All Tools
Quick tasks
One click opens the tool already set up for the job.
Free Online Developer Tools That Run in Your Browser
Every tool on this page does one job, does it immediately, and does it without asking who you are. There is no account, no free tier, no upload limit and no watermark. Paste something in, get the result, close the tab.
The more important property is where the work happens. Everything here runs as JavaScript inside your own browser. The text you paste is never sent anywhere, which matters because the data a developer most often needs to format, decode or hash is exactly the data they are least free to hand to a stranger: a production API response, an access token, a customer record, a config file with credentials in it.
Pick a tool by what you are trying to do
| I need to… | Tool |
|---|---|
| Read an API response that arrived as one unreadable line | JSON Formatter |
| Write a pattern for a log filter or a validation rule | Regex Tester |
| Turn JSON into YAML, CSV or XML, or back again | JSON Converter |
| See exactly what changed between two versions of a text | Text Compare |
| Switch text between UPPER CASE, Title Case, camelCase or a URL slug | Case Converter |
| Count words and characters, or remove duplicate lines from a list | Word Counter |
| Preview Markdown, or turn HTML into Markdown | Markdown to HTML Converter |
| Embed an image in CSS, or read what an API key contains | Base64 Encoder |
| Fix a link that breaks at the first space or ampersand | URL Encoder |
| Read a hex or binary value as a number, or text as bytes | Number Base Converter |
Escape text for HTML, or decode & and friends back to text | HTML Entity Encoder |
| Create a primary key, correlation ID or collision-proof filename | UUID Generator |
| Create a credential nobody can guess | Password Generator |
| Move a link from a screen or a printed page onto a phone | QR Code Generator |
| Design a gradient, a box shadow or rounded corners and copy the CSS | CSS Generator |
| Get an image into the format something else will accept, or several into one PDF | Image Converter |
| See whether a photo gives away where it was taken, and remove its hidden data | EXIF Viewer & Remover |
| Merge PDFs, split one, or extract, delete and rotate pages | PDF Tools |
| Turn PDF pages into JPG or PNG images, or pull out the text | PDF Converter |
| Make a PDF small enough for an email or an upload form | PDF Compressor |
| Read a QR code from a screenshot, a photo or the camera | QR Code Reader |
| Turn a HEX colour into RGB or HSL for a stylesheet | Color Converter |
| Verify a download, or fingerprint a file | Hash Generator |
| Work out what time a Unix timestamp in a log actually was | Timestamp Converter |
| See the claims inside a token that is being rejected | JWT Decoder |
| Make minified HTML, CSS, JavaScript or SQL readable, or minify it | Code Formatter |
| Check what a crontab line means and when it runs next | Cron Expression Explainer |
| Work out the host range, mask or broadcast address of a subnet | Subnet Calculator |
| Find out which browser, device or crawler sent a request | User-Agent Parser |
| Get TypeScript, Go, Python or C# types from a JSON response | JSON to Types |
| Write the meta and Open Graph tags that shape search results and shared links | Meta Tag Generator |
| Strip the CSS a page never uses, from a Chrome recording or the HTML | Unused CSS Remover |
The six groups, and what belongs in each
Text tools handle the formats developers read all day. The JSON formatter indents, validates and minifies, and when parsing fails it names the offending character rather than shrugging. The JSON converter moves data between JSON, YAML, CSV and XML, Text Compare shows what changed between two versions line by line, and the regex tester runs your pattern against sample text as you type, so you find out about the greedy quantifier before production does.
Encoding tools reshape data so it survives a channel that would otherwise break it. The Base64 encoder handles both the standard and URL-safe alphabets, which is the usual reason a token decodes in one place and not another. The URL encoder percent-encodes a value or a whole URL — and knowing which of the two you want is most of the skill. The number base converter reads binary, octal, decimal and hex, and turns text into bytes and back.
Generator tools produce things that must be unguessable or unique: UUIDs in five versions, passwords and passphrases, and QR codes for links, Wi-Fi credentials and contact details. The CSS generator belongs here too: it builds gradients, box shadows and rounded corners from sliders, and the meta tag generator writes the tags that shape search results and shared links. The randomness comes from your browser's cryptographic generator rather than Math.random, which is the difference between a secret and a guessable string.
Image tools start with the image converter: WebP, PNG, JPG, ICO and PDF output, compression to a size in KB and resizing, with a quality setting that actually matters — dropping from 100 to 85 typically halves the file with no visible change. The EXIF viewer shows the hidden data in a photo, including its GPS position, and removes it without re-compressing the image, and the QR code reader decodes a code from a screenshot or the camera.
PDF tools merge, split and organize PDF files with page previews: merge, split, extract, delete and rotate pages without uploading the document, the PDF converter turns pages into JPG or PNG images or plain text, and the PDF compressor reduces the file size, down to a limit such as 1 MB if needed.
Developer tools are the small conversions that interrupt real work: colour notations, MD5, SHA and bcrypt hashes, Unix timestamps, JWT payloads, minified code, unused CSS, cron schedules, IP subnets, user-agent strings and types generated from JSON.
What running in the browser actually buys you
- Nothing is transmitted. Open your browser's network panel, paste a large payload, run the tool, and watch that no request leaves the page.
- It works offline. Once a tool page has loaded, it keeps working without a connection.
- There is no size limit imposed by a server — only what your own machine can comfortably handle.
- Nothing is logged. No server sees the input, so no server can retain it, be breached for it, or be compelled to produce it.
- It is fast. No upload, no queue, no round trip. Output appears as you type.
That includes the image converter. It used to send files to the server for encoding; since August 2026 it decodes and re-encodes images with your browser's own image engine, PDFs included, so no tool on the site uploads what you give it.
Every tool ends with a reference article
A tool that only does the thing is half a tool. Each page here closes with a long-form article on the format itself: what it is, how it is built, the mistakes that actually happen, and how it relates to the neighbouring tools. If you have ever wondered why Base64 output is exactly 33% larger, when to reach for UUID v7 instead of v4, or why hashing a password with SHA-256 is a bug rather than a shortcut, the answer is on the relevant page.
Common questions about this collection
- Is there a catch? No account, no paywall, no usage cap, and no feature held back for a paid tier.
- Can I use these at work? Yes. Because processing is local, using them does not transfer your employer's data to a third party — which is usually the blocker with online tools.
- Are they suitable for automation? For scripted workflows you want the equivalent library in your own codebase. These are built for the one-off manual check, which is most of what a developer actually does with them.
- Which languages is the site in? Eight: English, German, Spanish, Portuguese, French, Persian, Arabic and Japanese, with Persian and Arabic laid out right to left.