r/FastAPI • u/Ahmad_Azhar • 4d ago
Other FastAPI for the backend, Flet for the UI — sharing RelayDeck
Hey everyone! It’s been great seeing FastAPI grow so much and mature over time. It’s now my default choice when building APIs in Python.
I love FastAPI, so I chose it again for this project and paired it with Flet (Cross-platform interfaces in Python). Probably shows how much I love Python too 🙂
RelayDeck, Independent companion for Herdr, which manages coding agents and shell sessions on your Mac. RelayDeck lets you access those sessions from a phone, iPad, or browser.
FastAPI powers the backend API and WebSocket connections, including device pairing and terminal access, while Flet handles the interface.
Here’s what’s available:
- Usage and limits: token usage and estimated costs by tool and Herdr space, with usage history and charts. Where supported, it also shows plan limits and reset times.
- Remote terminals: open an agent or shell, check its output, send a prompt, or answer a question directly.
- Image attachments: attach screenshots and images to prompts, with support for PNG, JPEG, and WebP.
- Different ways to type: a composer for longer prompts, direct terminal input, and ordinary shell access. Unsent drafts are kept when switching.
- Web Push notifications: get notified when an agent is blocked or finished, with preferences for each device.
A companion runs on your Mac, and approved devices connect over your private Tailscale network. There’s no RelayDeck cloud service or separate account to create.

Web app and PWA are available now, installed from source. Native Android and iPhone builds are in progress, with branch visibility and code-change review planned.
Repo: https://github.com/Hybridhash/relaydeck
I’d love feedback from other FastAPI developers, Contributions are welcome too—code, docs, bug reports, or ideas.
If you like the project, I’d appreciate a star! ⭐