Software Engineering
Systems design / Architecture
Scalability, Reliability, High Availability
Boaty McBoatface
Distributed Ledgers

Tobias Lindahl

Consultant, Happi Hacking AB


Tobias is a senior software developer and systems architect with an extensive experience with building and maintaining large-scale systems with high demands on availability and reliability.

A problem solver at heart, Tobias is happiest when faced with complex problems. He is a firm believer in that most situations can be solved by truly understanding the problem at hand and finding the appropriate way of modelling the problem.

While Erlang is his go to language for development, his skills at analyzing problems and finding solutions can be applied to most backend development.

During his years at the High Performance Erlang (HiPE) research group at Uppsala University he was the original developer of Dialyzer, a static analysis tool for Erlang that now is an industry standard tool for finding bugs in Erlang programs. Dialyzer is distributed in the Erlang/OTP distribution.


2014 - now Senior Software Developer, Happi Hacking

See below for project descriptions.

Keywords: Scalability, Availability, Reliability, Fault tolerance.

Technologies: Erlang, Flutter, Dart, Javascript, Docker, Linux, Bash, AWS, GIT, Ansible.

2008 - 2014 Senior Software Developer, Klarna Bank AB

Tobias worked on all aspects of the main transaction system. He was a developer, architect and a member of Klarna's Technical Advisory Board. In the later years, he was mostly focused on growing the capacity of the system in the face of exponential growth of the transaction volume.

Keywords: Scalability, Availability, Reliability, Fault tolerance, FinTech.

Technologies: Erlang, Linux, Bash, GIT

Projects in HappiHacking (by selection)

2022 Developer for AI Startup in stealth mode

Analyzing ML models in MLIR and llvm.

Keywords: ML, AI, Compiler Technology

Technologies: C++

2022 IOT & Digital Twins for Deutsche Telekom

Tobias joined the testing team for a Happi Hacking project done for Deutche Telekom. The system is a large IoT central hub with large external and internal APIs. Tobias used stateful property based testing to validate the microservices' interoperability.

Keywords: Property Based Testing, APIs, Microservices

Technologies: Erlang, Linux, Bash, GIT, Quickcheck, AWS.

2021 MQTT broker development for EMQ

Tobias was a part of the core development team for the MQTT message broker EMQX. He implemented the functionality for persistent MQTT sessions.

Keywords: MQTT, IoT, Message Brokers

Technologies: Erlang, Linux, Bash, GIT, MQTT, EMQX.

2021 - now Building the mobile game Taba

Tobias, together with other HappiHacking staff, developed the casual puzzle game Taba, scheduled to be released during spring 2023. Tobias wrote the backend in Erlang, and also several versions of the front end, using Javascript, Dart and Flutter.

Keywords: Casual Games, API design, UI programming.

Technologies: Erlang, Javascript, Dart, Linux, Bash, GIT, AWS, Flutter, Postgres

2019 - 2020 Data pipeline for IoT communication for Deutsche Telekom

Tobias built a data pipeline from scratch for handling a large volume of IoT communication. The implementation was in Erlang, and was a proof of concept for later projects made for Deutche Telekom.

Keywords: IoT, Data Pipelines, APIs, Microservices

Technologies: Erlang, Linux, Bash, GIT, Quickcheck, AWS.

2017 - 2019 Building a blockchain for æternity

Tobias joined an international team that from scratch developed the public block chain æternity. He implemented some core features such as the Patricia Merkle Tree and the block verification and construction. While Tobias these days thinks that proof of work is bad in general, a lot of the cryptographic techniques are very interesting for other areas in the form of distributed ledgers.

Keywords: Blockchain, Merkle Trees, Distributed Ledgers, Virtual Machines, Compilers.

Technologies: Erlang, Linux, Bash, GIT.

2015 - 2020 Building a real estate platform for Doorling

Tobias was originally the only backend developer in a project that evolved into a company called Doorling. The platform was a social media platform that intended to democratize the real estate market. This was a joint effort with the Norwegian real estate company Krogsveen.

Keywords: Backend API design, DynamoDB, AWS, Real Estate Market.

Technologies: Erlang, Linux, Bash, GIT, Ansible, AWS.

2014 - 2017 Building the online board game platform

The company built, an online board game platform that is now discontinued.

Keywords: API design, Distributed databases, UI programming, Platform design.

Technologies: Erlang, Javascript, Linux, Bash, GIT, Ansible, AWS.


2002 - 2008 PhD Student, Uppsala University/Ericsson

Stumbling at the end, Tobias never defended his PhD thesis, but the time at the HiPE research group yielded Dialyzer, a static analysis tool for finding bugs in Erlang programs. And a bunch of academic publications.

Keywords: Static Analysis, Compilers, Virtual Machines, Research, Academic Writing.

Technologies: Erlang, Bash, Linux

1996 - 2001 MSc Engineering Physics, Uppsala University

Keywords: Physics, Computer Science, Engineering.

Master’s programme during which Tobias specialized in algorithms, compiler techniques and static analysis of Erlang programs.