Our technology is available under a few different licenses, including open source and proprietary code
  • Cairo Programs: StarkWare’s programs written in Cairo, including business logic included in StarkEx deployments, are licensed under the StarkWare Source Available License.

  • Smart Contracts:StarkWare’s smart contracts on Ethereum are all open source under Apache 2.0. This includes the StarkEx and Cairo Verifiers.

  • StarkEx Cloud Service:The StarkEx prover service running in the cloud is proprietary, and currently operated by StarkWare.
ethSTARK StarkEx
A library implementing ZK-STARK prover and verifier
Scalability engine for commercial deployment
Off-Chain Components
Prover - Open Source

Verifier - Open Source
Prover Service - Closed Source

Cairo Programs - Source Available
On-Chain Components
Cairo Verifier - Open Source


What limitations does StarkWare's Source Available License impose on my use of Cairo programs?

You may distribute and run Cairo programs during the lifetime of the license, but you may not make commercial use of it, nor sell it. For more details, check the terms of the license here. The Source Available License applies for a limited time, while Starkware is considering what terms will apply afterwards.

Why did StarkWare adopt the Source Available License for its Cairo programs?

We wish to allow scrutiny of the programs and allow the public to read and audit the code in a transparent manner, during an initial testing period. StarkWare is still considering which licenses to use in the long term when releasing various components of the Cairo toolchain and applications built on it.  

If you have any questions about our products and how to use them, talk to us: