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Martín Zangl

@martnzangl

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Senior Android Engineer at Checkout.com who shipped a payment SDK and raised Swift Medical’s crash-free users to 99.6%.

Spain

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What I'm looking for

My contract at Checkout.com has completed, and I’m available immediately. I’m looking for roles in Spain or with remote-first European teams.

At Checkout.com, I worked on the Payment Flow SDK and merchant integration tooling across Android, iOS and React Native. I published a Kotlin and Jetpack Compose sample app, implemented native SDK changes to complete two React Native releases, and moved payment component spacing into the public styling API.

At Swift Medical, I rebuilt the offline-first app’s synchronization queue in Room, preserving document order while leaving WorkManager to execute the work. Documents that had sat on devices for months synchronized, and the number of Worker instances came down.

I profiled long-session crashes with Android Profiler and Perfetto, then moved the paths users hit most from RxJava to Coroutines and rebuilt some screens in Jetpack Compose. Across a full working session, memory use fell by about 24%, CPU by about 33%, and crash-free users settled at 99.6%.

At PayPal and Mercado Libre, I delivered credit and payment journeys, strengthened end-to-end testing, and built reusable Android components. I’m at my best when a production problem that looks like a bug turns out to be an architecture problem; I’m based in Valencia and available immediately for roles in Spain or remote-first European teams.

Experience

Work history, roles, and key accomplishments

Senior Android Engineer

Checkout.com

Nov 2025 - Jul 2026 (8 months)

Worked on the Payment Flow SDK and merchant integration tooling across Android, iOS, and React Native. Published the public sample app, implemented co-branded card scheme support, and wrote a Gradle plugin for API key management.

Kotlin Jetpack Compose Android SDK Swift IOS SDK React Native TypeScript Gradle

Payment SDKs

Card Payment

Senior Android Engineer

Swift Medical

Mar 2023 - Oct 2025 (2 years 7 months)

Owned reliability and feature work on an offline-first wound-care app, rebuilding the sync queue in Room and migrating key paths off RxJava. Improved crash-free users from 70% to 99.6% and supported native Android and iOS in the Flutter successor.

Kotlin Java Android SDK Coroutines Flow RxJava MVVM MVP Clean Architecture Dagger ROOM Realm WorkManager Flutter Dart Swift Objective C OpenCV TensorFlow

Android Profiler

Perfetto

Gitlab CI Junit MockK Espresso FHIR

Senior Android Engineer

PayPal

Nov 2021 - Jan 2023 (1 year 2 months)

Worked on Savings and Credits UK within PayPal Wallet's modular architecture. Restructured flows onto MVVM and unidirectional data flow, built an end-to-end test library, and delivered complete credit flows across Android, iOS, and Java backend.

Kotlin Java Android SDK Android Jetpack Coroutines

DI Dagger Hilt

MVVM

UDF

Junit Espresso Page Object Model Jenkins SonarQube JaCoCo Splunk Postman

Senior Android Engineer

Mercado Libre

Apr 2020 - Nov 2021 (1 year 7 months)

Built payment and installment flows for the virtual credit card, working from product and customer journey to API contracts. Created an SDK for resource handling and defined metrics for middle-end performance and business measures.

Kotlin Java Android SDK Jetpack Coroutines

FLEX (Internal UDF Framework)

Server Driven UIs Swift Datadog New Relic

Senior Android Engineer

Santex

May 2015 - Apr 2020 (4 years 11 months)

Led Android development across four domains including an IoT e-bike platform and a contribution to Zynga's Words with Friends. Set up automated builds, owned code review and conventions, and ran an internal RxJava workshop.

Android Java Kotlin Jetpack Flutter Dart React Native React JavaScript Swift Objective C Firebase Jenkins CircleCi

Semi-Senior Android Engineer

Globant

May 2014 - May 2015 (1 year)

Delivered Android work for BBVA and JPMorgan Chase, including a conference-room booking app and migration of a legacy web mobile app to native Android using MVP. Contributed to JPMorgan's internal application store.

Android Java Dagger Apache Cordova Jenkins SVN Git Jira

Android Engineer

Taller Technologies

Mar 2013 - May 2014 (1 year 2 months)

Built Android components for Intel's Context Aware middleware SDK and implemented a real-time electronic price tag client over XMPP. Set up CI for the Android project.

Android Java JavaScript NodeJS XMPP SQLite Junit Jenkins Bamboo

Software Developer

Freelance

Sep 2005 - Mar 2010 (4 years 6 months)

Built custom software for small businesses while studying, including Java Swing desktop applications and an IoT taximeter with Arduino and Android client.

Java Java EE Java Swing C Android MySQL SQLite Arduino