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Today, Scroll, Axiom, developer Max Gillet and the Ethereum Foundation’s Privacy & Scaling Explorations (PSE) team are announcing OpenVM, an open-source zkVM framework for instant proving.

OpenVM will be adopted by the Scroll L2 as its zkVM, and plans to validate mainnet blocks in coming months. This transitions Scroll from a currently Type-3 to a Type-1 zkEVM — the most fully Ethereum-equivalent zkEVM type.

Scroll’s upgrade to a Stage-1 rollup with a fully functioning proof system will follow soon thereafter.

According to a press release, Scroll’s decision to design a new zkVM from the ground up was driven by a belief that many existing zkVM solutions were “monolithic” and “locking developers into vertically integrated stacks.”

OpenVM’s open-source and modular architecture would enable Scroll to introduce features without making changes to the underlying circuit, and developers to benefit from zkVM improvements without having to modify application code.

The state of ZK

OpenVM joins a market already crowded with zkVMs. Unlike traditional virtual machines, zkVMs are designed to compile and execute smart contracts into zero-knowledge proofs in a secure and private way that does not reveal underlying data.

Today, the zkVM market carries at least a dozen different zkVMs, such as RISC Zero “RISC0” and Succinct’s “SP1.”

Source: Electric Capital

As seen in the below chart, proofs submitted to Ethereum mainnet saw a peak in December 2023, largely coming from zk rollups like Linea, ZKsync and Scroll, rather than applications. Proof volumes saw a drop in 2024, largely due to two factors.

One, proof generation has been increasingly batched using recursive proof aggregation — a technique that verifies multiple proofs within one proof — to reduce costs.

Souce: zkstats.io

Second, proof verification is getting more efficient, so costs are steeply declining from just a year ago.

Prover networks like Risc Zero’s “Boundless” and Fermah have also helped apps and rollups to bring zk-proving costs down. These networks allow teams to outsource proof generation to specialized hardware providers with ASICs and GPUs that compete to generate zk proofs cheaply.

Based on Electric Capital’s recent developer report, there are 2,054 monthly active developers working in zk. The use of zk has seen tremendous growth, with zk contract deployments growing from 40 to 639 today over the last four years.