Open to opportunities

João Guilherme Chagas

@jooguilhermechagas

Message

I build regulated iOS banking journeys and modular apps for millions of users.

Brazil

Message

What I'm looking for

I'm open to remote roles and relocation where I can build regulated fintech products, own high-impact iOS journeys, and contribute modular architecture, production quality, and reliable release practices.

At Banco Digio, I build Open Finance data-sharing and payment journeys for a digital bank serving more than 1M users under BACEN regulation.

I designed a Swift Package Manager white-label architecture shared by Banco Digio and UberConta, enabling one codebase across banking brands and reducing new-feature delivery time by roughly 50%. I also rebuilt institution-redirect consent flows, increasing end-to-end completion from 28% to 95%.

I own production quality across Swift, Objective-C, SwiftUI, UIKit, Clean Architecture, MVVM, testing, CI/CD, and App Store releases. Using Instruments, I reduced crash rates by 20% while resolving memory and rendering issues on high-traffic screens.

Earlier, I built offline-first mobile data layers, responsive iOS interfaces, watchOS 3D experiences, and a SwiftUI drawing-recognition game. I'm a WWDC21 Swift Student Challenge winner and published author on iOS malware detection.

Experience

Work history, roles, and key accomplishments

Current

Senior iOS Engineer

Current

Datum TI

Nov 2025 - Present (9 months)

Designed a white-label modular architecture in Swift Package Manager shared across multiple banking brands, cutting time to ship new features by roughly 50%. Rebuilt Open Finance consent, data-sharing and payment journeys, raising completion from 28% to 95% and reducing crash rate by 20%.

Swift Objective C SwiftUI UIKit Combine Clean Architecture MVVM Swift Package Manager XCTest XCUITest Bitrise Fastlane Git App Store Connect TestFlight REST APIs OAuth Firebase Open Finance

Mid-Level iOS Engineer

Datum TI

Aug 2022 - Nov 2025 (3 years 3 months)

Built and maintained Open Finance data-sharing and payment features for Banco Digio and UberConta, meeting Brazilian Central Bank (BACEN) requirements. Refactored legacy screens toward MVVM and Clean Architecture, integrated RESTful APIs, and expanded XCTest coverage.

Swift Objective C SwiftUI UIKit Combine Clean Architecture MVVM XCTest XCUITest REST APIs Deep Linking CI CD Agile Jira Confluence

Junior iOS Engineer

Compass

Jan 2022 - Aug 2022 (7 months)

Implemented an offline-first data layer with Core Data and backend synchronisation, keeping the app usable under unreliable connectivity. Rebuilt UI layouts with Auto Layout and applied Apple Human Interface Guidelines.

Swift UIKit Core Data Offline First Human Interface Guidelines

iOS Developer

Apple Developer Academy @ Instituto Eldorado

Feb 2020 - Jan 2022 (1 year 11 months)

Won the WWDC21 Swift Student Challenge and shipped iOS apps with UIKit, SwiftUI, Storyboard and View Code. Built a watchOS app with SceneKit and developed a SwiftUI drawing-recognition game.

Swift UIKit SwiftUI Storyboards SceneKit Watch OS Drawing Recognition