DevToolbox

Optimize PDF images and fonts locally using the Ghostscript engine. Efficient batch processing with maximum privacy.

Edit PDF online, support adding text, images, signatures, watermarks, and free drawing

Powerful Go AI powered by KataGo engine. Features real-time analysis, win-rate prediction, and multiple levels.

Online chess game with Stockfish WASM engine, supporting multiple difficulty levels and position analysis

Traditional Chinese Chess (Xiangqi) against intelligent AI

Play Gomoku against AI with various difficulty levels, runs locally in browser

P2P file transfer using WebRTC, end-to-end encrypted

1-to-N file sharing via WebRTC, generate QR to let multiple clients download

Real-time weather forecast and air quality for global cities

Casio-style online scientific calculator supporting various math operations

Generate QR codes from text or URLs

Universal unit converter for length, mass, area, volume, temperature, etc.

Real-time counter for words, characters, lines, CJK characters, reading time

Generate secure random passwords

Efficient batch and bulk image compression tool. Adjust quality and dimensions locally in your browser for maximum privacy.

Convert between PNG, JPG, and WebP

All-in-one visual tool to merge, split, reorder, rotate or remove PDF pages with ease

Convert multiple images to a single PDF, with support for reordering and page settings

Calculate the future value of savings or investments with compound interest

Calculate monthly payments and total interest for loans

Mortgage calculator supporting commercial, provident fund, and combined loans with LPR support.

P2P video call using WebRTC, end-to-end encrypted, no server mediation

Online crop, resize, blur, and basic editing tool

Global timezone conversion and visual comparison

A lightweight online eBook reader, supports importing local EPUB files

Calculate Body Mass Index (BMI), assess weight health status, provide ideal weight reference

Online tool to create exam cheatsheets by automatically arranging text to maximize space, supports PDF export.

Play Othello against AI, test your strategy with this classic board game

Play Checkers against AI, test your strategy with this classic game

Powerful Backgammon AI powered by GNU Backgammon WASM engine with world-class neural network evaluation

Professional online typing practice and speed test tool. Supports English/Chinese, multiple modes, and real-time accuracy statistics.

Create mind maps online with dual outline/visual views, beautiful themes, and multiple export options.

Privacy-focused free temporary email service. Protect privacy and prevent spam.

All-in-one timer: real-time clock, stopwatch, and countdown — all with fullscreen support