About HCODX

One platform for everything you write, run, calculate, and ship.

HCODX is a free, browser-based AI & developer platform. It combines a live-preview HTML/CSS/JS editor, an advanced VS Code-style IDE, a Calculator Hub (financial, fitness, math, date, pets and more), an AI Tools Hub (token counters, cost calculators, AI detectors, humanizers), JSON-to-code generators in many languages, document and image viewers, and a full suite of formatters, converters, encoders and generators — all running locally in your browser. No installs, no signup, no file uploads.

Open Editor

hello.js — HCODX

// Live preview, instantly in your browser
function greet(name) {
 return `Welcome to HCODX, ${name}`;
}

console.log(greet("developer"))

Live

Instant preview

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Tools & calculators

Editor modes

Signup required

What is HCODX

A complete coding & calculation environment — in a tab.

HCODX (pronounced H-Code-X) is a high-performance, privacy-first platform built for developers, students, educators, freelancers and anyone who needs a quick, trustworthy calculator. Every product on HCODX runs directly in your browser: your code, files and calculator inputs stay on your device, the interface is fast, and you can move from idea to running code — or from question to answer — in seconds. No signup. No file uploads.

The platform is organised into three hubs and many supporting toolboxes: the HTML/CSS/JS Editor with live preview, the Calculator Hub covering finance, fitness, math, date and pets, the AI Tools Hub for everything else — formatters, converters, generators, encoders, network/security utilities, AI token counters and cost calculators, JSON-to-code generators, document and image viewers, and more.

Editors

One fast editor. Zero setup.

A fast, distraction-free HTML/CSS/JS playground with instant live preview — right in your browser.

HTML Editor

HCODX Editor

A fast, lightweight HTML, CSS, and JavaScript editor with instant live preview, integrated console, and local-storage persistence — beginner friendly, zero setup.

Open Editor

Built-in editor capabilities

Live previewReal-time rendering of HTML, CSS, and JavaScript as you type.
Multi-file projectsFile tree, tabs, and project persistence — manage real codebases.
Syntax highlightingMonaco-powered highlighting for HTML, CSS, JS, TS, Vue, JSX, and more.
Integrated consoleDebug JavaScript directly inside the editor — logs, errors, traces.
NPM modules (VS Editor)Import packages from NPM and use frameworks like React or Vue.
Auto-format & lintOne-click Prettier formatting and on-the-fly validation.
Light & dark themesEditor and UI follow your OS preference automatically.
One-click exportDownload your project as ready-to-deploy HTML/CSS/JS files.
Responsive previewPreview your site at any device size from the built-in emulator.
Runs offline-capableMost editor features work without a server round-trip.

Calculator Hub

Every calculator you need — finance, fitness, math, dates, pets & more.

The Calculator Hub at /calculator is a single dynamic page that hosts a full catalog of free in-browser calculators across four categories. Every calculator runs locally, uses verified formulas (cited inline), and lives at a clean SEO-friendly URL like /calculator/mortgage or /calculator/bmi.

Financial

Mortgage, loan, auto loan, retirement, investment, compound interest, salary, tax bracket (US 2025), capital gains, self-employment tax, VAT, UK PAYE, UK NI, Inheritance Tax, Dividend Tax, Corporation Tax, net worth, pay raise, cost of living, crypto profit and many more.

Mortgage Loan Retirement Tax Bracket (US) PAYE (UK) IHT (UK) Net Worth Crypto Profit

Fitness & Health

BMI, BMR, TDEE, calorie, body fat, ideal weight, body surface area (BSA), GFR (eGFR), heart rate, max HR, 1RM, VO₂ max, pace, pregnancy, due date, ovulation, conception, BAC, water intake, sleep cycles and others. Educational only — not medical advice.

BMI Calorie TDEE Body Fat Pregnancy BAC GFR Heart Rate

Math & Science

Scientific, fraction, percentage, triangle, quadratic, slope, distance, midpoint, Pythagorean, factorial, nCr / nPr, GCD, LCM, prime factorization, logarithm, exponent, circle / rectangle / sphere / cylinder, statistics, standard deviation, z-score, half-life, molarity and more.

