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A SDK to interact with Clarity Smart Contracts

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Clarinet SDK

The Clarinet SDK can be used to interact with the simnet from Node.js.

Find the API references of the SDK in our documentation.
Learn more about unit testing Clarity smart contracts in this guide.

You can use this SDK to:

  • Call public and read-only functions from smart contracts
  • Get clarity maps or data-var values
  • Get contract interfaces (available functions and data)
  • Write unit tests for Clarity smart contracts


npm install @hirosystems/clarinet-sdk


import { initSimnet } from "@hirosystems/clarinet-sdk";
import { Cl } from "@stacks/transactions";

async function main() {
  const simnet = await initSimnet();

  const accounts = simnet.getAccounts();
  const address1 = accounts.get("wallet_1");
  if (!address1) throw new Error("invalid wallet name.");

  const call = simnet.callPublicFn("counter", "add", [Cl.uint(1)], address1);
  console.log(call.result); //

  const counter = simnet.getDataVar("counter", "counter");
  console.log(counter); //


By default, the SDK will look for a Clarinet.toml file in the current working directory. It's also possible to provide the path to the manifest like so:

 const simnet = await initSimnet("./path/to/Clarinet.toml");


The SDK can be used to write unit tests for Clarinet projects.

You'll need to have Node.js (>= 18) and NPM setup. If you are not sure how to set it up, Volta is a nice tool to get started.

In the terminal, run node --version to make sure it's available and up to date.

Note: A bit of boilerplate is needed to setup the testing environment. Soon it will be handled by the clarinet-cli.

Open your terminal and go to a new or existing Clarinet project:

cd my-project
ls # you should see a Clarinet.toml file in the list

Run the following command to setup the testing framework:

npx @hirosystems/clarinet-sdk

Visit the clarity starter project to see the testing framework in action.

Type checking

We recommend to use TypeScript to write the unit tests, but it's also possible to do it with JavaScript. To do so, rename your test files to .test.js instead of .test.ts. You can also delete the tsconfig.json and uninstall typescript with npm uninstall typescript.

Note: If you want to write your test in JavaScript but still have a certain level of type safety and autocompletion, VSCode can help you with that. You can create a basic jsconfig.json file:

  "compilerOptions": {
    "checkJs": true,
    "strict": true
  "include": ["node_modules/@hirosystems/clarinet-sdk/vitest-helpers/src", "unit-tests"]


The clarinet-sdk requires a few steps to be built and tested locally. We'll look into simplifying this workflow in a future version.

Clone the clarinet repo and cd into it:

git clone
cd clarinet

Open the SDK workspace in VSCode, it's especially useful to get rust-analyzer to consider the right files with the right cargo features.

code components/clarinet-sdk/clarinet-sdk.code-workspace

The SDK mainly relies on two components:

  • the Rust component: components/clarinet-sdk-wasm
  • the TS component: components/clarinet-sdk

To work with these two packages locally, the first one needs to be built with wasm-pack and linked with: npm link.

Install wasm-pack and run:

cd components/clarinet-sdk-wasm
wasm-pack build --release --target=nodejs --scope hirosystems
cd pkg
npm link

Go to the clarinet-sdk directory and link the package that was just built. It will tell npm to use it instead of the published version. You don't need to repeat the steps everytime the clarinet-sdk-wasm changes, it only needs to be rebuilt with wasm-pack and npm will use it.

Built the TS project:

cd ../../clarinet-sdk
npm link @hirosystems/clarinet-sdk-wasm

You can now run npm test, it wil be using the local version of clarinet-sdk-wasm



Last updated on 28 Jun 2024

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