Tadej Slamic, Developer in Oslo, Norway

Tadej Slamic

Software Developer

Oslo, Norway
Toptal Member Since
July 10, 2019

With over a decade in the software industry, Tadej has helped startups launch their first product, assisted FTSE 100 enterprises with digital transformation, been a part of the fintech boom, and helped particle accelerators cool down. He loves creating scalable back ends and is an expert in crafting modern and performant mobile, web, and desktop apps.

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Go, Java, JavaScript, TypeScript, Python, GraphQL, Android, iOS, React...
Team Management, Technical Leadership, Leadership, Tech Sales, Public Speaking
Python, Node.js, React, TypeScript, Swift, Kotlin, Java, Docker, Kubernetes...


Oslo, Norway



Preferred Environment

Unix, JetBrains, Git

The most amazing...

...project I've worked on went from zero to millions of users in a span of a year and won an internationally acclaimed award for the best app in its genre.

Work Experience

2020 - PRESENT

Principal Consultant

  • Helped a fintech startup deliver an MVP, leading to a successful series A round and winning the award for the non-bank lender of the year.
  • Assisted a multinational pharmaceutical and biotechnology corporation with software streamlining the delivery of the COVID-19 vaccine.
  • Deployed numerous smart contracts to the Ethereum blockchain for a well-funded crypto startup with a current market cap of $7M and more than 50,000 transactions.
Technologies: Go, Java, JavaScript, TypeScript, Python, GraphQL, Android, iOS, React, React Native, PostgreSQL, Firebase, Kubernetes, Terraform, Amazon Web Services (AWS), Google Cloud, Experian, Amazon Cognito, Node.js, Plaid, Stripe, Fiserv, Ethereum, Web3.js
2019 - 2022

Chief Technology Officer

  • Oversaw the engineering efforts and delivery, aligning tech strategy with company OKRs, ensuring modern practices, processes and tools were in place. Assisted leaders in other offices (Sweden, Denmark, Romania, Ukraine) adopt a similar MO.
  • Managed the technical hiring. Conducted 150+ technical interviews since joining.
  • Assisted with acquisitions, technical due diligence, and sales, resulting in an increase in monthly revenue and hourly rates across the engineering team.
Technologies: Team Management, Technical Leadership, Leadership, Tech Sales, Public Speaking
2018 - 2019

Technical Lead

  • Helped architect and develop an identity provider (IDP) for a multinational supermarket chain. We reduced the running cost, eliminated all legacy issues, and improved latency, crash reporting, and metrics. Used by 2 million people regularly.
  • Led the development of the app (Android and iOS) and back end for Scandinavia's largest haircut provider. Consolidating multiple services onto a single platform with a fluid API and scale. This helped the company expand across Europe with ease.
  • Held accountable for the technical output of teams working on Norway's most popular apps.
Technologies: Python, Node.js, React, TypeScript, Swift, Kotlin, Java, Docker, Kubernetes, Google Cloud Platform (GCP), gRPC, Go, Technical Leadership, Technical Hiring, Leadership, Team Leadership, Team Management, Interviews, Interviewing, Mobile, Mobile APIs, Mobile Apps, Cloud, Google, Amazon Web Services (AWS), Heroku, Code Review, Open Source, Source Code Review, Presentations, Tech Sales, CTO
2017 - 2018

Engineering Lead

Lloyds Banking Group
  • Led a team of 10+ people responsible for the platinum journeys around payments and statements on the #1 UK banking app three years in a row.
  • Governed the adaption of a recent mobile acquisition onto our tech stack.
  • Engaged in technical debt burning, architecture, refactoring, and performance tuning of an app used by millions.
  • Performed code reviews across the whole mobile floor.
Technologies: Jenkins, Gerrit, Behavior-driven Development (BDD), JavaScript, iOS, Android, Kotlin, Java, Interviews, Technical Hiring, Interviewing, Code Review, Open Source, Source Code Review, Team Management, Distributed Team Management, Offshore Team Management, Cucumber, Leadership, Agile, Mobile Banking, Online Banking, Fintech, Architecture, Web Architecture
2016 - 2017

Senior Software Consultant

  • Acted as a technical architect for a major health care client to investigate how their web product can be transferred onto mobile platforms. Following my report, the client implemented the proposed solution.
  • Worked as the Android lead for the UK's largest postal service—leading the development of an app providing insight into employee operations, environment, and patterns that improved delivery predictions.
  • Reviewed an Android app of the largest UK-owned airport operator—resolving many memory/performance issues and bugs.
Technologies: Xamarin, C#, JavaScript, iOS, Android, Kotlin, Code Review, Web, Interviews, Agile, Amazon Web Services (AWS), Python, Team Management
2013 - 2016

Senior Software Engineer

Full Tilt Poker / PokerStars
  • Spearheaded the full development lifecycle of the Full Tilt Poker Android app. Over a million downloads across multiple distribution systems in less than a year.
  • Achieved the IGA gaming app award for the Best Poker App of 2014.
  • Built parts of the app 2-20x faster. Introduced form-factor independent UI components with a notable increase in tablet use afterward.
Technologies: C, C++, JavaScript, iOS, Android, Leadership
2013 - 2013

Software Engineer

Simplifydigital (now part of Currys)
  • Collaborated with the team creating the UK's first-ever energy switching app.
  • Helped decide the tech stack, design, coding guidelines, and CI/CD.
  • Involved in the API and database design and creation.
Technologies: C#, Android, Agile
2012 - 2013

