In this episode of the Elixir Mentor Podcast, I talk with Tjaco Oostdijk, a drummer turned Elixir developer now working at DPG Media, one of the largest media companies in the Netherlands. Tjaco played drums professionally from the age of seven and has taught for 22 years, before landing in software through a music distribution company writing Ruby and eventually moving to Elixir nearly a decade ago.

We get into what it takes to keep Elixir running inside a large enterprise. DPG adopted Elixir after a high-traffic Ruby service fell over at scale, and Tjaco describes the reality of working in a locked-down environment standardized on Kotlin, using Copilot with Anthropic models while waiting for Claude Code to be approved. He also talks about the colleagues who stay skeptical of AI tooling and why that skepticism can be healthy.

The heart of the conversation is muziekles.app, the application Tjaco built for Dutch music teachers to run their entire teaching practice, from year-long scheduling and student accounts to homework and assignments. He explains why he deliberately keeps payments out of the product, how he thinks about onboarding teachers, and the build process using Phoenix, Ash, Claude Code, and Tidewave. We also compare notes on shipping side projects fast, multi-tenancy in Ash, and the differences between hardware and software work.

If you are building with Elixir inside a company that hasn't standardized on it, or shipping a side project with AI tooling, this conversation is full of practical, hard-won lessons from someone doing both at once.

Connect with Tjaco:
- Website:https://drumusician.com
- X / Twitter:https://x.com/drumusician
- GitHub:https://github.com/drumusician
- LinkedIn:https://www.linkedin.com/in/tjaco-oostdijk

Resources Mentioned:
- muziekles.app:https://muziekles.app
- Tidewave:https://tidewave.ai
- Vocablo:https://vocabloapp.com
- Kabisa:https://kabisa.nl

Sponsors:
- BEAMOps:https://beamops.co.uk
- Paraxial.io:https://paraxial.io

SUPPORT ELIXIR MENTOR
- Elixir Mentor:https://elixirmentor.com