Steven Kramer, Developer in Amsterdam, Netherlands
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Steven Kramer

Verified Expert  in Engineering

Algorithms Developer

Amsterdam, Netherlands
Toptal Member Since
November 26, 2019

Steven has extensive experience in software development with skills in a variety of technologies gained through contributions to innovative, high-quality projects. He prides himself on raising the quality of projects he's worked on and teams he's worked with. Not afraid to start projects from scratch in a greenfield setting, nor from jumping in halfway through a project to speed it up, Steven focuses on providing high-quality solutions.


SwiftUI, Model View ViewModel (MVVM), gRPC, Dependency Injection...
fashionTrade (freelance)
Xcode, Back-end, Algorithms, Agile, Mobile, Continuous Integration (CI)...
TomTom (freelance)
Back-end, Agile, iOS, Objective-C, Mobile, Objective-C++, C++, UIKit...




Preferred Environment

Amazon Web Services (AWS), C++, Objective-C, Back-end, Mobile, Swift, iOS

The most amazing...

...experience in development is getting a project in the hands of real-world users and seeing how your work is improving their life.

Work Experience

iOS and Mobile Tech Lead

2021 - PRESENT
  • Defined and implemented the initial app architecture and framework.
  • Grew the iOS team to three people and onboarded them with project architecture.
  • Delivered a POC and an MVP on an incredibly tight schedule.
  • Guided back-end and Android teams with respect to mobile API definition and implementation details.
  • Set up remote logging and observability and assisted with finding bugs in third-party hardware remotely.
  • Used and contributed to the back-end and DevSup projects (PostgreSQL, gRPC, Node.js, and Google Cloud).
Technologies: SwiftUI, Model View ViewModel (MVVM), gRPC, Dependency Injection, CI/CD Pipelines, Swift, UIKit, Unit Testing, Apple Design, MQTT, TestFlight, App Store

Tech Lead/Architect

2017 - 2019
fashionTrade (freelance)
  • Designed and implemented the proof of concept (POC) of fashionTrade's B2B fashion buying and selling app and scaled it up to commercial deployment.
  • Built the development team and grew it up to a four-person team that was in charge of screening and selecting candidates.
  • Defined the API, guided the back-end development of the API, and built smaller parts of the back end when BE team was time-constrained.
  • Assisted the PM in defining the product and was actively contributing features and UX.
  • Built automated deployment tools of the app for testing and production, which were used as the basis for the CI pipeline.
Technologies: Xcode, Back-end, Algorithms, Agile, Mobile, Continuous Integration (CI), Cloud Computing, REST, iOS, Swift, APIs, UIKit, Model View ViewModel (MVVM), Unit Testing, UI Testing, REST APIs, WebSockets, Apple Design, TestFlight, App Store

Senior Mobile Engineer Navigation App

2009 - 2017
TomTom (freelance)
  • Improved the iPhone-specific UX and the C++ integration; guided and trained the development team to improve their skills in these fields.
  • Did the heavy-lifting for supporting iOS in TomTom's C++ platform; ported all the software to 64 bit when Apple started mandating this.
  • Handled the most complex issues found in the field, e.g., when iOS introduced a bug that caused the app to crash after a few hours of use.
  • Fixed the Java-inspired basic app architecture, which was not optimal for iOS, saving the team huge amounts of time spent "working against the grain."
  • Introduced support for right-to-left (i.e., Arabic) script in the app.
  • Contributed to CI, distribution, and other tooling required to maintain and deploy the app.
  • Contributed to hiring and screening candidates, interviewing and appraising CVs.
  • Contributed to product management and product definition groups.
  • Served as the technical point of contact for Apple developer support.
Technologies: Back-end, Agile, iOS, Objective-C, Mobile, Objective-C++, C++, UIKit, Unit Testing, UI Testing, REST APIs, Apple Design, TestFlight, App Store

Mobile Lead and Architect

2011 - 2013
TomTom Taxi (freelance)
  • Kick-started the mobile app development for TomTom Taxi; took on lead and architect roles until commercial release.
  • Worked with the PM to define functionality and UX; implemented initial versions.
  • Implemented the POC for the Taxi app running on Android.
  • Guided the back-end team in designing and implementing the REST API.
Technologies: Xcode, Back-end, Agile, Mobile, REST, iOS, Objective-C, APIs, UIKit, Unit Testing, REST APIs, Apple Design, TestFlight, App Store

Team Lead, iOS

2009 - 2009
Ahold (freelance)
  • Served as the team lead and architect for the initial launch of the signature app of the Netherlands' largest retailer.
  • Helped to define the product's functionality and UX.
  • Defined the client-server API from a mobile perspective.
  • Contributed to building and scaling up the team (up to 5 devs, screening, interviewing, team organization).
  • Contributed to securing the app and the API (passing the external audit on the first attempt).
Technologies: Xcode, Agile, Mobile, Security, REST, Objective-C, iOS, APIs, UIKit, Unit Testing, REST APIs, App Store

