Our technology is available under a few different sets of terms, some open source, and some source-available.
  • Smart Contracts: StarkWare’s smart contracts on Ethereum are all open source under Apache 2.0. This includes the StarkEx and Cairo Verifiers.
  • Cairo Programs: StarkWare’s programs written in Cairo, including business logic included in StarkEx deployments, are licensed under the StarkWare Source Available License.
  • Cairo Compiler Toolchain: The toolchain used for developing Cairo programs is licensed under the StarkWare Toolchain license.
  • Prover: Cairo and StarkNet Provers will be released at a later date under the Polaris License.
  • StarkEx Cloud Service: The StarkEx Prover cloud service is closed source, and currently operated by StarkWare
ethSTARK StarkEx StarkNet / Cairo
Description
A library implementing ZK-STARK prover and verifier
Scalability engine for commercial deployment
Scalability for L2 dApp developers
Off-Chain Components
Prover - Open Source

Verifier - Open Source
Prover Service - Closed Source

Cairo Programs - Source Available
Cairo Toolchain: StarkWare Toolchain License

Prover Service - Closed Source

StarkNet Prover (arriving later) - Polaris Source Available
On-Chain Components
None
Cairo Verifier - Open Source
StarkNet Polaris Verifier (arriving later) - Open Source

ethSTARK

Description

A library implementing ZK-STARK prover and verifier

Off-Chain Components

ProverOpen Source

VerifierOpen Source

On-Chain Components

None

StarkEx

Description

Scalability engine for commercial deployment

Off-Chain Components

Prover Service – Closed Source

Cairo ProgramsSource Available

On-Chain Components

Cairo Verifier – Open Source

StarkNet / Cairo

Description

Scalability for L2 dApp developers

Off-Chain Components

Cairo Toolchain: StarkWare Toolchain License

Prover Service – Closed Source

StarkNet Prover (arriving later) – Polaris Source Available

On-Chain Components

StarkNet Polaris Verifier (arriving later) – Open Source

FAQs

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.

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

Informally, the Polaris license says that anyone may use and modify the Prover code, including for commercial use, as long as proofs generated by it are submitted to one of the white-listed Polaris Verifiers. A white-listed Verifier is a smart contract address appearing on an append-only list, which means that StarkWare may only add Verifiers to that list, but never remove them.

The name Polaris (North Star) captures the essence of the license. The Polaris is a faithful address to which compasses and maps can be pointed, assisting free-roaming travellers on their myriad forays. Like the star, a Polaris Verifier is everlasting and unchanging. More coming soon.

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