Looking for a job

Jan-Hendrik de Vaal

@jhdevaal

I'm a Senior Android/KMP engineer (15+ yrs) building award-winning mobile products — e-commerce, edutainment, IoT. Open to remote contract work.

South Africa

Message

What I'm looking for

I'm looking for remote Android or Kotlin Multiplatform work — freelance/contract or full-time — where I own meaningful pieces of the product, not just tickets. I'm motivated by real technical challenges: device integrations, streaming, architecture problems that reward careful engineering over busywork. Based in Cape Town (SAST, UTC+2), overlapping well with US and European hours.

My path into Android started over 15 years ago, and since then I've worked across e-commerce, edutainment, and IoT/Bluetooth LE devices — usually owning a product end to end rather than just a slice of it.

Most recently I've been at Combustion Inc., a US smart-cooking device company, as sole Android engineer: shipping new BLE and Wi-Fi-enabled devices end-to-end (UI, device communication, cloud sync), and authoring roughly 60% of Combustion's open-source Android BLE framework — the device layer behind both the production app and the public SDK used for third-party integrations. Before that, I rebuilt the Noggin app for Paramount's preschool edutainment service (2M+ lifetime subscribers), winning Best Branded Learning App at the 2024 Kidscreen Awards, and built its video streaming and Chromecast experience across phone, tablet, and Android TV. Earlier, I led a small Android team at Flat Circle across IoT, fintech, media, and logistics clients, and built the mobile site that won Best eCommerce Mobile Site at SA's eCommerce Awards while at Takealot.

I hold an MSc in Applied Mathematics (cum laude) from Stellenbosch University, and I'm part of Toptal's top-3% freelance network.

Outside client work, I build my own Kotlin Multiplatform projects for fun — including a first-person dungeon crawler and a retro PC game collection tracker — as a way to push KMP and Compose Multiplatform further than day-to-day client work usually allows.

I'm open to both freelance contracts and full-time roles, and most interested in work where the technical challenge is real and the craft is taken seriously.

Experience

Work history, roles, and key accomplishments

Current

Senior Android Engineer

Current

Combustion Inc.

Jun 2024 - Present (2 years 3 months)

Integrated new smart devices into the app, extended to Wi-Fi, authored over 60% of the open-source BLE framework, and overhauled UI and data layer.

Kotlin IoT Coroutines Jetpack Compose Ktor ROOM Dagger Bluetooth Bluetooth Low Energy Flow Android Studio Android SDK

Current

Android Engineer

Current

Toptal

Feb 2021 - Present (5 years 7 months)

A global, exclusive freelancing platform for the top 3% of talent.

Senior Android Engineer

Noggin Paramount

Feb 2021 - Jul 2024 (3 years 5 months)

Rebuilt the Noggin app on a team selected from the original engineers, winning Best Learning App. Built video streaming and Chromecast casting. Decommissioned the app on a small team selected again from the original engineers, delivering a brand-neutral build for resale.

Kotlin Android Streaming Flow Android TV

Senior Android Developer

Teamwork

Aug 2020 - Jan 2021 (5 months)

Rewrote the Teamwork project management app as a native Android app on a small team.

Kotlin Android Android SDK Android Architecture Android Jetpack RxJava Dagger Retrofit

Lead Android Engineer

Flat Circle

Apr 2016 - Jul 2020 (4 years 3 months)

Delivered production apps on schedule for clients spanning IoT, fintech, media, and logistics. Managed a team of up to three Android developers, owning code reviews and technical decisions across every project.

Kotlin Android Android SDK Android Studio Java IoT GraphQL Retrofit RxJava Android TV

Senior Android Developer

Media 24

Jul 2015 - Mar 2016 (8 months)

Owned the app end to end as sole Android developer — architecture, implementation, and optimization. Shipped a month ahead of schedule, getting the app live in time to capture Black Friday’s download and conversion peak.

Android Android SDK Android Studio Java Retrofit RxJava Ecommerce

Senior Mobile Developer

Takealot Group

Dec 2013 - Jun 2015 (1 year 6 months)

Overhauled Takealot’s outdated, outsourced Android app — now consistently rated in the top 5 (in South Africa) for shopping on the Play Store. Built the new mobile site as part of a two-person team, winning the Best eCommerce Mobile Site Award at SA’s eCommerce Awards 2015.

Ecommerce Android Android SDK Android Studio Java IoT GraphQL Retrofit RxJava Android TV

Senior Software Developer

Virtual Mobile Technologies

Apr 2010 - Nov 2011 (1 year 7 months)

Built and maintained the VMs that compiled Ramp’s platform-agnostic app definitions into native code for Android, iOS, Windows Phone, BlackBerry, and Java ME — early cross-platform engineering, years ahead of tools like Kotlin Multiplatform.

Android Java IoT iOS Blackberry C#

Senior Software Developer

Perceive

Jan 2007 - Mar 2010 (3 years 2 months)

Engineered the surveillance system’s monitor application and its detection algorithms, including human and fall detection.

Python

Education

Degrees, certifications, and relevant coursework

Stellenbosch University

Bachelor of Science with Honours (BScHons), Computer Science

Stellenbosch University

Bachelor of Science (BSc) in Mathematical Science , Mathematical Science

Stellenbosch University

Master of Science in Engineering, Applied Mathematics

Grade: cum laude

Master of Science in Engineering in Applied Mathematics, cum laude. Thesis on metric reconstruction of multiple rigid bodies using structure from motion.