OneCard
Fintech mobile app for iOS and Android. Core contributor to the OneCard 2.0 rewrite, base architecture, and the New Architecture (TurboModules, JSI) migration.
10M+ downloads
650K+ DAUs
React NativeTypeScriptNew ArchitectureTurboModulesJSI
Hi, I'm
Sankalp Singh
Senior Software Engineer
Five years building mobile products that went from an early startup to millions of users. I care about the details people notice, the performance they don't, and the engineering decisions that keep things from falling apart as a product grows. I like the parts of engineering where a good architectural call quietly saves someone else a bad afternoon three months from now. When I'm not thinking about how to make a product better, I'm probably watching a football match and wondering why the manager made that substitution.
~/sankalp
$ cat facts.txt
01 // Shipped
Apps I've Shipped
OneScore
Fintech mobile app for iOS and Android, part of the same product ecosystem as OneCard.
100M+ downloads
40M+ users
React NativeTypeScript
02 // Open Source
Open Source
react-native-network-tools
A developer tooling library for real-time network request inspection and analytics in bare/Expo React Native apps, for both Android (OkHttp interceptor) and iOS (NSURLProtocol).
React Native core — text clipping fix
Diagnosed and fixed an Android text clipping bug in React Native core (ReactTextView.java) where adjustsFontSizeToFit failed to recalculate font size on container resize.
03 // <SkillList />
Skills
Rendered the way I'd build it — flick the list and watch the runtime work.
Drag · flick · pull to refresh
Mobile
- React Native
- New Architecture
- TurboModules
- JSI
- Fabric
- Hermes
- Expo
- iOS
- Android
Languages
- TypeScript
- JavaScript
- Kotlin
- Java
- Swift
- SQL
- C++
- HTML/CSS
State & Data
- Zustand
- TanStack Query
- Zod
- RESTful
- Web Socket
AI Tools
- Pi Agent
- Claude Code
- OpenSpec
- Graphify
- Kiro
- Codex
Tooling
- VS Code
- Xcode
- Android Studio
- Charles Proxy
- Mockoon
- react-devtools
- Storybook
Testing
- Jest
- RNTL
- Maestro
- fast-check
CI/CD & Build
- GitHub Actions
- Fastlane
- Build Pipelines
- GitLab Runner
Backend
- Node.js
- Express
- MongoDB
- Firebase
Integrations
- Razorpay
- Juspay
- Zeta
- PayU
- Firebase
- Amplitude
- AppsFlyer
- Google Maps
04 // AI Workflow
How I build with AI
Ask away — the answers are mine, written ahead of time.
What do you care about most when building a product?
The stuff users feel, even when they don't know why. A screen that responds instantly, a flow that doesn't make them think, a feature that doesn't fall apart when traffic grows. I like working on the layer where product decisions and engineering decisions meet.
What's your approach to performance?
I don't like optimising things just because a profiler says I can. I want to know what the user is actually feeling first. Then I trace it back to the real bottleneck, whether that's rendering, network calls, native communication, or architecture.
What was one of your more interesting engineering problems?
Moving a large React Native app from the old bridge to the New Architecture. It wasn't just a migration exercise. It meant understanding how JS and native communicate, finding the places where the old assumptions mattered, and making sure the user actually benefited from the change.
How do you think about architecture?
I try to make the next engineer's job easier. A good architectural decision isn't necessarily the cleverest one. It's the one that makes the codebase easier to change six months later, when nobody remembers why that decision was made.
Do you use AI to write code?
Absolutely. But I don't want it deciding what we're building. I use AI to explore a codebase, challenge an approach, implement well-defined pieces, and run through verification. The important thinking still happens before the prompt.
What's something you enjoy building?
Anything where the interaction matters. Gestures, animations, navigation, real-time data, things that have to feel right at 60fps. I'm probably more interested in the last 10% of polish than I should be.
What do you do when you're not coding?
Watch football and analyse matches far more seriously than my friends think is reasonable. I enjoy the tactical side of the game almost as much as watching it.
05 // Writing
Technical Writing
Latest posts, pulled live from Medium.
06 // Contact
Let's Connect
Always happy to talk React Native, mobile architecture, or whatever you're building.