ClickNBack

What is ClickNBack

Mon, 01 Dec 2025 00:00:00 +0100

ClickNBack is a cashback platform built end-to-end as a real product: a native iOS app backed by a custom REST API, both developed and maintained by a single engineer.

The backend is deployed and running in production. The iOS app is in active development.

The platform covers standard cashback flows — authentication, offer browsing, and transaction tracking — but the goal is not to demonstrate features in isolation. The goal is to show how a product behaves as a system: how the client and backend co-evolve, how data flows across layers, how failures are handled, and how the codebase sustains itself as complexity grows.

iOS Mobile App

Sat, 01 Nov 2025 00:00:00 +0100

The iOS app is built with SwiftUI and modern Swift concurrency (async/await), and is currently in active development. It is designed from the start with production standards in mind, not as a prototype.

Architecture

The app follows a modular MVVM + Clean Architecture structure, with explicit separation between:

Presentation layer (SwiftUI views and ViewModels)
Domain layer (use cases, business logic, models)
Data layer (network client, repositories, caching)

Each module has a clearly defined responsibility and can be developed and tested independently. This structure is not over-engineered — it reflects the minimum necessary to keep the codebase navigable and stable as new features are added.

Backend System

Wed, 01 Oct 2025 00:00:00 +0100

The backend is built with Python and FastAPI, and is currently deployed and running in production on a Linux VPS. It is not a local prototype — it handles real requests, manages persistent data, and is updated through a CI/CD pipeline.

Core features

REST API with typed request and response schemas, versioned endpoints, and explicit error contracts
JWT-based authentication with token refresh, expiration handling, and rotation
PostgreSQL database with SQLAlchemy ORM, using atomic transactions to maintain data consistency
Background jobs for asynchronous cashback reward processing
Internal event-driven communication for decoupled domain flows

Infrastructure

End-to-End Approach

Mon, 01 Sep 2025 00:00:00 +0100

Most engineers specialize in one side of the stack. Backend engineers design APIs without full visibility into how mobile clients consume them. iOS engineers implement features without understanding the constraints of the services they depend on.

The result is often friction: API contracts that don’t match client needs, workarounds in the app to compensate for server behavior, and slow iteration cycles when changes are needed on both sides simultaneously.

Building both sides changes the dynamic

Engineering Focus

Fri, 01 Aug 2025 00:00:00 +0100

The engineering priorities of this project reflect what matters most in production environments.

Correctness over happy paths

Features are built to behave correctly across failure cases — authentication token expiration, network errors mid-flow, partial backend responses, empty states. The goal is to handle these situations gracefully rather than assuming everything goes as planned. Users in production don’t follow the happy path.

Testability as a structural constraint

The architecture is designed to be testable by default. This is not a post-hoc concern — it shapes how the code is structured from the beginning.

Source Code

Tue, 01 Jul 2025 00:00:00 +0100

Both the iOS app and the backend are open source and available on GitHub:

iOS App: https://github.com/jerosanchez/clicknback-ios
Backend: https://github.com/jerosanchez/clicknback

What you will find

The repositories are structured the way I structure real-world projects — not as a showcase of isolated patterns, but as codebases that reflect actual engineering decisions.

iOS App

Feature modules with MVVM + Clean Architecture layering
Swift Package Manager for dependency management
Networking layer with typed request/response handling and JWT authentication
XCTest-based test suite covering ViewModels, domain logic, and networking

Backend

App Store (Upcoming)

Sun, 01 Jun 2025 00:00:00 +0100

The iOS app is being prepared for distribution through TestFlight and the App Store. Distribution is not an afterthought — the project is structured for it from the start.

Environment management

The app uses separate schemes and configurations for development, staging, and production environments, managing:

API base URLs per environment
Feature flags and logging levels
Build and bundle identifiers

This ensures that development builds never talk to production data, and that release builds are configured correctly without manual intervention.

About

Wed, 01 Jan 2025 00:00:00 +0100

I’m Jero Sánchez, a senior iOS engineer with 7+ years of experience building native applications, and an additional year focused on backend systems.

Most of my career has been in product-focused companies where the iOS app is a core part of the business. The most significant was Cabify — a leading ride-hailing platform in Spain and Latin America, with millions of users and over a million daily transactions — where I worked on a high-traffic iOS app as part of a cross-functional product team.

Credits

Wed, 01 Jan 2025 00:00:00 +0100

Credits for the images used in this site:

Chevron icon created by Cursor Creative - Flaticon
iOS image: iOS icon created by Picons - Flaticon
Backend system: Online server icons created by ALTOP7 - Flaticon
End-to-end image: End to end icons created by Creative Avenue - Flaticon
Engineering focus: Technology icons created by Freepik - Flaticon
Repositories: Github icons created by Freepik - Flaticon
App distribution: App icons created by Freepik - Flaticon
About: User icons created by Freepik - Flaticon