Our Products
The Critter Stack — Open Source
The Critter Stack is a suite of open source .NET libraries for building server-side applications with Event Sourcing, CQRS, document storage, and asynchronous messaging. JasperFx Software offers consulting services and support plans for all of these tools.
Marten
Transactional document database and event store built on PostgreSQL. The most full-featured Event Sourcing library on .NET.
Documentation ➔
Wolverine
Next-generation command bus, message bus, and mediator for .NET. Powerful asynchronous messaging with minimal ceremony.
Documentation ➔
Polecat
.NET event store and document database on SQL Server 2025. Bringing the Critter Stack experience to SQL Server.
Documentation ➔
Weasel
Database schema management for PostgreSQL, SQL Server, and SQLite.
Documentation ➔
Alba
Fast and expressive integration testing for ASP.NET Core web services.
Documentation ➔
JasperFx (Shared Libraries)
Common utilities and infrastructure shared across the Critter Stack ecosystem.
Documentation ➔Commercial Products
Commercial tools that extend the Critter Stack with production monitoring, AI-assisted development, and advanced capabilities.
CritterWatch
Operational insight and observability for systems built on the Critter Stack. Production monitoring, management, and diagnostics.
Documentation ➔MCP Extensions
Model Context Protocol extensions for integrating Critter Stack tools with AI-assisted development environments.
Learn more ➔Marten Extensions
PostGIS and PgVector extensions for Marten — add geospatial queries and vector search to your PostgreSQL-backed applications.
Learn more ➔CritterStack AI Skills
AI-powered development accelerators for the Critter Stack — speed up your workflow with intelligent code assistance. Annual licenses; pick the tier that fits your team size.
🐛 Found a bug or have a feature request? Report and track issues for CritterWatch, the AI Skills, and our other commercial products in our public ProductSupport issue tracker on GitHub.
Why the Critter Stack?
Low friction development for faster delivery
The best tooling on .NET for Event Sourcing and CQRS architectures
Optimized for AI-assisted development workflows
Testable, resilient, and observable by design
Battle-hardened and thoroughly documented — proven in production
Code that fits in your head — less ceremony, more clarity
See the Critter Stack in Action
Multi-Tenancy in the Critter Stack
Event Sourcing and CQRS with the Critter Stack
Vertical Slices the Critter Stack Way