GiBud

How it fits together

How it flows

1. 1

   Browse

   App · Web

   Home, categories and search load from /api/v1. The app keeps categories cached in SQLite, so they open instantly.

2. 2

   Bid

   Ably

   A bid is placed through the API, and the new price, bid history and countdown update live on every open screen.

3. 3

   Add to cart

   API

   Won auctions and Buy Now items collect in the buyer's cart.

4. 4

   Check out

   Prisma

   One database transaction turns the cart into purchases and snapshots each item's title and image, so the order stays accurate.

5. 5

   After the sale

   Web · Chat

   The sale appears in the seller's "My sales", where they generate an invoice. Buyer and seller can chat about delivery.

My contribution

1. 01Built the GiBud mobile app alone in Flutter for iOS and Android: sign-in, home and categories, search, item pages, bidding, cart, checkout, chat, selling and a "My GiBud" area for bids, listings, purchases and sales.
2. 02Live auctions on the phone: prices, bid history and countdowns update in real time over Ably on item screens and in "My active bids".
3. 03App architecture: BLoC for state, get_it for dependency injection, go_router for navigation, typed DTOs generated with json_serializable, and a token store for authenticated API calls.
4. 04Categories cached on the device in SQLite, and data refreshed automatically when the app comes back to the foreground.
5. 05Selling from the phone: pick photos from the camera or gallery and upload them with a new listing.
6. 06Built versioned REST endpoints for the mobile app: auction items by category, item details, placing bids and bid history, a user's active bids and own listings, cart, checkout and purchases.
7. 07Checkout that turns a cart into purchases inside a single Prisma transaction, snapshotting each item's title and image so orders stay accurate after listings change, then clearing the cart.
8. 08Item listing flow with categories and media stored on Cloudflare R2 through its S3-compatible API.
9. 09Invoice designer on the "My sales" page: sellers pick sales, set the customer, currency and tax, and generate an invoice.
10. 10Chat API routes plus an Ably token endpoint for real-time direct messages.
11. 11Evolved the Prisma schema with migrations and seed data as features landed.
12. 12Followed the codebase's architecture: thin API routes, repositories that own validation and business logic, request IDs and structured logging to Sentry.

Challenges I solved

1. 01Bids change constantly, and a stale price on a phone means someone loses an auction.

   Solution · Item screens and "My bids" subscribe to Ably channels, so the price, bid list and countdown update live. Data also refreshes when the app comes back to the foreground.

2. 02Checkout touches several tables. A failure halfway would leave a cart half-bought.

   Solution · Placing an order runs in one Prisma transaction: it creates the purchases, saves each item's title and image, and clears the cart, or it does nothing at all.

3. 03Categories load on almost every screen but rarely change.

   Solution · The app caches them on the device in SQLite, so the home screen opens instantly, even on a slow connection.

4. 04One developer, one app, a long feature list.

   Solution · A strict structure (data repositories, one BLoC per screen, get_it for dependencies, go_router for navigation, generated JSON models) kept 200+ files easy to work in.

What I learned

• ✦Owning a whole mobile app alone, from the first commit to checkout.
• ✦Designing an API from the client's side: what the phone needs, in as few calls as possible.
• ✦Real-time systems: pushing changes to the app instead of asking the server again and again.
• ✦Using transactions and saved snapshots for anything that involves money.