Software Engineer

Comtrade Group
  • Converted a hybrid app to a native Android app resulting in a noticeably improved performance, robustness, and look and feel.
  • Efficiently collaborated with teams across various geographic locations.
Technologies: JavaScript, Cordova, PhoneGap, iOS, Objective-C, Android, Java
2011 - 2012

Software Engineer

  • Implemented APIs and server-side features for various websites and portals.
  • Created a Facebook clone for an Italian poker community.
  • Developed an app displaying sports betting information across TV screens.
Technologies: PHP, MooTools, Kohana, jQuery, Swing, Java, Django, Python
2010 - 2010


Deutsches Elektronen-Synchrotron (DESY)
  • Worked as a member of the Cryogenic Control Lab.
  • Helped develop a plugin for a particle accelerator control system responsible for monitoring the temperature and cooling procedures.
Technologies: Eclipse RCP, Eclipse, SWT, Java


Learn Kotlin/Native

Learn Kotlin/Native is a set of tutorials I created after many talks and presentations I did around the topic. Designed to get your feet wet, it helps you get started and finishes with an example of how to write code running on both Android and iOS.

Open Source Projects

I’ve created many useful (and less useful) open-source projects across multiple technologies, ranging from gRPC, Go, golden files, dependency injection, cross-platform tools, tutorials, scripts, and more.

Lloyds Bank Mobile Banking

Lloyds Bank mobile app is used by over 8 million people daily. It was the #1 UK banking app for three years in a row, according to Forrester. I was leading a team of 10+ people creating platinum journeys involving payments and statements.

Technical Writing

I've written a series of blog posts about building and securing an imaginary API for a restaurant. The blogs showcase established practices in authentication and authorization, using Java, Spring Boot, and Auth0.



Java, Go, Kotlin, Python, TypeScript, JavaScript, C#, HTML5, SQL, Swift, Objective-C, HTML, CSS, XML, YAML, Solidity, Ruby, Embedded C, C, C++, PHP, Bash, GraphQL


Spring Boot, Spring, OAuth 2, JSON Web Tokens (JWT), Flask, Flutter, Express.js, gRPC, Swagger, .NET, Ruby on Rails (RoR), Angular, Bootstrap, Kohana, PhoneGap, Django, Swing, React Native, Storm, Hadoop, Spark


Experian, Yodlee API Interface, REST APIs, Node.js, API Development, Slack API, Stripe, RxJava 2, OpenID, MooTools, SWT, jQuery, React, Eclipse SWT, Stripe API, Facebook API, GitHub API, Twitter API, Google Places API, Google Play API, Web3.js


Firebase Cloud Messaging (FCM), Git, Make, IntelliJ, GitHub, Auth0, Google Analytics, Gradle, Apache Maven, Fastlane, Terraform, IntelliJ IDEA, Android Studio, Xcode, Gerrit, JetBrains, Shell, Jenkins, Sonar, Eclipse RCP, Cucumber, Jira, Visual Studio App Center, Amazon Cognito, Plaid


Automation, App Development, RESTful Development, REST, Clean Architecture, Scalable Application, Dependency Injection, Agile, Functional Programming, Microservices, Reactive Programming, Continuous Delivery (CD), Continuous Integration (CI), Event-driven Architecture, Test-driven Development (TDD), Unit Testing, Web Architecture, Web Application Architecture, Serverless Architecture, Continuous Deployment, Behavior-driven Development (BDD), Cross-platform, Testing, MapReduce, DevOps


AWS Lambda, Mobile, Android, Firebase, Google Cloud Platform (GCP), Twilio, iOS, Xamarin, Docker, Amazon Web Services (AWS), Ethereum, Azure, Kubernetes, Eclipse, Apache Kafka, Unix, Blockchain, Heroku, Web


JSON, PostgreSQL, Memcached, Databases, NoSQL, Redis, Realm, MySQL, Cloud Firestore, Google Cloud, Elasticsearch, PL/SQL, MongoDB

Industry Expertise

Banking & Finance


Software Development, Blockchain Development, Back-end, APIs, Authentication, Technology, Technical Leadership, SOAP, Minimum Viable Product (MVP), Mobile Architecture, Middleware, Software as a Service (SaaS), CTO, Fintech, Mobile Apps, Mobile APIs, Containerization, Containers, Software Architecture, Writing & Editing, Stripe Payments, Planning, Back-end Development, Firebase Cloud Functions, Data Scraping, Payment APIs, SOLID Principles, Open Source, Communication, Leadership, Architecture, Web Scraping, Mentorship & Coaching, Native Mobile Apps, Web Development, Full-stack, Team Management, Distributed Team Management, Technical Hiring, Interviews, Interviewing, Code Review, Source Code Review, Push Notifications, Scripting, SaaS, API Integration, Integration Testing, System Integration Testing (SIT), OAuth, CI/CD Pipelines, System Architecture, Progressive Web Applications (PWA), Cloud Services, Consul, Financial Services, WebSockets, FindBugs, Google Cloud Functions, Cloud, Serverless, Protocol Buffers, Algorithms, Data Structures, Analytics, User Experience (UX), Concurrency, Trading, Mathematics, Software, Cordova, Kotlin/Native, Mobile Banking, Machine Learning, Big Data, Offshore Team Management, Online Banking, Team Leadership, Google, Presentations, Tech Sales, Public Speaking, Technical Writing, Fiserv


2007 - 2010

Completed Credits towards a Bachelor's Degree in Mathematics and Computer Science

University of Ljubljana - Ljubljana, Slovenia