S-two is live on Starknet

S Two, StarkWare’s next generation open source prover, has officially gone live on Starknet mainnet. S Two (pronounced Stew) is StarkWare’s fully open source prover that replaces Stone, the engine that secured StarkEx & Starknet for the past six years.

• Why It Matters for Starknet
• Client Side & General Purpose Proving
• What’s Next for Starknet

Why It Matters for Starknet

S Two is built on Circle STARKs & the M31 prime field, delivering a major leap in proving efficiency. Benchmarks show that S Two can generate proofs up to 10x faster than its predecessor, cutting computations that once took minutes down to seconds.

With every Starknet block now proven by S Two, the network experiences a significant boost in performance & scalability. The reduction in proof generation costs drastically lowers overall computation expenses, making it feasible to build & run more complex on chain logic at scale.

This enhanced efficiency allows high frequency & computation heavy applications, such as privacy preserving DeFi protocols, verifiable identity systems, & real time data attestations, to operate more economically. Moreover, S Two establishes a stronger foundation for decentralization by creating the technical framework for distributed proving, eliminating single points of failure & strengthening Starknet’s trustless security model.

Client Side & General Purpose Proving

S Two’s optimized backend allows proofs to be generated locally even on low powered devices such as mobile phones. This unlocks a broad new class of applications:

• Private ERC 20 transfers with hidden addresses & amounts
• Privacy preserving DeFi protocols such as dark pools & private trading
• Proof of identity credentials (“I’m human”, “Over 21”, “Hold credential X”)
• Verifiable AI & ML inference, proving model execution on given inputs
  By reducing proving costs & hardware demands, S Two enables user driven proving beyond rollup specific contexts.

It’s S-two fast.

Now live on Starknet Mainnet, and available to every project choosing to build with the SN Stack.

Build for privacy. Build for performance. Build for decentralization. pic.twitter.com/OJmhw9Stvg

— StarkWare (BTCFi arc) (@StarkWareLtd) November 4, 2025

The reduced cost of proof generation paves the way for multi sequencer participation in Starknet. Future upgrades will allow any participant to sequence transactions & generate proofs, ensuring that the network’s state commitments to Ethereum remain uninterrupted even under load or validator churn.

What’s Next for Starknet

Now live on mainnet, S Two transitions from research to full production. The next phase will focus on:

• Further cost optimizations: lowering the cost per proof as adoption scales
• New developer tooling: APIs, templates & libraries for identity, privacy & zkML integrations
• Ecosystem alignment: making S Two the shared proving standard for Starknet & other SN Stack based chains
• Decentralised participation: opening the prover layer to multiple independent sequencers

By combining high performance STARK proofs, client side proving, & a path to decentralised verification, Starknet now stands at the frontier of verifiable computation. From privacy first DeFi to verifiable AI, the S Two era has officially begun, and it’s redefining what’s possible in the zero knowledge world.

If you find any issues in this blog or notice any missing information, please feel free to reach out at yash@etherworld.co for clarifications or updates.

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