What is Nussknacker used for?

Nussknacker is a low-code visual tool that lets domain experts build, run and monitor real-time decision algorithms on streaming or request data. It is a good fit for fraud and offer decisioning in real time, and letting analysts own decision logic.

Is Nussknacker open source?

Yes. Nussknacker is open source under the Apache-2.0 licence. Its source code is on GitHub at TouK/nussknacker and is written mainly in Scala.

Yes. Nussknacker is open source, so the software itself is free to use. A managed cloud version is also available.

Can I self-host Nussknacker?

Yes. Nussknacker can be self-hosted on your own server or infrastructure.

What is Nussknacker an alternative to?

Nussknacker is an open-source alternative to Decisions. Other open-source alternatives to Decisions include Corteza, Joget and Windmill.

Is Nussknacker actively maintained?

Yes. The most recent commit to Nussknacker was on 30 September 2026, and the latest release is v1.18.0, published on 22 November 2024. The project has 744 stars on GitHub.

Nussknacker: open-source alternative to Decisions

About Nussknacker

Nussknacker is a low-code visual tool for domain experts to build, run and monitor real-time decision algorithms instead of implementing them in code. Decisions such as which offer a customer gets, who receives a marketing message, whether a device needs servicing or whether something is fraud can be authored and deployed without involving IT.

Authors design scenarios in a visual tool using prebuilt components for routing, filtering, data transformation, time-window aggregations in the Flink engine, enrichments from external databases or OpenAPI endpoints and applying ML models. With one click a scenario is deployed, and it can be changed and redeployed later. Two processing modes are supported: streaming, with Kafka as the main interface for input streams and output decisions, and request-response, which exposes HTTP endpoints with OpenAPI definitions. Batch support is in development.

Nussknacker is written in Scala, licensed under Apache-2.0, and can be installed on your own infrastructure, with a managed Nu Cloud offering also referenced in the README. A demo, documentation and quickstart are linked.

Key features

Visual scenario designer for decisions
Prebuilt components for filters and aggregations
Streaming mode with Kafka
Request-response mode with OpenAPI
Enrichment from databases and APIs
One-click deployment of scenarios

Good fit for

→Fraud and offer decisioning in real time
→Letting analysts own decision logic

Built with: Scala
Tags: low-code; stream-processing; decision-engine; kafka; flink; real-time; rules-engine; scala

Nussknacker: questions and answers

What is Nussknacker used for?: Nussknacker is a low-code visual tool that lets domain experts build, run and monitor real-time decision algorithms on streaming or request data. It is a good fit for fraud and offer decisioning in real time, and letting analysts own decision logic.
Is Nussknacker open source?: Yes. Nussknacker is open source under the Apache-2.0 licence. Its source code is on GitHub at TouK/nussknacker and is written mainly in Scala.
Is Nussknacker free?: Yes. Nussknacker is open source, so the software itself is free to use. A managed cloud version is also available.
Can I self-host Nussknacker?: Yes. Nussknacker can be self-hosted on your own server or infrastructure.
What is Nussknacker an alternative to?: Nussknacker is an open-source alternative to Decisions. Other open-source alternatives to Decisions include Corteza, Joget and Windmill.
Is Nussknacker actively maintained?: Yes. The most recent commit to Nussknacker was on 30 September 2026, and the latest release is v1.18.0, published on 22 November 2024. The project has 744 stars on GitHub.