{ DevTools }

431 free browser-based developer tools by Jlvextension — split HTML, minify CSS, format JSON, generate UUIDs and more. No installs, no sign-ups.

431 tools | Live 417 · Beta 1 · Planned 13
// tool of the week
JSON Lines Formatter

Beautify newline-delimited JSON for easier reading and troubleshooting.

NEW
JSON Formatter Developer
Open tool →
// recently updated
🎨
CSS Fluid Typography Calculator
Build responsive typography scales
NEW
📋
Mermaid Diagram Editor
Mermaid Diagram Editor — free browser-based tool
NEW
🎨
CSS Z-Index Visualizer
Understand CSS stacking order
NEW
💻
Inline CSS for Email
Inline CSS into email HTML
NEW
// explore by type
🎨 CSS 41 tools 📄 HTML 52 tools ⚡ JavaScript 58 tools 🔐 Encoding & Security 41 tools 📝 Text & Data 51 tools 💧 Design & Color 43 tools 🌐 Network & API 29 tools 🔧 Dev Utilities 166 tools 🔍 SEO & Performance 45 tools 🤖 AI & Prompts 25 tools
// trending
SPONSORED
87,000+ Premium Templates — One Subscription
WordPress themes, Joomla templates, Shopify themes, plugins & graphics. Unlimited downloads with a commercial license.
WordPress Joomla Shopify HTML
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🎨 CSS (41 tools) View all 41 →
🎨
CSS Fluid Typography Calculator NEW
Build responsive typography scales
CSS Calculator Generator
🎨
CSS Z-Index Visualizer NEW
Understand CSS stacking order
CSS Generator Design
💻
Inline CSS for Email NEW
Inline CSS into email HTML
CSS Email HTML
🎨
CSS Clip Path Generator NEW
CSS Clip Path Generator — free online tool
CSS Generator
🎨
CSS Transform Generator NEW
Generate CSS transform strings visually
CSS Generator Transform
🎨
CSS Variables Extractor NEW
Extract all CSS custom properties from files
CSS Extractor
🎨
CSS Specificity Calculator NEW
Calculate CSS selector specificity score
CSS Calculator
🎨
CSS Unused Detector NEW
Detect unused CSS rules in your project
CSS Detector HTML
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📄 HTML (52 tools) View all 52 →
📋
Mermaid Diagram Editor NEW
Mermaid Diagram Editor — free browser-based tool
Markdown Content
💻
Inline CSS for Email NEW
Inline CSS into email HTML
CSS Email HTML
💻
Hero Section Generator NEW
Generate hero section HTML
Generator HTML Markup
🎨
CSS Unused Detector NEW
Detect unused CSS rules in your project
CSS Detector HTML
💻
HTML Sitemap Generator NEW
HTML Sitemap Generator — free online tool
HTML Generator Sitemap
💻
HTML Minifier NEW
Minify HTML to one line
HTML Minifier
💻
HTML Entity Encoder NEW
Encode and decode html entity
HTML Encoder Decode
💻
HTML Meta Tag Generator NEW
HTML Meta Tag Generator — free online tool
HTML Generator Meta
⚡ JavaScript (58 tools) View all 58 →
{ }
JSON Lines Formatter NEW
Format NDJSON and JSONL files
JSON Formatter Developer
📝
Paragraph Counter NEW
Count paragraphs in text
Text Utility Formatter
📝
Text Column Aligner NEW
Align plain-text columns neatly
Text Utility Formatter
{ }
JSON Formatter NEW
Format & validate JSON instantly
JSON Formatter Developer
{ }
JSON Duplicate Key Detector UPDATED
Detect duplicate keys in raw JSON
JSON Developer API
{ }
JSON to C# Class UPDATED
Generate C# models from JSON
JSON Developer API
📝
Unicode Normalizer UPDATED
Normalize Unicode text forms
Unicode Text Utility
📝
Line Wrap Tool UPDATED
Wrap text to a target line length
Text Utility Formatter
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🔐 Encoding & Security (41 tools) View all 41 →
🔐
Base32 Encoder / Decoder NEW
Encode and decode Base32 data
Encoding Security Utility
🔐
Checksum Verifier NEW
Verify file checksums quickly
Encoding Security Utility
🖥️
htpasswd Generator NEW
htpasswd Generator — free online tool
PHP Generator Password
🔐
Data URI Generator UPDATED
Generate Data URI strings
Data Generator Encoding
🔐
Nano ID Generator UPDATED
Generate Nano ID strings
Generator Encoding Security
🔧
Base64 Encode/Decode UPDATED
Encode & decode Base64 data
Base64 Encoding Images
🔧
Password Generator UPDATED
Password Generator — free online tool
Password Security Generator
🔧
URL Encoder/Decoder UPDATED
Encode & decode URLs safely
URL Encoding Web
📝 Text & Data (51 tools) View all 51 →
📋
Mermaid Diagram Editor NEW
Mermaid Diagram Editor — free browser-based tool
Markdown Content
📝
Paragraph Counter NEW
Count paragraphs in text
Text Utility Formatter
📝
Text Column Aligner NEW
Align plain-text columns neatly
Text Utility Formatter
📝
