LeetTools.dev
Fast, private, client-side developer tools for JSON, JWT, Base64, passwords, UUIDs, and archives.
Run useful developer tools in your browser with a privacy-first workflow and no server-side processing for supported tools.
All Tools
Browse the full toolbox by category. LeetTools.dev includes generators, formatters, encoders and decoders, and archive utilities for everyday engineering workflows.
#Generators
Password Generator
Instantly generate secure, random passwords on LeetTools.dev. Create strong, unique passwords locally in your browser.
Passphrase Generator (XKCD)
Generate memorable, high-entropy passphrases based on the XKCD method. Secure, random, and easy to remember.
Username Generator
Generate creative, cool, and anonymous usernames for games, social media, and developer accounts.
UUID / GUID Generator
Generate UUID v4 (random) and v7 (time-ordered) locally in your browser. Batch copy, formatting options, no server.
#Formatters
JSON Formatter & Validator
Professional, real-time JSON formatter and validator. Prettify, minify, and debug JSON data instantly with a master-class editor.
JSON Diff & Text Diff Viewer
Compare JSON, API responses, configuration files, and plain text locally with line-level and word-level highlights.
#Encoders & Decoders
JWT Debugger
Secure, client-side JSON Web Token debugger. Decode, verify, and analyze JWT headers and payloads instantly in your browser.
Base64 & Base Converter
A powerful, all-in-one suite for Base64, Base32, Base58, and Base62 encoding. Fast, secure, and client-side text conversion in your browser.
#Archives
Archive Extractor
Browse and extract Zip, 7z, RAR, Tar, and more in your browser. Your file never leaves this device. A password field appears only when you might need it.
Archive to Zip
Turn RAR, 7z, Tar, and other archives into a single .zip download in your browser. Your file stays on this device.
Zip Creator
Combine files into a single .zip download. Add an optional password if you want the archive protected. Nothing is uploaded; everything stays on your device. Other archive types (tar, 7z, ...) are not offered here.
#Images
Image Stitcher
Combine multiple images into one downloadable picture. Upload images, drag them on a canvas, choose a layout, and export locally in your browser.
Image Converter
Batch convert PNG, JPEG, WebP, and AVIF images locally in your browser with quality, resize, and ZIP download controls.
Why LeetTools
LeetTools.dev is built for developers who want quick results without sending working data to third-party services. For supported tools, processing happens locally in the browser, which helps reduce privacy risk and keeps workflows fast.
The toolbox covers common tasks such as formatting JSON, decoding JWTs, converting Base64, generating strong passwords, creating UUIDs, and working with archive files. Each tool page also includes supporting reference content so the page stays useful beyond the interactive UI.