How to use Claude to build QR code file sharing
Safronov reported an instant tax-file download at the library. Engye grew to support sending and collecting files, clipboard sharing and a virtual drive.
news.ycombinator.com
Prompt to try
Editorial adaptation, not the source author’s exact prompt. Replace bracketed inputs and review tool permissions first.
Implement [file-sharing app] as a static [frontend] site connecting two browser instances through WebRTC and a QR code. Support [document types] without accounts, then help iterate on [additional features]. Identify memory and session limitations.
Reach people exploring AI agents
See placements →What happened
Safronov reported an instant tax-file download at the library. Engye grew to support sending and collecting files, clipboard sharing and a virtual drive.
Reported by psafronov on Hacker NewsHow the agent did it
- Designed a QR-based file transfer app and instructed Claude to implement it.
- Used the first version to transfer a tax file at the library.
- Investigated alternatives after the library trip.
Where a person stepped in
The author designed the app and used it at the library; the post does not describe formal code review.
A person approved each step before the agent continued.
Pavel Safronov wanted to print tax forms at a library without typing account credentials, plugging in a drive or uploading the forms to another website. He designed Engye and instructed Claude to implement it, then developed the application through conversations with Claude over about three months.
The first version was a static Vite TypeScript site hosted on GitLab Pages. It used a QR code to connect two website instances through WebRTC. At the library, Safronov opened the site on the public computer, scanned its code with his phone and selected the tax file. He reported that the computer downloaded it instantly.
After that trip, he investigated alternatives and expanded the project with file collection, shared clipboard text and a virtual drive. The post describes browser-to-browser encryption using AES-256-GCM, with the key carried in the QR code. Closing the browser ends the connection. Safronov also identified a limitation: large files can crash the browser because data is loaded into memory twice. Who it's for: developers building small document-transfer tools for devices where installing software or signing into accounts is inconvenient.
Prompt
Suggested prompt (written by Agents In Use, not the author's)
Source: Hacker News · psafronov
Frequently asked questions
How did the library transfer work?
The author opened the website on the library computer, scanned its QR code with his phone and selected the tax file; the computer downloaded it instantly.
What file-size limitation did the author identify?
The author says large files can crash the browser because the application loads the data into memory twice.
More details
Remaining steps
- Iterated with Claude to add sharing features and a virtual drive.
About this account
Claude implemented the author’s design and supported iterative development through conversations over about three months.
Platform: Hacker News. Attribution: https://news.ycombinator.com/item?id=48703194. Prompt: Suggested (written by Agents In Use, not the author's). Sourced by the Agents In Use pipeline.
Credit: psafronov on Hacker News
Source published 28 Jun 2026
Source checked 14 Oct 2026
Tools and topics
Claude · Vite · GitLab Pages · WebRTC
File sharing · QR codes · WebRTC
Editorial completeness: 100/100. Measures documented fields, not agent performance or verified outcomes.