Architect, Team Lead

2005 - 2009
ImBeeld/Cammit (freelance)
  • Helped the MT to decide between build or buy of a security camera management solution and started the building phase.
  • Grew the tech team (+4 people) and trained the team to learn key skills for the project.
  • Built and implemented the entire service offering (front end, back end, and mobile).
  • Integrated with third-party components (camera API, SMS gateway, and ERP).
  • Architected and built streaming pipelines, receiving from the camera and multiplexing the streams to several clients.
  • Designed and built a distributed video storage./retrieval/management stack.
  • Researched and built an image processing pipeline for motion detection to trigger alarm events for our users.
Technologies: Xcode, Back-end, Algorithms, C++, Perl, Back-end Performance, iOS, Objective-C, Mobile, PostgreSQL, Full-stack, Security, Video Streaming, REST APIs

Kernel Developer

2004 - 2004
TomTom (freelance)
  • Worked on drivers (USB) and kernel (suspend and resume) for the custom hardware of TomTom's first portable navigation device during its RTM and go-to-market phase.
Technologies: Windows Kernel Drivers, Linux, Kernel, C, C++

Development Manager

1999 - 2002
  • Managed the 16 person engineering team that developed licensable cross-platform (Linux, macOS, and Windows) C++ frameworks for rich multimedia rendering and complex UIs, and bespoke solutions built on those frameworks.
  • Oversaw the development of the completely automated playout solution for the country's best-ranking FM radio station.
  • Maintained the frameworks and radio applications and expanded on them to add digital streaming over the public internet and DVB for broadcast networks (freelance).
  • Created an application for automated playout of broadcast music TV, based on QuickTime for video decompression plus rendering to the (Blackmagic) broadcast video hardware, and CoreImage for configurable transitions between clips and adverts (freelance).
  • Managed the developer support and documentation team.
Technologies: Algorithms, Objective-C, Performance, Image Processing, Streaming, DVB-S, MPEG, User Interface (UI), C++

Tom Tom Navigation App
TomTom's satnav app for iOS was the first turn-by-turn navigation app in the App Store and was wildly successful in its first few years. I worked on two versions of the app, which were largely independent of each other, over the course of a few years. I contributed key parts to the app, being part of a larger team. I trained and guided team members in some complex areas where knowledge was lacking in the company's existing teams.

Greenfield Mobile Project for Large Scale B2B Wholesaling

The platform offered (amongst much more) a trading solution for fashion wholesale buyers and sellers. I was asked to build the MVP of the mobile app and afterward to scale the project and the team for production. The app was accounted for the bigger part of the company's turnover immediately when it became available. We fine-tuned the UX for maximum productivity on the limited screen sizes and network inherent in mobile.

Taxi Rider App

I bootstrapped mobile apps (iOS and Android) for a service that linked customers with taxi drivers. The app interfaced with a back-end and an on-dash device in the taxi to support the entire customer journey, from choosing the destination and pick-up point to driver selection, payments, route calculation, and time and cost estimates.

I designed and implemented the initial versions of the apps, expanded the mobile development team, and together we delivered the app to the App Store successfully. I took part in the APIs and back-end design architecture and supported the UX designers to use the correct mobile-specific design patterns.


Swift, Objective-C, C, C++, Perl, SQL, Java, JavaScript, TypeScript


UIKit, AppKit, Combine, SwiftUI, gRPC


Core Graphics, REST APIs, Core Animation, OpenGL, OpenGL ES


Xcode, Auto Layout, TestFlight, Git, GitHub, MQTT, Shell, Jira, Subversion (SVN)


iOS, Mobile, Kernel, Android, Amazon Web Services (AWS), Docker, MacOS, Unix, Linux, Firebase


Objective-C++, User Interface (UI), Debugging, Greenfield, Optimization, Performance Analysis, Performance Tuning, Apple Design, App Store, Security, Image Processing, Streaming, Performance, Client-server Model, Scripting, Videos, Concurrency, Concurrent Computing, Multithreading, Video Streaming, Audio Streaming, Back-end Performance, TCP/IP, Network Protocols, Scalability, Systems, Version Control Systems, Distributed Systems, Distributed Software, Algorithms, APIs, WebSockets, Web Servers, Full-stack, Cloud Computing, MPEG, DVB-S, Windows Kernel Drivers, Machine Learning, AVFoundation, Back-end, Ajax, TV Broadcasting, Radio, Astrophysics, CI/CD Pipelines, UI Testing


REST, Distributed Computing, Agile, Design Patterns, Functional Reactive Programming, Unit Testing, DevOps, Continuous Integration (CI), VIPER Architecture, Functional Programming, Model View ViewModel (MVVM), Dependency Injection


Databases, PostgreSQL, JSON

1990 - 1997

Master's Degree in Astrophysics

University of Amsterdam - Amsterdam, Netherlands

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