Free developer tools,that never phone home.
24 utilities for the things you do a hundred times a week — format a JSON payload, test a regex, diff two files, hash a string, hit an endpoint. Every one runs in your browser, so pasting a production payload or an API key is safe by construction.
Data & Formats
6 toolsFormat, validate, and convert between JSON, XML, YAML, and CSV.
JSON Formatter
Format, prettify, and validate massive JSON strings instantly. No server round-trips — entirely client-side.
CSV ↔ JSON
Convert CSV to JSON and JSON to CSV instantly. Handles headers, nested objects, and custom delimiters. Perfect for data migration and API work. 100% browser-based.
JSON ↔ YAML
Convert JSON to YAML and YAML to JSON instantly. Perfect for Kubernetes, Docker Compose, CI/CD configs, and API specs. 100% browser-based — private and free.
JSON ↔ XML
Convert JSON to XML and XML to JSON instantly. Two-way conversion with formatting, validation, and 100% browser-based privacy — no data ever leaves your device.
SQL Formatter
Format messy SQL into something readable, or minify it back down. Understands string literals, comments, and quoted identifiers, so keywords inside your data are never mangled.
SQL Table Builder
Design a table visually and get correct CREATE TABLE SQL for PostgreSQL, MySQL, SQLite, or SQL Server — with the right identifier quoting, auto-increment syntax, and type names for each.
Text & Code
6 toolsRegex, diffs, case conversion, Markdown, and word counts.
Regex Tester
Test your regular expressions against sample text in real-time with live match highlighting.
Diff Checker
Compare two strings or code blocks to find exact differences line by line with color highlighting.
Base Converter
Convert between binary, octal, decimal, hex, and any base from 2 to 36, with a bitwise playground and two's complement views. Uses BigInt, so 64-bit values convert exactly.
Text Converter
Instantly convert strings between camelCase, snake_case, PascalCase, UPPER CASE, and more.
Markdown Preview
Write and preview Markdown in real time. Convert Markdown to HTML with a live editor, toolbar, and instant rendering.
Word Counter
Count words, characters, sentences, and paragraphs. See reading time, speaking time, and keyword density.
Security & Encoding
5 toolsBase64, cryptographic hashes, and secure password generation.
Password Generator
Generate cryptographically secure passwords, passphrases, and PINs with strength scoring and crack-time estimates.
Hash Generator
Generate MD5, SHA-1, SHA-256, SHA-384, and SHA-512 hashes for text and files. Verify file integrity instantly.
Base64 Encoder
Securely encode or decode strings to and from Base64 directly in your browser.
JWT Decoder
Decode a JSON Web Token and read its header, payload and standard claims with expiry worked out for you, verify the signature against the real key, or sign a new token. Runs entirely in your browser, so pasting a real token or key does not hand it to anyone.
UUID Generator
Generate UUID v4, time-ordered UUID v7, ULIDs, and short IDs in bulk, using the browser's cryptographic random source. Explains when v7 beats v4 as a database key.
Web & APIs
7 toolsTest endpoints, parse URLs, convert timestamps, and pick colors.
API Client
Test REST APIs directly in your browser. Supports all HTTP methods, headers, auth, collections, history, and environment variables.
URL Parser
Break down complex URLs into individual components — query params, protocol, host, and more.
Cron Generator
Build a cron schedule from pickers or paste one and get it explained in plain English, with the next five run times. Handles the day-of-month and day-of-week OR rule most tools get wrong.
Timestamp Converter
Convert Unix epoch time to a human date and back, in seconds, milliseconds, microseconds, or nanoseconds. Auto-detects the unit, shows ISO 8601 and local time, and handles dates before 1970.
Time Converter
Convert between 24-hour and 12-hour time formats instantly. Supports bulk conversion and military time.
Color Picker
Pick colors and convert between HEX, RGB, HSL, and CMYK formats. Check contrast ratios for accessibility.
QR Code Generator
Generate QR codes for URLs, text, WiFi, email, and phone numbers. Customize colors and size, then download as PNG.
Safe to paste into
No request ever carries your input off the page, so a production payload, a JWT, or a customer CSV is as safe here as in your own editor. Open DevTools and check the network tab — that is the whole argument.
No account, no limits
There is no free tier that runs out at five conversions, no watermark, and no email wall. Bookmark a tool and it behaves identically on the hundredth use as the first.
Documented, not guessed
Each tool ships with a reference guide — the JSON parse-error decoder, a regex cheat sheet that actually compiles, hash algorithms marked broken or safe, and HTTP status codes in plain English.
Free developer tools that run entirely in your browser
Every developer keeps a scratch folder of half-remembered utilities: the site that pretty-prints JSON, the one that tests a regular expression, the one that decodes a JWT so you can see what the backend actually put in it. The trouble is that most of them send your input to a server to do the work. That is fine for a toy example and genuinely dangerous for a real payload, because a bearer token pasted into a “free online decoder” is a token you have to rotate.
These 24tools do the processing in the page itself. There is no API behind them and no request carrying your data anywhere — which you can verify in about ten seconds with your browser’s network tab. That single design choice is what makes it reasonable to paste a production response into the JSON formatter, drop a config into the YAML converter, or run a real string through the hash generator.
The set covers the everyday loop rather than trying to be exhaustive: converting between JSON, XML, YAML and CSV; testing regular expressions with live match highlighting; comparing two blocks of text with a real diff algorithm; encoding and decoding Base64; generating MD5 through SHA-512; building secure passwords; and calling REST endpoints from an in-browser API client when you do not want to open Postman for one request.
Each page also carries a written reference — the kind of thing you would otherwise go hunting for on Stack Overflow. If you came looking for a calculator or a file tool instead, the everyday tools are on the home page.