// the find
nexus-xyz/nexus-zkvm
The Nexus zkVM: The zero-knowledge virtual machine
A RISC-V zkVM built on StarkWare's Stwo prover, targeting developers who need to prove arbitrary computation without writing circuits by hand. You write a Rust program targeting RISC-V, compile it, and Nexus generates a STARK proof of its execution. Still firmly in alpha — the README says so explicitly.
The Stwo backend is a real differentiator: Circle STARKs over the Mersenne31 field are significantly faster to prove than older Plonk/Groth16 approaches, and StarkWare's benchmarks back that up. The precompile system is well-designed — you can extend the VM with custom operations (keccak is already in) without forking the core, and the macro-based API keeps boilerplate low. The modular prover/prover2 split shows they're actively iterating on the proving architecture rather than locking in early decisions. The full formal specification PDF is included in the repo, which is rare and matters a lot when you're trying to audit a cryptographic system.
There are two prover directories (prover/ and prover2/) with no clear explanation in the README or docs about which one to use or what the migration status is — that's a real footgun for anyone trying to build on this. Proof sizes and verification costs are not documented anywhere visible; for a zkVM you need those numbers before you can decide if it fits your use case. The 'legacy' examples directory suggests at least one breaking redesign has already happened with no clear migration guide. Alpha status combined with active architectural churn means anything you build on this today will likely need significant rework when they stabilize the API.