SLAP 🫸

The sticker pack platform for WhatsApp — discover, create, and share animated sticker packs.

Slap is a community-driven Android app where creators upload sticker packs and users can browse, save, and export them directly to WhatsApp. Built with a modern TypeScript monorepo — Expo on the client, Elysia on the server, Cloudflare R2 for storage, and Redis for trending feeds.

• Discover — Browse trending and new sticker packs with a masonry-style grid feed
• Search — Full-text search across pack names, tags, and categories
• Pack detail — Preview all stickers in a pack; copy individual stickers to clipboard, share to WhatsApp, or save to gallery
• WhatsApp export — One-tap export of a full sticker pack to WhatsApp via react-native-wa-stickers-animated
• Upload — Creators can upload packs of up to 30 stickers (any image format; server converts to WebP at ≤1.5 MB, max 1024 × 1024)
• Vault (Saves) — Bookmark packs for quick access later
• Profile — Public creator profiles with avatar, bio, and published packs
• Trending — Redis-cached trending algorithm based on downloads and saves
• Auth — Email OTP (Resend) and Discord OAuth via Better Auth

slap/
├── apps/
│   ├── native/          # Expo Android app
│   │   ├── app/         # Expo Router screens (file-based routing)
│   │   │   ├── (auth)/  # Auth screens (email OTP, Discord)
│   │   │   ├── (tabs)/  # Main tabs: Discover, Upload, Vault, Profile
│   │   │   ├── pack/    # Pack detail screen [id].tsx
│   │   │   └── user/    # Public user profile [userId].tsx
│   │   ├── components/  # Shared UI components
│   │   └── utils/       # sticker-actions, download, whatsapp helpers
│   └── server/          # Elysia HTTP server
├── packages/
│   ├── api/             # oRPC routers, image processing, queues, storage
│   ├── auth/            # Better Auth configuration
│   ├── db/              # Prisma schema + generated client
│   ├── env/             # Type-safe env validation (@t3-oss/env-core)
│   └── config/          # Shared TypeScript / Biome configs
└── nx.json

• Bun ≥ 1.1 — bun.sh
• Node ≥ 20 (for Expo CLI tooling)
• Android Studio + Android SDK (API 33+)
• PostgreSQL 15+ running locally (or remote)
• Redis 7+ running locally
• Cloudflare R2 bucket with public URL enabled
• Resend account for email OTP
• Discord OAuth app (optional — needed for Discord login)

git clone https://github.com/your-org/slap.git
cd slap
bun install

cp apps/server/.env.example apps/server/.env

cd packages/db
bunx prisma db push

# Optional: seed with sample data
bun run seed

cd apps/server
bun run dev
# Server starts on http://localhost:3000

cd apps/native
bunx expo run:android

Make sure an Android emulator is running or a physical device is connected via ADB.

Android App (Expo)
      │
      │  oRPC (type-safe HTTP)
      ▼
Elysia Server (Bun)
      │
      ├── Better Auth     ──► PostgreSQL (users, sessions)
      ├── oRPC Routers    ──► PostgreSQL (packs, stickers, saves, tags)
      ├── BullMQ Worker   ──► Redis (image-process queue)
      │        │
      │        └──► Sharp (WebP conversion, resize ≤1024px, ≤1.5MB)
      └── Trending Worker ──► Redis (pre-computed trending pack IDs)
                │
                └──► Cloudflare R2 (WebP sticker storage)
                           │
                           └──► Public CDN URL (served directly to app)

Sticker upload flow:

1. User selects up to 30 images (any format) in the Upload tab
2. Files are sent to the server as multipart form data via oRPC
3. Server enqueues each sticker into BullMQ (image-process queue)
4. Worker converts to WebP (Sharp), resizes to ≤1024px, compresses to ≤1.5MB
5. WebP is uploaded to Cloudflare R2; public URL stored in PostgreSQL
6. Pack status flips to READY once all stickers are processed

Trending feed flow:

1. Every download and save increments counters on the pack row
2. A BullMQ worker (trending-recalc) periodically scores packs and writes ordered IDs to Redis (slap:trending:cache)
3. The Discover feed reads from cache; falls back to ORDER BY downloads DESC on cache miss

The backend exposes a type-safe oRPC API. All routes are defined in packages/api/src/routers/.

appRouter
├── healthCheck
├── checkEmail
├── packs         list · get · search · create · trending
├── stickers      upload
├── saves         save · unsave · list
├── download      trackDownload
├── tags          list
├── categories    list
└── profile       get · update · packs

Public procedures require no authentication. Protected procedures require a valid Better Auth session cookie.

1. Fork the repo and create a branch: git checkout -b feat/your-feature
2. Follow conventional commits: feat:, fix:, refactor:, docs:, chore:
3. Run the formatter before committing: bunx biome check --write .
4. Open a PR describing the change and link any related issues

• iOS support
• Animated sticker packs (WEBP/APNG/Lottie)
• Creator analytics dashboard
• Pack collections and playlists
• In-app sticker search with visual similarity
• Push notifications for new packs from followed creators
• Deployment: Cloudflare Workers (server) + managed PostgreSQL

All rights reserved. Not open for public use at this time.