Alex Koutmos on Elixir for Finance, Trading & Blockchain

<p>Brex runs on Elixir. Klarna runs on Erlang. Mastercard is believed to use it. And most of the community that builds on these systems watches them with PromEx - a library written by today&#39;s guest.</p><p>Alex Koutmos has been in the Elixir ecosystem for over a decade. He wrote PromEx - the Prometheus metrics library most of this audience runs in production - and he&#39;s just written Elixir for Finance with his brother Dimitrios, a tenured finance professor at Texas A&amp;M. The book takes Livebook, Explorer, NX, and Scholar and points them straight at markets, trading strategies, and blockchain infrastructure.</p><p>Topics include:</p><ul><li><p>why switching money and routing a stock order are the same problem as switching a phone call - and why the BEAM was built for both</p></li><li><p>the ISO 8583 protocol story: 100 lines of C per message frame, dropped to 10 in pure Erlang, dropped to 4 with the bit syntax - and why nobody talks about this</p></li><li><p>Explorer as an Elixir wrapper around Polars (a Rust data frame library) - why the BEAM delegates the heavy compute and keeps the orchestration</p></li><li><p>how to use Livebook, NX, and Scholar to backtest a moving average crossover trading strategy without leaving Elixir</p></li><li><p>why &quot;let it crash&quot; doesn&#39;t mean &quot;let the money vanish&quot; - and exactly how a ledger, Oban, and durable event storage keep the truth safe across process restarts</p></li><li><p>the difference between a ledger and a database - and why a bank built on plain Postgres misses the point</p></li><li><p>blockchain as a distributed ledger: the same distributed state problem the BEAM community was chewing on long before Bitcoin existed</p></li><li><p>why fintech companies use Erlang and Elixir as a competitive advantage - and tell nobody</p></li><li><p>BlockScout, Aeternity, and where BEAM languages already run in blockchain infrastructure</p></li><li><p>what the Python and JVM financial tooling stacks miss that Explorer and NX cover - and where they still win</p></li></ul><p>Recorded August/September 2026.</p><p><strong>Resources mentioned:</strong></p><ul><li><p>Elixir for Finance - the book</p></li><li><p>PromEx on Hex</p></li><li><p>BlockScout - open source Ethereum explorer written in Elixir</p></li><li><p>Aeternity - blockchain built in Erlang</p></li></ul>