Happi Hacking

Writing, Systems, and Occasional Consulting

HappiHacking AB is the technical imprint of Erik "Happi" Stenman. In the Erlang and BEAM community, Happi is the name attached to the writing, books, tools, experiments, courses, and occasional advisory work.

Advisory work happens when the problem needs senior technical judgment: payment systems, BEAM runtime questions, high-throughput backends, technical leadership, agentic development workflows, or engineering work that has become hard to reason about.

Happi working as a scalable fintech backend consultant

Founder, Writer, and Systems Architect

Erik "Happi" Stenman

Former Klarna CTO. PhD in Computer Science. BEAM specialist. Author of The BEAM Book. Erik works with teams on architecture, runtime behavior, scaling, and technical leadership.

Built Klarna’s engineering organization from 1 to about 80 people during hypergrowth.
Worked on payment-system architecture and 24/7 operational scaling under real production pressure.
Advises fintech and infrastructure teams on architecture, runtime behavior, and leadership.

What Repeats in the Work

Senior judgment

Erik has worked across regulated payments, telecom-scale IoT, blockchain infrastructure, startup execution, and runtime engineering.

Direct access

Consulting work is scoped around direct access to the person doing the technical review, advice, and implementation support.

Design with delivery

Architecture decisions, project framing, and team execution stay connected, so advice can be tested against code, people, and operational constraints.

Grounded evidence

The case studies show concrete roles and systems, from Klarna and Deutsche Telekom to Laya and Sika Health.

Read Case Studies Work With Erik

About HappiHacking