## What’s AltLayer

AltLayer is an open and decentralized protocol for rollups. AltLayer brings together novel ideas, such as __Restaked rollup__, which takes existing rollups (spun from any rollup stack such as OP Stack, Arbitrum Orbit, ZKStack, Polygon CDK, etc.) and provides them with enhanced security, decentralization, interoperability, and crypto-economic fast finality.

With this latest integration, Nebra’s UPA will aggregate the proofs into smaller units and settle them on Ethereum. This will enable our builders and users to benefit from reduced on-chain verification costs and improved interoperability.

## NEBRA’s Role

At NEBRA, we talked to many developers who want to launch rollup-based AppChains. The primary concern that prevents people from launching a ZK-based AppChain today is cost. And the cost can be broken down into the prover cost and verification cost. With the rapid progress of the zero-knowledge proof system, the prover cost has been reduced dramatically over the years, however, the verification cost remains a high barrier to entry to many builders. Here is a break-down of the Rollup verification cost (in USD) for rollup runners:

As shown in the table, even if a zkRollup settles the proof at a low frequency (once every hour), the rollup runner still needs to pay tens of thousands of dollars for the verification cost. We predict that the high performance rollups especially those are handling big trading volumes or developing latency sensitive gaming will settle the proof more frequently, even at the rate of every single block (a.k.a. Proof Singularity). This high proof verification cost is one of the biggest problems preventing people from building the next 10,000 zkRollups.

__NEBRA UPA (Universal Proof Aggregation)____ __solves the problem by using recursive snarks. NEBRA brings the shared economy to zero-knowledge proof verification. Thanks to its universality, proofs from different sources, such as zkML, zkRollup, zkDID, zkCoprocessors can be aggregated into a single proof and the verification cost gets amortized.

The figure below shows ZKP verification cost using NEBRA UPA with various batch size (https://docs.nebra.one/developer-guide/gas-costs)

The NEBRA team is more than excited to work alongside Altlayer to bring the next 1,000 zkRollups.

## Interested in building with NEBRA?

If you are interested in trying out NEBRA’s UPA __click here__.