About

I'm Erik Shafer, a backend software engineer and consultant based in Nebraska.

I start with Event Modeling and Domain-Driven Design, write down what we learn as a spec (Specification-Driven Development, or SDD), and build event-driven systems where they fit: event sourcing, CQRS, and messaging. For AI-assisted work I use Evaluation-Driven Development (EDD), with the evals written first.

Most of that work is in .NET, with some on the JVM and Node when the team uses them.

I'm a Senior Consultant at Improving and a member of the JasperFx core team, which builds the Critter Stack. The open-source libraries are Marten (a document database and event store on PostgreSQL), Polecat (the same on SQL Server), Wolverine (messaging and HTTP), and Alba (integration testing). CritterWatch, JasperFx's commercial console, monitors and operates them in production.

I speak at conferences and user groups, most recently at KCDC 2026 (Kansas City Developer Conference). The full list is on the Speaking page.

The blog has my posts, including every one from my earlier site, event-sourcing.dev. Nothing has been deleted. It's in the name.

Contact

The best way to reach me is the contact form. If you'd rather use your own mail client, I'm at erik@appendonly.net.

• GitHub
• Bluesky
• X / Twitter
• LinkedIn
• YouTube