A mobile banking app, rebuilt from scratch
We rewrote the old app in Kotlin and Swift: card ordering, transfers by phone number, SİMA sign-up for new clients.
- Client
- A bank with 30 branches
- Industry
- Banks and lenders
- Went live
- March 2025
- Duration
- 11 months
- Team
- 14 people
What was there
Another contractor had built the bank’s app in 2017. On older Android phones one launch in 20 ended in a crash, and ordering a card or moving money between your own accounts still needed a branch visit. The bank could not maintain the code: there was no documentation and every change took two to three weeks.
What we built
- Two native apps: Kotlin for Android, Swift for iOS
- Card ordering with courier delivery, card blocking and limits
- Transfers by phone number, with templates
- Identity check and account opening with SİMA for new clients
- A new API layer on Java and Kafka between the core banking system and the apps
Results
61,000 → 148,000
clients using the app every month
March 2025 to March 2026
38%
of new cards ordered in the app
Q1 2026
4.8% → 0.3%
of sessions ending in a crash
first 6 months after launch
A new version ships every two weeks and I know in advance what it brings. With the old app that was impossible.
Head of Digital Channels, a bank with 30 branches
Technologies
- Kotlin
- Swift
- Java, Spring Boot
- PostgreSQL
- Apache Kafka
- Figma
- Appium
