Developer Tools

Format and convert JSON, YAML, CSV, tokens and URLs. 24 tools

Developer utilities have a particular privacy problem that most people never think about. The JSON you paste into a formatter is usually a real API response, complete with access tokens, customer records, and internal endpoints. The JWT you decode is a live credential. The config you convert to YAML maps your infrastructure.

Most online tools send all of that to a server for a transformation the browser could perform in a millisecond. These do not. Formatting, validating, diffing, converting between JSON, YAML, and CSV, decoding tokens, testing regular expressions, minifying assets, and parsing URLs and IP ranges all happen in your tab with no network request at all — which also means they keep working on a locked-down network or with no connection.

Code Diff Formatter

Format code diffs

Color Converter

HEX/RGB/HSL.

CSS Minifier

Compress CSS.

CSV to JSON

Convert CSV.

HTML Minifier

Minify HTML.

HTML to Markdown

Convert HTML into clean, configurable Markdown with live preview, GFM tables/task lists, HTML validation, and stats — entirely in your browser.

IP Parser

Parse, validate, and analyze IPv4 and IPv6 addresses — CIDR calculator, classification, conversions, batch mode, all local to your browser.

JS Minifier

Minify, beautify, and validate JavaScript with compression stats, code analysis, and an optimization report — all local to your browser.

JSON Diff

Compare two JSON documents and see exactly what changed — side-by-side, unified, tree, and RFC 6902 patch views, with merge, statistics, and export, all local to your browser.

JSON Formatter

Format, minify, validate, and explore JSON with a collapsible tree view, colorized syntax, and detailed stats — all local to your browser.

JSON to CSV

Convert JSON files and JSON data into CSV format instantly with this free client-side converter. Secure, fast, and works directly in your browser.

JSON to YAML

Convert JSON data into YAML format instantly with this free client-side converter. Secure, fast, and works directly in your browser.

JSON Validator

Validate and format JSON data instantly with this free client-side JSON validator tool. Check JSON syntax, detect errors, and beautify JSON directly in your browser.

JWT Decoder

Decode JSON Web Tokens (JWT) instantly with this free client-side JWT decoder. View the header, payload, signature, and token claims securely in your browser.

Lorem Ipsum Generator

Generate customizable Lorem Ipsum paragraphs, sentences, words, and lists with live stats, presets, HTML/Markdown export, and generation history — all local to your browser.

Markdown to HTML

Convert Markdown into clean, standards-compliant HTML with live preview, syntax highlighting, GFM extensions, and export options — all local to your browser.

Regex Tester

Test, debug, and validate regular expressions with live highlighting, capture groups, replace preview, pattern analysis, and a preset builder — all local to your browser.

Repo-Verse

Drop a project folder and watch it become a 3D solar system: every file a planet sized by bytes, every folder a system, every commit a step in a time-lapse. Your code is read locally through the File System Access API and never uploaded.

Timestamp Converter

Convert Unix timestamps to human-readable dates and back, across any time zone — with batch conversion, world clocks, time difference math, custom formats, and a timestamp generator, all local to your browser.

URL Opener

Open, check and manage lists of URLs — batch open in tabs or an embedded frame, reachability checks, groups, tags, import/export and monitoring, all in your browser.

URL Parser

Parse, validate, and analyze URLs — component breakdown, query string editor, security and phishing checks, normalization, comparison, and batch parsing, all local to your browser.

UUID Generator

Generate UUIDs in every version (v1 through v8, Nil and Max) with bulk generation, validation, timestamp extraction, randomness analysis, and code snippets — all local to your browser.

XML Formatter

Beautify XML.

YAML to JSON

Convert YAML.

All 24 developer tools, free and without an account

Every tool listed above runs entirely inside your browser. Nothing you open is uploaded, there is no sign-up, no file-size limit, and no watermark on anything you export. Pick a tool to get started, or use the search box at the top of the page to jump straight to one.

Each tool page includes a written guide explaining what the tool does, why it works the way it does, and the mistakes that most often catch people out. Longer walkthroughs live on the blog, and you can read more about who builds these and exactly what data we handle in the privacy policy.