カウントダウン タイマー

ストップウォッチ with centisecond precision, lap and split timing

Standard Pomodoro timer: 25min focus + 5min break

View current time in 10 major cities with live second refresh

Monthly calendar with today/weekend highlighting and quick navigation

Validate, pretty-print or minify JSON with error line:col reporting

Merge multiple PDF files in sequence, all processed locally in browser

Generate cryptographically secure passwords with custom length and charset

Format convert, remux, mute, rotate, flip, reverse, speed change, watermark via FFmpeg