Scientific Percentage Fraction Quadratic Triangle Std Deviation Probability

Date, Time & Pets

Age, date, time, hours, time card, day counter, day-of-week, time-zone, time-duration, countdown, anniversary, plus pet age calculators (dog age, cat age) using AVMA / AAFP standards.

Age Date Countdown Anniversary Dog Age Cat Age

Open Calculator Hub

AI & Developer Tools Hub

A complete dev utility library, online.

Free, in-browser tools across formatters, minifiers, converters, generators, security, network, color, AI, calculators and more — every utility you'd otherwise glue together from scattered sites, unified under one consistent UI and one consistent privacy promise: nothing leaves your browser.

Formatters & Beautifiers

JSON, HTML, CSS, JS, YAML, XML — pretty-print, validate, and lint with a single click.

JSON Formatter HTML Formatter CSS Beautifier JS Beautifier Prettier YAML XML

Minifiers

Compress code for production — HTML, CSS, JS, JSON. Smaller files, faster loads.

JS Minifier CSS Minifier HTML Minifier JSON Minifier Code Unminifier

Converters

Convert between JSON, YAML, XML, TOML, CSV, INI, HTML, Markdown — plus JSON-to-code for 10+ languages.

JSON Converter JSON → YAML CSV → JSON HTML → Markdown JSON → TypeScript JSON → Python Color Converter

Encoding & Security

Base64, URL, HTML entity, hex, hashes, HMAC, bcrypt, JWT decode, AES — encode, decode, verify.

Base64 Hash Generator HMAC Bcrypt Verify JWT Decode Caesar Cipher Checksum

Network & IP

IPv4/IPv6, CIDR, subnet, DNS lookups, IP-to-int — every networking helper a developer needs.

CIDR Calculator IP Converter IPv4 → IPv6 IP → Integer

Generators

UUID/GUID, passwords, lorem ipsum, fake data, QR, favicons, .htaccess, robots.txt, sitemaps.

UUID/GUID Fake Data Favicon Lorem Ipsum Password QR Code

Color & CSS

Color converters, gradient and shadow builders, clamp generator, picker, palette tools.

Color Picker HEX/RGB/HSL Gradient Box Shadow Border Radius CSS clamp() Color Palette Generator

Text & Data Utilities

Case converter, character counter, find/replace, dedupe, diff, regex tester, slugify.

Case Converter Char Counter Find / Replace Deduplicate Code Diff JSON Diff

Validators

HTML validator, JSON lint, YAML/XML validators, schema checkers, link checkers.

HTML Validator JSON Lint YAML Validator XML Validator JSON Schema

AI Tokens & Cost

Token counters and cost calculators for Claude (Opus/Sonnet/Haiku), GPT-4o/5, Gemini, DeepSeek, and more.

Claude Opus Claude Sonnet Claude Haiku GPT-5 GPT-4o Gemini DeepSeek Token Counters

Image & Media

Image to Base64, favicon generation, image compressors, emoji picker, ASCII art.

Image → Base64 Favicon Emoji Picker ASCII Tools

Web & Performance

Lighthouse audits, AMP testing, device emulator, JS obfuscator, AI HTML builder.

Lighthouse Audit AMP Tester Device Emulator JS Obfuscator AI HTML Builder

Browse all tools

Why HCODX

Built around how developers actually work.

Privacy-first

Editor projects stay in your browser. No tracking of your source code, no required accounts.

Built for speed

Optimized payloads, instant cold loads, minimal UI chrome. Designed to keep you in flow.

One platform

Editor, IDE, and tools in one place — replace a dozen open browser tabs.

Any device

Mobile-first responsive UI. Code from a laptop, a tablet, or a phone — anywhere.

No signup

Open a URL, start coding. No email, no password, no friction.

Always free core

Editor and dev tools stay free. Pro features remain optional for power users.

Who uses HCODX

Trusted by developers, students, and teachers worldwide.

Developers

Prototype components, debug snippets, share runnable demos in seconds.

Students

Practice HTML, CSS & JavaScript on any device — perfect for courses, bootcamps, self-study.

Educators

Share live, runnable examples with classrooms — no installs for students.

Teams

Quickly share a reproducible bug case, demo, or formatted dataset — by URL.