The Nil Foundation, which is written as =nil; Foundation, has raised $22 million in a round led by Polychain Capital. The round, which closed toward the end of last year, brings the foundation’s valuation to $220 million and sees participation from other investors including Blockchain Capital, Starkware and Mina Protocol, according to the release.

Founded in 2018, Nil is the developer of the Proof Market protocol, which enables Layer 1 and Layer 2 blockchains and protocols to generate zero-knowledge (ZK) proofs on demand. A ZK proof is a cryptographic technique that confirms whether a statement is true or false without revealing that statement’s contents.

The raise comes as a new crop of ZK start ups jostle for market prominence. Ulvetanna, a startup that builds hardware to increase the efficiency of ZK proofs, also announced today it has raised $15 million in seed funding from Bain Capital Crypto and web3 venture firm Paradigm, among others.

The Nil Foundation’s protocol aims to solve this challenge with a protocol that enables to developers to list orders specific to their needs and for proof generators to meet those needs.