Unicode Normalizer UPDATED
Normalize Unicode text forms
Unicode Text Utility
📝
Line Wrap Tool UPDATED
Wrap text to a target line length
Text Utility Formatter
🔧
Markdown Previewer UPDATED
Preview Markdown live
Markdown Preview Content
💻
HTML ↔ Markdown Converter UPDATED
Convert HTML ↔ Markdown
HTML Markdown Converter
🎨
CSS Text Shadow Generator
Generate layered text-shadow effects
CSS Text Generator
SPONSORED
87,000+ Premium Templates — One Subscription
WordPress themes, Joomla templates, Shopify themes, plugins & graphics. Unlimited downloads with a commercial license.
WordPress Joomla Shopify HTML
from$14/mo
Get MonsterONE →
Cancel anytime · Commercial license
💧 Design & Color (43 tools) View all 43 →
🖼️
Image Aspect Ratio Detector NEW
Detect image aspect ratios
Image SVG Design
🖼️
Image Converter NEW
Convert image formats
Images Utility Converter
🖼️
Image Cropper UPDATED
Crop images in the browser
Image SVG Design
🖼️
Noise Texture Generator UPDATED
Generate subtle noise textures
Generator Image SVG
🔧
Base64 Encode/Decode UPDATED
Encode & decode Base64 data
Base64 Encoding Images
🔧
Color Converter UPDATED
Convert color formats
Color Converter Design
🖼️
SVG Path Viewer
Preview SVG path commands visually
SVG Viewer Image
🖼️
SVG Path Simplifier
Simplify complex SVG paths
SVG Image Design
🌐 Network & API (29 tools) View all 29 →
🌐
Apache Redirect Generator NEW
Generate Apache redirect config
Generator Network Web
🌐
IPv6 Compression / Expansion Tool UPDATED
Compress and expand IPv6 addresses
IPv6 Network Web
🌐
ETag Generator
Generate ETag values from content
Generator Network Web
🌐
Redirect Rule Builder
Generate redirect rules quickly
Builder Network Web
🌐
Nginx Redirect Generator
Generate Nginx redirect config
Generator Network Web
🌐
Security Header Checker
Check common security headers
Checker Network Web
🌐
Webhook Signature Verifier
Verify webhook signatures locally
Network Web HTTP
🌐
CIDR Range Expander POPULAR
Expand small CIDR ranges
CIDR Network Web
SPONSORED
Fast, Reliable Web Hosting for Your Next Project
SSD storage, free SSL, 99.9% uptime guarantee, and 1-click WordPress installation. Trusted by thousands of developers.
Free SSL 99.9% Uptime WordPress Ready
from$2.99/mo
View Hosting Plans →
30-day money-back guarantee
🔧 Dev Utilities (166 tools) View all 166 →
{ }
JSON Lines Formatter NEW
Format NDJSON and JSONL files
JSON Formatter Developer
🔐
Base32 Encoder / Decoder NEW
Encode and decode Base32 data
Encoding Security Utility
🔐
Checksum Verifier NEW
Verify file checksums quickly
Encoding Security Utility
📝
Paragraph Counter NEW
Count paragraphs in text
Text Utility Formatter
📝
Text Column Aligner NEW
Align plain-text columns neatly
Text Utility Formatter
🔧
dotenv Parser NEW
Parse .env files safely
Parser Developer Utility
🔧
Rate Limit Calculator NEW
Estimate API rate limits
Calculator Developer Utility
📦
Screen Resolution Tester NEW
Preview designs at common screen sizes
Utility
🔍 SEO & Performance (45 tools) View all 45 →
💻
Hero Section Generator NEW
Generate hero section HTML
Generator HTML Markup
🔍
FAQ Rich Result Preview NEW
Preview FAQ rich result markup
FAQ Preview SEO
🔍
Open Graph Tester NEW
Test open graph live in the browser
SEO Performance Open Graph
💻
Timeline Generator UPDATED
Generate timeline section markup
Generator HTML Markup
🔍
Structured Data Tester Lite UPDATED
Inspect structured data blocks
Data Tester SEO
💻
HTML Accessibility Quick Audit
Check HTML for common accessibility issues
HTML Generator Markup
💻
Accordion Generator
Create accessible accordion markup
Generator HTML Markup
💻
Tabs Generator
Generate accessible tabs markup
Generator HTML Markup
🤖 AI & Prompts (25 tools) View all 25 →
🤖
Prompt Variable Extractor NEW
Extract variables from prompt templates
Prompt Extractor AI
🤖
Prompt Version Comparator NEW
Compare prompt versions side by side
Prompt Comparator AI
🤖
AI Model Comparator NEW
Compare and diff ai model
AI Prompts Comparator
🤖
Prompt Diff Viewer UPDATED
Show differences between prompts
Prompt Viewer AI
🤖
Embedding Cost Estimator UPDATED
Estimate embedding job size
AI Prompt Dataset
🤖
Prompt Test Case Builder
Generate prompt testing scenarios
Prompt Builder AI
🤖
Prompt Parameter Matrix
Build prompt parameter combinations
Prompt AI Dataset
🤖
Prompt Sanitizer POPULAR
Clean prompts before sharing
Prompt AI Dataset
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