Tools for the Concerto Modeling Language

Usage no npm install needed!

<script type="module">
  import accordprojectConcertoTools from 'https://cdn.skypack.dev/@accordproject/concerto-tools';



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Concerto is a lightweight 100% JavaScript schema language and runtime. It works in both a Node.js process and in your browser. The browserified version of Concerto is ±280KB. We are working on making it even smaller.

This is why you should care: https://www.accordproject.org/news/strongly-typed-data-for-javascript-and-beyond/

Things you can do using Concerto:

  • Define an object-oriented model using a domain-specific language that is much easier to read and write than JSON/XML Schema, XMI or equivalents. The metamodel gives you "just enough" expressivity to capture real-world business models, while remaining easy to map to most runtime environments.
  • Optionally edit your models using a powerful VS Code add-on with syntax highlighting and validation
  • Create runtime instances of your model
  • Serialize your instances to JSON
  • Deserialize (and optionally validate) instances from JSON
  • Instances are JS objects so they are easy to pass around your application
  • Introspect the model using a powerful set of APIs
  • Convert the model to other formats: JSON Schema, XML Schema, Java, Go, Typescript, Loopback, PlantUML using concerto-tools.
  • Import models from URLs
  • Publish your reusable models to any website, including the Accord Project Open Source model repository, hosted at: https://models.accordproject.org

Structure of the Code Repository

Top level repository (concerto), with sub packages. Each sub-package is published as an independent npm module using lerna:

  • concerto-cli : command-line interface for Concerto
  • concerto-core : core library for model management/parsing/validation/serialization
  • concerto-tools : model converters and tools for Concerto model files


To install the command-line interface:

npm install -g @accordproject/concerto-cli

You may also set a custom folder to keep the log files by setting the following environment variable:


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Accord Project is an open source, non-profit, initiative working to transform contract management and contract automation by digitizing contracts. Accord Project operates under the umbrella of the Linux Foundation. The technical charter for the Accord Project can be found here.

Learn More About Accord Project




The Accord Project technology is being developed as open source. All the software packages are being actively maintained on GitHub and we encourage organizations and individuals to contribute requirements, documentation, issues, new templates, and code.

Find out what’s coming on our blog.

Join the Accord Project Technology Working Group Discord Community to get involved!

For code contributions, read our CONTRIBUTING guide and information for DEVELOPERS.


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