Sergio Sastre Florez

DevOps Engineer

Munich, Bavaria, Germany11 yrs 11 mos experience
Highly Stable

Key Highlights

  • Official Google Developer Expert for Android.
  • Authored popular Android open-source libraries.
  • Mentored over 80 Android developers on testing.
Stackforce AI infers this person is a Fintech and Logistics-focused Android Developer with a strong emphasis on software quality.

Contact

Skills

Core Skills

AndroidSoftware Quality

Other Skills

Extreme ProgrammingPair/Mob-ProgrammingTDDSoftware DesignIntegration TestingSnapshot TestingMutation TestingProperty-based TestingHigh Quality StandardsSoftware ArchitectureMobile DevicesiOS DesignJavaREST

About

Official Google Developer Expert (GDE) for Android with 12+ years of experience, currently consulting for Deutsche Bahn Systel. I've worked at companies well known in Germany like Check24, Lieferando, AutoScout24, and Hermes Germany. Passionate about software quality, I’ve not only written numerous blog posts on testing, but I‘ve also given many tech-talks at big conferences on that matter and I am actively contributing to the Android development community. I’ve also authored popular Android open-source libraries, including ComposablePreviewScanner (150K+ monthly downloads), which is also integrated in Roborazzi. Furthermore, my repository Android Screenshot Testing Playground earned a Google Open Source Peer Bonus award in 2024. My commitment to software quality extends from open source to industry, where I help build reliable, scalable, and maintainable Android apps. 📈Quality always first. 🪄I make things happen.

Experience

11 yrs 11 mos
Total Experience
1 yr 11 mos
Average Tenure
--
Current Experience

Deutsche bahn

2 roles

Android & DevOps Engineer (extern)

Jan 2026Present · 3 mos

Android Engineer (extern)

Aug 2023Dec 2025 · 2 yrs 4 mos

Hermes germany gmbh

Android Engineer (extern)

Jan 2022May 2023 · 1 yr 4 mos · Hamburg, Germany · Remote

  • Further development of the navigation app Hermes couriers use to deliver parcels in Germany.
  • Use of Extreme Programming (XP) practices on a daily basis to deliver high quality software:
  • Pair/Mob-Programming
  • TDD
  • Our team successfully conducted a huge migration of the map SDK on time thanks to XP practices
Extreme ProgrammingPair/Mob-ProgrammingTDDAndroidSoftware Quality

Appdev

Lead Android Engineer

Jun 2021Oct 2025 · 4 yrs 4 mos · Munich, Bavaria, Germany

  • Working as external consultant for
  • Autoscout24
  • Hermes
  • Deutsche Bahn
  • As well as a couple of appDev’s in-house projects

Autoscout24

Android Engineer (extern)

Jun 2021Dec 2021 · 6 mos · Munich, Bavaria, Germany · Hybrid

  • Led the redesign of the search screen, the most used screen in the app.
  • Successfully owned and executed the integration of the leasing feature into the same search screen, delivering it before a tight deadline without known bugs.
  • Our team was the first to finish this feature at such high quality standard.

Check24 vergleichsportal

Android Engineer

Feb 2016Jun 2021 · 5 yrs 4 mos · Munich y alrededores, Alemania

  • Conception and development of the CHECK24 Android app with focus on financial products like MoneyTracker multi-banking product, as well as C24Bank.
  • Also worked on other Check24 products like Versicherungscenter and Legal Insurance.
  • Accomplishments:
  • Successfully led the migration of the money-tracker app architecture to web sockets with the introduction of new PSD2 law for banking apps. As a result, we were the first multi-banking app in Germany to successfully implement PSD2, ahead of our competition.
  • Actively fostering the importance of testing to create high quality apps.
  • At MoneyTracker, we had 3 week release-cycles. In nearly 4,5 years we only needed 3 hot fixes.
  • Testing:
  • Full introduction of Integration testing in several projects, also in the form of Snapshot tests.
  • Creation of tools to facilitate writing Snapshot tests with specific user settings.
  • Mitigation of flakyness in integration tests as well as reducing its build times through techniques like "test sharding" and "mocked server apis"
  • Introduction to new testing concepts such as "mutation testing" and "property-based testing".
  • Training:
  • Active mentoring of newcomers.
  • Actively coaching over 80 Android developers company-wise mainly on topics around testing through inhouse tech-talks and training sessions.
Integration TestingSnapshot TestingMutation TestingProperty-based TestingAndroidSoftware Quality

Bredex gmbh

Software Developer

Jan 2015Jan 2016 · 1 yr · Braunschweig y alrededores, Alemania

  • Development of Android applications for in-house projects as well as a consultant

Just eat takeaway.com

Android developer

Mar 2014Dec 2014 · 9 mos · Braunschweig y alrededores, Alemania

  • Further development of the Pizza.de Android app and its optimisation to adapt its design to tablets.
  • It originally belonged to Pizza.de GmbH and was acquired by Lieferando (German branch from Takeaway.com)

Fraunhofer iese (institute for experimental software engineering)

Software Engineer (Master Project)

Oct 2012Jan 2013 · 3 mos · Kaiserslautern, Germany

  • Project for John Deer in an international team of 8 people
  • Use of informal agile methodologies
  • Extension of an existing iOS app to run on a brand-new tractor device.
  • Search of the most suitable technology able to run on that device
  • UI design and development in that technology: JavaFX. Use of CSS
  • Assistance for the connection between frontend and backend

Katho

ASP.NET and C# Developer

Mar 2011Jun 2011 · 3 mos · Kortrijk, Belgium

  • Project for the uni website, international team of 5 people
  • Web Development : use of ASP.NET , C# , JavaScript and CSS tech.
  • Development of SQL procedures

Education

UPM and Technische Universität Kaiserslautern

Software Engineer — European Master on Software Engineering

Jan 2011Jan 2013

Universidad de Valladolid

Ingeniero técnico en informática de sistemas — Ingeniería informática

Jan 2006Jan 2011

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