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Scalus

Scalus is an open-source Scala 3 framework for developing Cardano smart contracts and decentralized applications. It combines a Scala-to-UPLC compiler and optimizer with transaction-building, ledger emulator, testing, debugging and contract-artifact tools, with targets for JVM, JavaScript/TypeScript and Native.

Explore the practical guide ↓

Independent OpenViST project profile, based on linked sources.

Scalus — OpenViST project profile in Developer Tools.
OpenViST project illustration. See the linked sources for product details.
Understand the project

Practical overview

When it fits

Use Scalus when a Cardano project needs a Scala-based workflow spanning validator implementation and compilation, local testing, transaction construction or dApp tooling.

Who it is for

  • Scala developers building Cardano validators or dApps.
  • Cardano developers adopting Scala for contract implementation.
  • Teams testing protocols whose transaction flows and off-chain application logic accompany on-chain contracts.

Documented uses

  • Write Plutus validators with typed datums and redeemers in Scala 3.
  • Compile and optimize Scala contract code into UPLC.
  • Build and evaluate Cardano transactions using ledger and emulator APIs.
  • Test validator logic and multi-transaction scenarios locally.
  • Generate CIP-57 blueprints and use sbt tasks for reference-script deployment.
Before you choose

Requirements & limits

The repository is public and specifies the Apache-2.0 license.

  • The framework is built around Scala 3 and sbt; the README gives Scala 3.3.8 in its installation example.
  • The JVM, JavaScript/TypeScript and Native targets have differing tool coverage; the README specifically describes the fuller Scala developer experience on JVM.
  • An in-memory ledger emulator supports local testing without a running node.
  • The README identifies Java 11 or later and sbt for the default contributor workflow.
  • The repository documents starter templates, example contracts and CIP-57 blueprint generation.

Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.

Source-based practical guide

Create and test a starter validator project

Generate the minimal Scalus validator starter and run its included tests.

Before you start

  • sbt
  • A Scala development environment for the generated project

Steps

  1. Run sbt new scalus3/hello.g8.

  2. Change into the generated hello-cardano directory.

  3. Run sbt test.

Expected outcome

The starter generates a Plutus V3 spending validator, unit tests, integration tests and a compiled contract wrapper; the documented command runs the project tests.

Guide limitations

  • This starter workflow does not document transaction submission or deployment.
  • The project README does not specify the environment setup needed beyond using sbt.
Documentation 1 ↗
Evidence and transparency

Sources & review

Official repository ↗
Source record details
Source availability
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Sources checked
9 October 2026
Original website title
scalus3/scalus · Official homepage title · retained in its source language
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