Developer Tools
Code formatters and validators
CSS calculators and visual tools
Configuration and security generators
100% local and private processing
Web Development
Free web development tools: formatters, CSS calculators, generators and utilities for frontend and backend developers.
Free Online JSON Formatter and Validator
Free online tool to format, validate and repair JSON code. Beautify and format JSON. Detects syntax errors and improves code readability.
Free Online SVG to CSS and Data URI Converter
Transform your SVG icons and vectors into CSS code (Background or Mask) or compressed Data URI. Optimise your website performance by eliminating external HTTP requests.
Aspect Ratio Calculator in Pixels. Online Proportions
Calculate new image, video and web design resolutions and maintain the exact proportion to avoid distorting graphics. Supports 16:9, 4:3, 21:9 and custom formats.
Placeholder Image Generator. Rapid Web Mockups Online
Create custom placeholder images for your web designs. Adjust resolution, background, text and export in PNG, WebP or JPEG instantly.
URL Encoder and Decoder Online
Convert special characters from any link to safe format (Percent-Encoding) or return them to their original readable state instantly and locally.
Duplicate CSS Remover Online. Unify and Clean Stylesheets
Free tool to clean and purge duplicate CSS code. Unifies redundant selectors, respects the cascade, and reduces your file size instantly in the browser.
CSS to Inline HTML Converter. Inliner for Emails
Transform your stylesheets and CSS classes into automatically inlined styles in your HTML. Ideal for newsletters, transactional emails, and safe web layout.
CSS Specificity Calculator Online. Selector Weight Visualizer
Calculate the specificity and exact weight of any CSS selector. Visual tool to understand which CSS rule wins the cascade and avoid using !important.
Online Cron Expression Generator. Translator and Visualizer
Free visual tool to generate Linux Cron expressions. Translates * * * * * into human language and shows the next 5 executions in real time.
Online Keyboard Key Code Visualizer. KeyCode Inspector
Free online tool to see the event.key, event.code, event.which and location of any keyboard key in real time. Generates ready-to-use JavaScript code snippets.
LLM Cost Calculator. AI Model Pricing Estimator
Free online tool to estimate the cost of calling LLM APIs. Compare GPT-4o, Claude, Gemini, Llama and more with real token prices per million tokens.
Musical Typography Scale. Modular Scale Calculator
Free online tool to create harmonious visual hierarchies using modular scales based on musical proportions. Generates ready-to-use CSS variables for your web design.
Mobile Mockup Generator for App Store. iPhone and Google Pixel
Create professional presentations for the App Store and Google Play. iPhone and Pixel mockups with custom backgrounds, panoramic layouts, and bulk high-resolution export.
Online Security Hash Generator
Calculate MD5, SHA-1, SHA-256 and SHA-512 hashes instantly. Free, private and ultra-fast security tool for developers. 100% Client-Side.
Private AI Prompt Library
Organize, tag and save your ChatGPT, Midjourney and Claude prompts privately. Your own prompt bank in localStorage.
Online Color Converter RGB HEX and HSL
Convert colors between RGB, HEX and HSL instantly. Generate complementary color harmonies and analyze WCAG contrast. 100% client-side and private.
Visual Readability Calculator WCAG and APCA
Check the real contrast of your designs with APCA (WCAG 3.0). Analyze how font weight and size affect actual readability. From simple ratios to perceptual legibility.
Online SVG Sanitizer
Optimize and clean SVGs exported from Figma, Adobe Illustrator or Inkscape. Remove metadata, unnecessary attributes and empty groups to get a production-ready SVG.
UTM Parameter Generator for Google Analytics
Create precise tracking links for your digital marketing campaigns. Optimized for Google Analytics and other analytics tools.
URL Tracking Cleaner: Remove UTM, FBCLID and GCLID
Automatically remove tracking and advertising parameters from your URLs. Share clean links and protect your digital privacy instantly.
Online SSL/TLS Certificate Inspector View PEM and CRT Files
Analyze SSL certificate files (.pem, .crt, .der) locally. Check expiration dates, issuers, subjects and SHA-256 fingerprints without your data leaving your browser.
Security.txt Generator RFC 9116
Create your professional security.txt file to facilitate vulnerability reporting and comply with international web security standards.
Data Time Calculator Impact of Web Speed
Discover how much lifetime your users lose waiting for your website to load on 3G, 4G, and 5G connections. Calculate the real impact of your site weight.
Excel and CSV to HTML Table Converter Code Generator
Convert your Excel or CSV data to clean, semantic HTML tables instantly. Free tool for developers and content creators.