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No. 020 · Other apps

lu.me

Messaging app with the core features of a popular messenger and its own look (near-black background, glass effect, background images), running on phones and in the browser.

Experiment
Period
2026-10 → 2026-11
Platforms
iOS · Android · Web
Role
Solo: design, build, ship
Tech
Fig. 1 · Chats
Fig. 2 · Chat with a photo
Fig. 3 · Group with a file

§1The problem

I wanted to find out whether I could build a real messenger alone (chats, groups, media, real time) with its own visual identity, without relying on a ready-made backend service.

§2What I built

  • Own serverHTTP API + WebSocket, SQLite database, media on disk.
  • Single appExpo / React Native (iOS, Android and web), with the screens from the design prototype.
  • MessagingReal-time chats, message receipts, sending and receiving photos, videos and files (up to 2 GB in the iPhone PWA).
  • Web extrasDrag and drop (and paste) files into a chat.
  • InvitesBy link/QR to find contacts (no phone-number login in v1).
  • Long textSplit automatically (65,536-character limit per message).
  • IdentityPer device, with the token stored only as a hash on the server; single-account mode for the beta.
  • TestsAutomated tests on the server (API and WebSocket, with a temporary database) and on the app logic.

§3The hard parts

5 entries
  1. 01

    Real-time sync with offline sending

    An outbox, receipts and a local cache that the app opens before validating the session.

  2. 02

    Large media

    Chunked, streamed upload (raw body, no multipart), with signed links (HMAC) so <img>/<video> work without an auth header.

  3. 03

    Identity designed to evolve

    “Who the user is” separated from “how they proved it”, so phone login can be added later without migrating data.

  4. 04

    Same code on three platforms

    Including real differences: blurred glass on iOS and web, a simplified version on Android; localStorage cache on the web and SQLite on the phone.

  5. 05

    iPhone PWA quirks

    Correct video duration and the photo picker.

§4Result

server tests (API and WebSocket)
25
max upload in the iPhone PWA
2 GB

The server and the web app have been live on my private network since October 2026, for a closed beta. The server has 25 API/WebSocket tests. Still missing: the installable phone build (it needs an Expo account and, on iOS, an Apple developer account) and phone-number login.

§5Stack

  • Expo / React Native (expo-router)
  • TypeScript
  • Node 24
  • Hono
  • WebSocket
  • SQLite (better-sqlite3, WAL mode)
  • Zod
  • Zustand
  • sharp
  • pm2
  • Tailscale