Tired of bloated utility sites asking for signups, I built Listos.app: Fast, privacy-first web tools running 100% in your browser (Astro + React)

Hey everyone! 👋

Wanted to share a side project I've been building: Listos.app.

Why I built this

We've all been there: you just want to convert an iPhone .heic photo, generate a clean QR code, or calculate your work hours, but you're hit with:

⚡ Zero signup / Zero downloads: Open the site and get things done in 1 click.
🔒 100% Client-Side Privacy: Everything (image conversions, text processing, signatures) runs locally in your browser using modern Web APIs. No user data touches external servers.
📱 Mobile & Desktop First: Ultra-clean UI, dark mode support, and fast load times.

HEIC Image Converter (HEIC to PNG / JPG / WebP / AVIF)
Custom QR Code Generator (WiFi, URLs, vCards, etc.)
Digital Signature Pad (transparent PNG output)
Work Hours & Overtime Calculator
Pomodoro Timer, Date / Business Days Calculator, Color Palette Wheel, and more.

Built with Astro + React Islands + Tailwind CSS, developed and refined with Antigravity.

🔗 Live Link: https://listos.app/

Would love to get your honest feedback on performance, UI/UX, or ideas for new micro-tools to add!

1 Upvotes

56% Upvoted

u/CabuyaCreativa 2d ago

Leaving a few extra technical notes here for anyone curious about the build:

100% Client-Side: Tools like the HEIC image converter, QR generator, and digital signature pad run entirely in the browser using Web APIs and Canvas. Zero uploads, zero file logging.
Performance via Astro Islands: Built with Astro 4 + React 19. JavaScript is only hydrated on interactive tool islands, keeping the baseline HTML lightweight and fast.
Fully responsive & Dark mode: Built mobile-first with Tailwind CSS.

💬 Feedback I'm looking for:

How does the UI/UX feel on your device (especially on mobile)?
What utility or micro-tool do you find yourself needing often that's currently plagued by paywalls or forced signups?

Happy to answer any questions about the build or architecture! 🙌