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 ➔
Fisher
.NET event store and document database on SQLite. The full Critter Stack experience in a database that lives inside your own process - no server to install or provision.
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 ➔
Bobcat
Author, supervise, and run integration tests in .NET. Executable specifications that read as requirements, built straight from an Event Model, with big suites split across worker processes and flakiness reported honestly.
Documentation ➔
JasperFx (Shared Libraries)
Common utilities and infrastructure shared across the Critter Stack ecosystem.
Documentation ➔Commercial Products
CritterWatch
From dev-time insight to production control for Wolverine, Marten, and Polecat - for you and your AI agents.
Pick the plan that fits your scale.
Community
- Maximum ServicesUnlimited
- Alerts-
- Audit Logs-
- Custom Thresholds-
- MultiTenancy-
- Operations-
- License Needed-
Professional
- Maximum Services25
- Alerts✓
- Audit Logs✓
- Custom Thresholds✓
- MultiTenancy✓
- Operations✓
- License Needed✓
Enterprise
- Maximum ServicesUnlimited
- Alerts✓
- Audit Logs✓
- Custom Thresholds✓
- MultiTenancy✓
- Operations✓
- License Needed✓
You can request a trial license to evaluate CritterWatch before you buy.
Stoat
ForthcomingThe design-time surface for Critter Stack development - the model, the work it implies, and the evidence that closes it.
Draw your system as an Event Model, turn it into work your AI agents can claim, keep what they learn between sessions, and watch the Bobcat test runs that say the work is done - one host, one browser tab.
The Event Model as a document
Slices, chapters, hotspots and the specs bound to them, assembled from your running application and your specs and drawn on one canvas.
Work as a cross-repo plan
A graph of GitHub issues, NuGet publishes and test-run gates across repositories. Stoat derives what is ready - nobody maintains a status column.
Agents park, they don't poll
AI agents wait on upstream dependencies and package publishes over MCP without burning tokens in a loop.
Memory that outlives the session
What one agent session learned, the next one recalls - scoped to a session, a repository or everything, with full-text and semantic search.
The run board
Every Bobcat suite on the box, live - steps streaming, retries and flakiness reported honestly, with CTRF and JUnit exports for CI.
Stoat is a work in progress and not yet generally available. When it ships, Stoat will be bundled with every paid CritterWatch license at no additional cost.
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.
💬 Have questions about our commercial products? Contact us and we'll be happy to help.
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