Free browser-based utilities that streamline coding tasks with instant text processing, data conversion, and validation capabilities.
DNA / RNA Sequence Generator Generate random DNA and RNA sequences with precise GC content, batch them into FASTA files, and convert between strands without leaving the browser. Built for students, bioinformatics tinkerers, and developers who need quick test data with statistical control that text-based AI assistants cannot reliably provide. How to Use Pick an ...
Try the Tool »CRC Checksum Calculator Compute Cyclic Redundancy Check values instantly for text or file input, choosing from 15 standardized variants across the CRC-8, CRC-16, CRC-32, and CRC-64 families. Verify downloads, validate serial protocol frames, or confirm file integrity without uploading anything — all calculations run locally in your browser. How to Use Type or paste text ...
Try the Tool »LLM Token Count Estimator Paste any prompt, document, or snippet of code and instantly see an estimated token count for GPT-4o, GPT-4 Turbo, GPT-3.5, the o1 reasoning models, Claude 3.x, and Gemini 1.5. The tool runs fully in the browser, updates in real time as you type, and pairs the count with cost figures per ...
Try the Tool »UUID Validator & Decoder Paste any UUID and instantly see whether it is valid, which version it follows (v1 through v8, plus the special Nil and Max UUIDs), and what metadata is hidden inside its bits. The tool decodes v1, v6, and v7 timestamps to a human-readable date, extracts the node ID / MAC fragment ...
Try the Tool »Snowflake ID Generator (Twitter-Style) Generate 64-bit Snowflake IDs using the classic Twitter bit-layout: a 41-bit millisecond timestamp, 10-bit machine/worker ID, and 12-bit per-millisecond sequence. Every ID is produced client-side with BigInt arithmetic, so nothing leaves your browser and bulk generation up to 1000 IDs stays collision-free for a single machine. How to Use Set Count ...
Try the Tool »Semver Version Calculator & Range Tester An all-in-one Semantic Versioning (SemVer 2.0.0) workbench for developers. Validate version strings, compare two versions with strict precedence, test whether a version satisfies an npm/Composer-style range expression (^, ~, x, hyphen, ||, comparison operators), bump a version with major/minor/patch/prerelease increments, and sort large lists of versions with full pre-release ...
Try the Tool »XPath Expression Tester & Evaluator Paste XML or HTML, type an XPath 1.0 expression, and instantly see which nodes match. The tester runs entirely in your browser, highlights matched fragments in the source, and shows a readable summary for node sets, strings, numbers, and booleans. How to Use Paste your XML or HTML document into ...
Try the Tool »SVG Path Visualizer & Editor Paste any SVG path d-attribute and see it rendered live. This tool breaks each command down into its parameters and absolute end point, draws Bezier control-point handles on top of the preview, and rewrites the path between absolute and relative coordinates with configurable precision. It is built for SVG authors ...
Try the Tool »Nano ID Generator Generate cryptographically secure, URL-friendly unique IDs in your browser. The Nano ID Generator produces compact identifiers using crypto.getRandomValues, with full control over length, alphabet, and output format. Default IDs are 21 characters long with the same collision resistance as a UUID v4 — but 41% shorter and safe to drop straight into ...
Try the Tool »CSS Flexbox Generator (Visual) Design Flexbox layouts visually and copy production-ready CSS. Tweak direction, alignment, wrapping, gap, and per-item overrides while a live preview updates instantly. No guessing, no Chrome DevTools round-trips — just pick the container behaviour you need, watch it render, and grab the generated rules. How to Use Pick a flex-direction (row, ...
Try the Tool »JWT Encoder / Builder Build signed JSON Web Tokens directly in your browser. Drop in a header and payload, pick an HMAC algorithm, supply the shared secret, and copy a ready-to-use token for API testing, debugging, or local development. All signing happens with the SubtleCrypto Web API, so your secret and claims never leave the ...
Try the Tool »CUID2 Generator Generate cryptographically secure CUID2 IDs entirely in your browser. CUID2 is a modern, collision-resistant identifier format that combines a high-entropy random salt, monotonic counter, timestamp, and browser fingerprint, then runs the result through SHA3-512 to produce a base36 string. Every ID starts with a letter, so values stay safe to use in databases, ...
Try the Tool »README Badge Generator The README Badge Generator builds pixel-perfect Shields.io-style badges directly in your browser. Pick a preset or craft your own label and message, choose colors and a style (flat, flat-square, for-the-badge, or plastic), and get copy-ready Markdown, HTML, SVG, and data URL output. No external API calls, no network dependency, no broken badges ...
Try the Tool »Identicon / Avatar Generator Turn any string — a username, email, user ID, or wallet address — into a unique visual avatar. The Identicon / Avatar Generator hashes the input deterministically, so the same text always renders the exact same image. No upload, no account, no server round-trip: the avatar is drawn entirely in your ...
Try the Tool »PWA Web App Manifest Generator Build a valid manifest.json file for your Progressive Web App in seconds. Fill in your app’s identity, choose a display mode, pick the icon sizes you ship, and the generator produces clean JSON you can drop straight into your project — plus the matching <link rel="manifest"> tag for your HTML. ...
Try the Tool »SSH Config File Generator Build a clean, syntactically correct ~/.ssh/config without memorizing directive names or hunting down options in the ssh_config man page. Add each SSH host with a visual form, pick presets for common services like GitHub, AWS EC2, or bastion jump hosts, and copy or download the finished config in one click. How ...
Try the Tool ».htaccess Rule Generator Generate ready-to-use .htaccess rules for Apache web servers without memorizing complex directive syntax. Choose from common presets like HTTPS redirection, GZIP compression, browser caching, IP blocking, and more — or build custom rewrite rules from scratch. How to Use Select a preset from the dropdown to quickly add common rule blocks, or ...
Try the Tool »Fake Email Address Generator Generate realistic-looking fake email addresses for testing, development, and prototyping. This tool creates syntactically valid email addresses using common name patterns and popular domain names, perfect for populating test databases, demo environments, or form testing without using real email addresses. How to Use Select your preferred email format from the dropdown, ...
Try the Tool »CSS Keyframe Animation Generator Create CSS @keyframes animations visually with a live preview. Choose from 10 popular presets like bounce, shake, pulse, fade in, slide in, spin, swing, rubber band, flash, and wobble — or build your own custom keyframe animation from scratch. Adjust timing, easing, iteration count, direction, and fill mode, then copy the ...
Try the Tool »Date Countdown Calculator The Date Countdown Calculator lets you create a real-time countdown to any future date or event. Watch the days, hours, minutes, and seconds tick away live on screen. You can also see how much time has passed since a past event, count only working days (excluding weekends), and share your countdown with ...
Try the Tool »Add IO tools to your favorite browser for instant access and faster searching
Scoreboard is a fun way to keep track of your games, all data is stored in your browser. More features are coming soon!
Update: Our latest tool was added on May 25, 2026
Help us continue providing valuable free tools
