About Slicekit
A SaaS foundation you would have built anyway
Every new SaaS starts with weeks of the same plumbing: authentication, a typed client, background jobs, logging, dashboards, CI. Slicekit is that plumbing, assembled, wired together and tested, so the first thing you write is your product.
Design principles
Every decision in Slicekit follows a small set of principles. They are the reason the architecture looks the way it does and the reason you can hand it to a new engineer on day one.
One architecture, both sides
The API and the SPA follow the same vertical-slice shape. Learn one feature and you can navigate every feature, on either side of the wire.
Batteries included, not bolted on
Auth, audit, messaging, storage and observability are first-class parts of the template, not afterthoughts you wire up under deadline pressure.
Readable over clever
Explicit handlers, named events and obvious folders. The code is written to be read by the next engineer, or the next agent, six months from now.
Yours to own
Buy once and the code is yours under a commercial license: standard tooling, no proprietary runtime. Rename it, rip parts out, deploy anywhere. There is no platform to depend on.
What's in the box
A modern, mainstream stack with no exotic dependencies, chosen so the knowledge transfers to your other projects, and so hiring against it is easy.
- API
- .NET 10 · Minimal API · Wolverine CQRS · EF Core · PostgreSQL
- Frontend
- Vite · React 19 · TypeScript · TanStack Router & Query · shadcn/ui · Tailwind v4
- Messaging & storage
- RabbitMQ · Redis · MinIO (S3) · transactional outbox
- Billing
- Stripe subscriptions · Checkout & Customer Portal · webhooks · feature-key entitlements
- Observability
- OpenTelemetry · Loki · Tempo · Prometheus · Grafana · Alertmanager
- Tooling
- Docker Compose · GitHub Actions · Testcontainers · architecture tests
Gerwin Kuijntjes
Certified Software Engineer
- Engineer-architected
- Human-reviewed
- Tested & typed
Why I built Slicekit
I'm Gerwin, a certified software engineer. On project after project I rebuilt the same foundation: authentication, an audited admin, observability, the typed client between an API and its UI. And the moment one went to production in the EU (where I live), it had to satisfy GDPR (data export, deletion, consent), so that got built too. And the moment it had to make money, subscription billing (Stripe, free trials, plan entitlements) was the next thing to rebuild, so that is in the box too. Every time, the first month went to plumbing instead of the product.
Slicekit is the foundation I wish I'd had. The decisions are made, the hard parts are solved, and the boring 80% is already shipped, with tens of hours of optimization on top to get the defaults, the performance and the developer experience right. You start on the 20% that is actually your product.
Every line is verified, not just written. Architecture tests enforce the boundaries, integration tests run against a real database, and nothing ships unread. The architecture, the decisions and the accountability are mine.
What you're buying
Slicekit is a one-time purchase, not a subscription. You pay once, get the full source under a commercial license, and own it. There is no hosted service to lock you in and no per-seat tax on the product you build on top. Clone the private repo, delete what you do not need, and keep the parts that save you weeks. Lifetime updates are included.
Own the foundation, ship the product
Slicekit hands you the 80% of a .NET SaaS that is the same every time (event-driven architecture, enterprise auth, a finished admin panel, observability and CI) wired together and tested. Buy it once and spend your first month on the 20% that is actually your product.