I built a free Unix timestamp tool that works offline and has zero ads

Hey r/webdev,

I built a simple tool that does one thing well:

• Live Unix timestamp (updates every second)
• Convert Unix → Human date
• Convert Human date → Unix
• 4 live timezone clocks (UTC, PT, ET, IST)
• Copy buttons that work on mobile
• Works offline after first visit
• No login, no tracking, completely free

Link: timetooldev.netlify.app

Built with vanilla HTML/CSS/JS. One file. No frameworks. No build step.

I plan to add subtle ads later if people actually use it daily. For now, just looking for feedback.

Would you bookmark this? What features am I missing?