone HTML file — no npm, no build step, no signup, no tracking.

Dev Toolkit →

Why?

I kept switching between 15 different websites for basic tasks — formatting JSON, testing regex, generating hashes, converting colors. Each one had cookie banners, signup walls, or ads covering half the screen.

So I built my own. One tool at a time. All with the same rules:

Single HTML file — view source, it's all there
Runs in your browser — nothing leaves your machine
No dependencies — works offline after first load
Dark theme — because it's 2026

The Full List

Code (18 tools)

Tool	What it does
JSON Format	Beautify, validate, minify, tree view
Regex Test	Live matching, capture groups, 12 presets
Diff Text	Side-by-side line + word diff
Cron Explain	Plain English + next 10 run times
Base64	Encode/decode text and files
Hash Gen	MD5, SHA-1, SHA-256, SHA-512
JWT Builder	Create & decode JWTs
URL Parser	Break URLs into components
UUID Gen	v4 UUIDs, bulk generate
Timestamp	Unix ↔ human time, timezone convert
HTML Escape	Encode/decode HTML entities
Lorem Gen	Lorem ipsum paragraphs, sentences, words
Password Gen	Configurable secure passwords
CSV ↔ JSON	Bidirectional with table preview
YAML ↔ JSON	Docker Compose sample included
TOML ↔ JSON	Cargo.toml, pyproject.toml presets
SQL Format	Beautify + minify SQL queries
Markdown Table	Visual editor → formatted markdown

Design (19 tools)

Tool	What it does
Color Palette	6 harmony schemes, WCAG contrast
Color Convert	HEX ↔ RGB ↔ HSL ↔ HSB ↔ CMYK
Font Pair	20 Google Font pairings
CSS Shadow	Box-shadow generator
CSS Gradient	Linear/radial gradient builder
CSS Flex	Flexbox playground
CSS Grid	Grid layout generator
CSS Animation	Keyframe animator, 12 presets
CSS Filter	blur, contrast, sepia, etc.
Border Radius	8-point control, 10 presets
Box Model	Interactive margin/padding visualizer
Spacing Calc	Design system scale generator
CSS Units	px ↔ rem ↔ em ↔ vw ↔ vh
Aspect Ratio	Calculate and convert ratios
SVG Preview	Paste SVG, see it live
Favicon Gen	Generate favicons from text/emoji
Text Transform	camelCase, snake_case, UPPER, etc.
Image Resize	Resize in browser, keep ratio
Emoji Picker	Search and copy emoji

DevOps (8 tools)

Tool	What it does
chmod Calc	Permission calculator
HTTP Status	All status codes explained
DNS Lookup	A, AAAA, MX, NS, TXT records
SSL Check	Certificate expiry checker
Headers Check	HTTP response headers
IP Info	Your IP, geolocation, ISP
Meta Tags	OG/Twitter meta tag generator
QR Code	Generate QR codes

Writing & Analytics (11 tools)

Tool	What it does
Word Count	Words, chars, reading time
Title Score	Blog title analyzer
README Score	README quality checker
GitHub Stats	Repo analytics dashboard
npm Health	Package health score
LLM Price	Compare AI model pricing
Prompt Price	Calculate prompt costs
Model Picker	Choose the right AI model
AI ROI Calc	AI investment calculator
Dev.to Stats	Article analytics
Markdown Preview	Live markdown renderer