Lammert Westerhoff
Verified Expert in Engineering
Full-stack Developer
Lammert is a full-stack developer with an entrepreneurial mindset specializing in iOS development. Due to collaboration with clients such as the Dutch railways, ING, and Eneco, his work has reached millions of people. Additionally, he is experienced with Java, Kotlin, and React Native and has extensive knowledge of AWS. As a certified scrum master, Lammert has also led teams on several projects.
Portfolio
Experience
Availability
Preferred Environment
Amazon Web Services (AWS), Slack, IntelliJ IDEA, Xcode, MacOS
The most amazing...
...project I've developed was an app for Dutch railways, one of the most used apps in the Netherlands that won the award for the best transportation app.
Work Experience
CTO and Full-stack Developer
Fifty Fifty Card
- Developed a native iOS and Android app with Kotlin Multiplatform Mobile (KMM) that allows users to sign up and make reservations at restaurants.
- Created a scalable server with Kotlin and Ktor running on AWS Elastic Beanstalk and Postgres database.
- Contributed to the design of user experience and mobile app from the ground up.
- Created a second mobile app for restaurant managers and staff to manage reservations and restaurants.
iOS and Android Developer
Evervault Limited
- Developed an iOS and Android SDK to encrypt data with the Evervault platform.
- Created a secure Inputs library using SwiftUI for iOS and Compose for Android to process and encrypt credit card information.
- Integrated a Rust library with the iOS and Android SDKs to create a secure connection to Evervault servers.
Lead Mobile Developer
MiRus
- Developed a KMM app for iOS and Android for patient monitoring. The app connects to a wristband through Bluetooth to collect activity information, present this information in the app, and show feedback from doctors.
- Acted as the lead developer by introducing, instructing, and guiding Android developers on KMM development.
- Developed a KMM app for surgical planning. Surgeons can use the app to approve surgical plans by inspecting Digital Imaging and Communications in Medicine (DICOM) files and chatting with planners to approve or decline plans.
- Created a KMM framework to manage network requests, cache, and view models.
Freelance iOS Developer
Eneco
- Developed a new Eneco native iOS app using KMM and Swift.
- Launched the app eight months after the project started and attracted hundreds of thousands of users.
- Created a tool to manage localization and strings in one place for both iOS and Android.
Full-stack Developer Consultant
Dutch Railways
- Developed the NS app for iOS which was used by millions of people.
- Developed and managed several REST API services in Kotlin and ran them on AWS.
- Developed and launched the NS International app targeted to international travelers.
Senior Developer
Nyon (now Fashion Cloud)
- Completely migrated the Nyon OrderWriter iPad app from Objective-C to Swift.
- Created a server-side ordering pipeline for fashion retailers to manage their orders.
- Established the hiring process for new developers and coached junior developers.
Senior Software Developer Consultant
ING Netherlands
- Developer the ING Beleggen (Trading) apps for iOS and Android using React Native.
- Introduced a model-view-viewmodel (MVVM) architecture into the app.
- Introduced a new design review process between developers and designers.
Software Developer Consultant
Xebia
- Consulted for four big clients of Xebia, namely XS4All, ING (twice), Wehkamp, and Dutch Railways.
- Initiated and organize dthe first Dutch AngularJS Conference: NG-NL.
- Created a conference app and CMS for Xebia's conferences.
- Initiated and organized the first Xebia School Students Innovation Day.
- Completed the Certified Scrum Master training by the Scrum Alliance.
Co-founder and Senior Full-stack Developer
Stylbar
- Developed an app where users could share photos of a particular outfit to get fashion advice from friends, family, and expert stylists.
- Built a full-stack small social network on AWS with a native iOS app using Java.
- Brainstormed with other co-founders to create a business plan, pitch deck, and initial feature set for the app.
Senior Software Developer
Infor
- Successfully led several Scrum teams as tech lead and scrum master.
- Worked within Infor's first mobile team and launched several iOS apps to customers.
- Created a mobile platform and gave worldwide training to other Infor employees.
Software Engineer
Asset Control (now Alveo)
- Created several financial data loaders of financial data vendors under which the Bloomberg data loader.
- Developed a platform for loading financial data instruments for various vendors.
- Completed the training for Scrum team members and helped introduce Scrum into asset control processes.
Experience
Eneco Energy App for iOS
https://apps.apple.com/lu/app/eneco/id827734058NS Travel Planner App for iOS
https://apps.apple.com/us/app/ns-travel-planner/id370362301NS International iPhone App
https://apps.apple.com/us/app/ns-international/id886645737ING Investing - Beleggen App for iOS and Android
https://apps.apple.com/nl/app/ing-beleggen/id1231921275Health Tracking and Patient Monitoring App
https://apps.apple.com/us/app/miruspatient/id1585381100Fifty Fifty Card for iOS and Android
https://fiftyfiftycard.mxFifty Fifty Serve for iOS and Android
https://fiftyfiftycard.mxSkillset
Languages
Java, Swift, Kotlin, Objective-C, JavaScript, SQL, Python, TypeScript, C++
Frameworks
iOS SDK, SwiftUI, Android SDK, React Native, AngularJS, Spring, Django, .NET, Core Location, Ktor
Libraries/APIs
REST APIs, Node.js, React, Stripe, Stripe API
Tools
Xcode, GitHub, Slack, Figma, IntelliJ IDEA, Composer
Paradigms
Agile Software Development, Scrum, DevOps, Clean Architecture
Platforms
iOS, Firebase, Mobile, MacOS, Amazon Web Services (AWS), Android, Bluetooth LE
Other
Web Services, Scrum Master, Kotlin Multiplatform Mobile (KMM), Mobile Architecture, Technical Leadership, Architecture, Location Services, Accessibility, Back-end, Mobile App Development, Full-stack, Bluetooth, GPS, Serverless, Encryption, Startups, Images, MERN Stack, Data Encryption, Infor
Industry Expertise
Healthcare
Storage
MongoDB, Databases, PostgreSQL
Education
Bachelor's Degree in Computer Science
Hanze University Groningen - Groningen, The Netherlands
Certifications
Certified Scrum Master
Scrum Alliance
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