Scale 1–5
BEAM Platform Expertise (Erlang / Elixir) 5/5
Profile
Focused on Erlang-based systems for real-time, money-critical workloads. Experience from payment platforms transfers directly to sports betting through shared constraints on event processing, settlement correctness, and continuous operation under high concurrency.
Dr. Erik Stenman is a senior systems architect with three decades of experience designing and operating distributed, fault-tolerant platforms for real-time, money-critical workloads on the BEAM. He has worked on the Erlang runtime since the late 1990s, holds a PhD on native code compilation for Erlang (the HiPE project), and wrote The BEAM Book, the technical reference on Erlang VM internals.
His work has centred on platforms where latency, correctness, and uptime directly affect financial outcomes. At Klarna he was first CTO and a core architect of the Erlang-based payment platform, running real-time credit decisioning, fraud signals, and settlement under continuous uptime as transaction volume grew by orders of magnitude. Later engagements at æternity, Deutsche Telekom, and Redcare extended the same patterns into high-throughput event pipelines and asynchronous, distributed transaction flows.
The same patterns apply across domains: real-time event streams, distributed transaction handling, retries and compensation, and continuous operation where downtime carries direct financial impact.
Recent AI work is treated as controlled engineering: traceability, auditability, and rollback in development workflows and operational tooling, not strategy.
Selected Consulting Assignments
Engagements delivered through HappiHacking AB. A selection, not exhaustive.
SEB Financing (via Brightshift)
May 2026 – Present
Engineering Lead / Senior Advisor
- Leads the technical and process scaling of Spec-Driven Development (SDD) and agentic AI-assisted software delivery within SEB Financing.
- Shapes governance-aware development workflows, compliance integration, and AI-supported specification processes for a regulated financial environment.
- Works on architecture, toolchain design, and compliance-aware development patterns, adapting SDD workflows for large-scale enterprise and SAFe-based organisations.
Kivra
Dec 2025 – Mar 2026
Advisor to the CTO (Mar 2026)
(Interim) Director of Platform Engineering (Dec 2025 – Feb 2026)
- Supported the teams behind Kivra's BEAM-heavy technical foundation, spanning architecture, reliability, and developer experience with Erlang and Elixir at the core.
- Coached engineering managers and tech leads on ownership, observability, and calmer day-to-day operations.
- Worked with the CTO on platform strategy, infrastructure modernisation, and key architectural decisions across Erlang, Elixir, Go, Kubernetes, and GCP.
Redcare Pharmacy
2024 – Present
Coach for Architects / Platform Advisor
- Works on asynchronous, event-driven transaction flows: long-running workflows, distributed state transitions, retries, and compensating actions.
- Works on reliability under load, regulatory constraints, and end-to-end observability across services.
æternity Foundation
Oct 2023 – Apr 2025
Core Team Lead (Contract, Remote)
- Returned to the æternity core team to work on backend performance and scalability of the Erlang/BEAM blockchain runtime.
- Distributed systems and fintech infrastructure focus: throughput, latency, and operational characteristics of the running chain.
Scania / TRATON Group
2023 – 2024
Chief Engineer, Offboard Platform & Connectivity
- Drove a unified vehicle-to-cloud connectivity platform across TRATON brands.
- Standardised architecture for data exchange, diagnostics, and OTA updates.
- Delivered a secure, cloud-native framework supporting future smart-fleet services.
SambaNova Systems
2022
C++ Developer, AI Compiler Infrastructure
- Worked on AI compiler and runtime infrastructure.
- Contributed to the compiler and runtime toolchain, improving efficiency and integration with PyTorch and TensorFlow.
- Technologies: Python, C++, LLVM, MLIR, PyTorch, TensorFlow.
æternity Foundation
2017 – 2019
Core Team Lead / Architect
- Designed and implemented FATE, a safer and more efficient virtual machine for smart contracts.
- Built a BEAM-based blockchain optimised for verifiable, high-throughput transactions.
- Worked across consensus, state channels, and runtime safety with a small senior team.
Employment
HappiHacking AB
2014 – Present
Founder & Director of Engineering
- Independent consultancy focused on Erlang/BEAM platforms in production: scheduler behaviour, tracing, performance tuning, observability, and runtime debugging.
- Built event pipelines on the BEAM handling 1B+ daily transactions for Deutsche Telekom, end-to-end GDPR-compliant.
- Designs AI-assisted development workflows for engineering teams, with attention to traceability, governance, and safe production use.
- Author of The BEAM Book, the technical reference on the Erlang virtual machine.
Klarna Bank AB
2005 – 2014
Chief Technology Officer → Chief Scientist
- First CTO. Scaled engineering from 1 to 80 people and established Klarna's technical foundation.
- Designed and operated the Erlang-based core payment platform: real-time credit decisioning, fraud signals, and settlement under strict latency and correctness constraints where errors translate directly into financial loss.
- Handled retries, compensation, and failure isolation across services under continuous load.
- Ran the platform under 24/7 uptime as transaction volume grew by orders of magnitude.
- Introduced fault-tolerant distributed patterns (supervision, isolation, message-passing concurrency) still in use across Klarna today.
- Worked with risk, compliance, and operations on incident response, recovery, and post-incident learning.
Virtutech AB
2004 – 2005
Senior Developer
- Optimised the Simics full-system simulator, improving performance and accuracy for enterprise clients.
Selected Projects & Achievements
- Klarna Payments Platform, an Erlang-based core that scaled from prototype to multi-country production handling millions of daily transactions, with real-time credit decisioning, fraud signals, and settlement under financial regulation.
- IoT Data Platform (Deutsche Telekom), a GDPR-compliant event pipeline on the BEAM handling 1B+ daily signals end to end.
- Blockchain Core (æternity), a BEAM-based runtime engineered for verifiable, high-throughput transactions.
- Asynchronous Case-Handling Platform (Redcare Pharmacy), guiding teams on event-driven, long-running workflows with retries, compensation, and end-to-end observability.
- The BEAM Book, the technical reference on the Erlang virtual machine.
Technical Focus
- Languages: Erlang, Elixir, Go, C / C++, Python, Rust
- BEAM Runtime: ERTS internals, scheduling, tracing, performance tuning, runtime debugging; analysis of scheduler behaviour under load, GC impact, and tracing from BEAM to OS level (perf)
- Real-time systems: event-driven flows, distributed transactions, retries and compensation, settlement correctness, latency and throughput tuning
- Payments & Risk: core payment platforms, real-time decisioning, fraud signals, regulated operations
- AI in production: controlled integration with traceability, auditability, and rollback, used in development workflows and operational tooling
- Infrastructure: Kubernetes, AWS, GCP, Terraform, Docker
- Practices: observability, continuous delivery, incident response, post-mortems
- Domains: payments, fintech, regulated platforms, IoT, blockchain
Education
PhD, Computer Science, Uppsala University (1999 – 2002) Dissertation: Native code compilation and optimisation for Erlang (HiPE project).
Licentiate, Computer Science, Uppsala University (1996 – 1999) MSc, Computer Science, Uppsala University (1992 – 1996)
Postdoc, EPFL Lausanne (2003 – 2004), working with Martin Odersky on compiler technology and early Scala development.
Publications & Speaking
- Author: The BEAM Book, the technical reference on the Erlang virtual machine.
- Speaker: Code BEAM, Erlang Workshop, fintech architecture conferences.
- Mentor: advises engineering managers and architects on sustainable, high-trust team cultures.
Contact
happi@happihacking.se happihacking.com linkedin.com/in/happi