I tried to build a “trustless” file sharing app (browser-only)

Chuan Hu — Tue, 28 Apr 2026 16:09:04 +0000

I build Figma plugins, but recently I ran into a problem:

I needed to share files (PDF / PPT / assets),
and I realized I don’t actually trust any file sharing service.

Not because they’re bad — but because:

they can technically read your files.

So I tried something different

I’m building a file sharing flow where:

everything happens in the browser
files are encrypted before upload
server stores only opaque blobs
the decryption key is in the URL (#key=...)

Meaning:

if you don’t have the link, you literally can’t read the file
even I (the developer) can’t access it

The interesting parts

Users upload anything:

PDF / PPT / Word / images

Trying to normalize formats inside the browser is way harder than expected
(WASM helps, but still messy)

Web Crypto API works great.

The real issues are:

large files (100MB+)
memory spikes
blocking UI

→ solution: chunking + Web Workers

Users don’t care about encryption.

They want:

drag & drop
click “create link”
done

Making something secure feel this simple is the real challenge.

Why I’m sharing this

I’m starting to think:

“trustless apps” might be a real category

Where you don’t need to trust:

the platform
the backend
even the developer

Curious if anyone here has built:

browser-only file processing
large file encryption pipelines
WASM-heavy apps

Would love to hear how you handled performance.

DEV Community: Chuan Hu