Firsty: Global Travel eSIM App

The Problem

The Firsty team had a strong business idea: sell affordable eSIM data plans directly to travelers, cutting out roaming fees and physical SIM cards. What they did not have was a mobile app.

The challenge was significant. The app needed to serve travelers across 190 countries in 12 languages, handle real-time carrier plan availability, generate QR codes for eSIM activation, and process payments securely — all in a single codebase that worked identically on iOS and Android.

What I Built

I built the entire app in Flutter, targeting both iOS and Android from a single codebase. The core feature was a real-time carrier switching engine that pulled live plan availability from the backend and let users browse, select, and activate eSIM plans in minutes.

Key technical decisions included using Firebase Realtime Database for live plan status updates, integrating Stripe for payment processing, and implementing QR code generation so users could activate their eSIM directly from the app without manual configuration.

The 12-language localization system was built to support right-to-left languages alongside standard LTR, without any layout breaks. Fastlane handled automated builds and App Store submissions, reducing deployment time to under 20 minutes.

The Result

Firsty hit 100,000 downloads within the first year of launch and maintains a 4.9 star rating on the App Store. The app is actively used across 190 countries, with users consistently praising the activation flow for being the simplest in the market.

The cross-platform approach saved the client the cost of two separate native teams. A single Flutter codebase serves both iOS and Android users with identical features and performance.

Tech Stack