IDEX, the top decentralized exchange (DEX) for ERC-20 tokens in 2019, according to etherscan, is in the process of launching a new DEX on top of Rollup technology, a Layer 2 scalability protocol highlighted in ethereum’s latest “Istanbul” hard fork. As part of the relaunch, a demo was released on Thursday.

A non-contentious hard fork, Istanbul consists of six ethereum improvement proposals (EIPs) including EIP 2028, which reduces the gas fee for requesting calldata from 68 gas per byte to 16 gas per byte. Calldata is information broadcast on the ethereum state necessary for creating specific smart contracts.

By reducing gas fees, Rollup-based smart contracts, which bundle on-chain transactions off-chain, have become an expedient scalability tool – for IDEX and others.

In an email sent to CoinDesk after the initial publication of this article, IDEX said its rollup design, the Optimized Optimistic Rollup (O2R), was developed independently of the Istanbul hard fork.

Istanbul includes code improvements capable of supporting Layer 2 systems such as Rollups, a tech first developed in 2018 by ethereum developer barryWhiteHat and ethereum co-founder Vitalik Buterin. The improvements were created with the intent of fostering privacy-based, Layer 2 solutions on ethereum.

Aurora Labs CTO Jason Ahmad said IDEX was looking for different Layer 2 solutions for scaling when his team found Optimistic Rollups, created by ConsenSys scalability researcher John Adler and also ethereum scalability project Plasma Group, at this year’s Devcon, an Ethereum hackathon in Osaka, Japan, two months before the planned ethereum hard fork.

Ahmad said IDEX’s O2R improves on Adler’s design, giving it “unbounded” scalability – a handy feature given the amount of contracts an exchange settles daily. Unboundedness is a feature Adler has publicly disputed.

“As the creator of optimistic rollup, that kind of behavior saddens me, because the design paradigm can easily stand on its own merits without being fluffed up,” Adler said in a message to CoinDesk. (Adler, it should be noted, is a co-founder of Fuel, one of about 10 firms working on Rollups.)

Adler specifically pointed out the claim of “instant, gas-free transactions” as being untrue, saying in an email all contracts must sync back to the mainchain at some point which has inherent gas requirements. The two entities have since gone public with their disagreements, feuding Friday on Twitter.

For Aurora Labs, the company behind IDEX, Rollups mean lowering operating costs as well as boosting transaction speeds, Ahmad said. The CTO expects IDEX’s O2R Rollups to reduce gas fees by as much as 90 percent on the new platform.

“The design for off-chain exchange functionality with on-chain custody and settlement is much more efficient, much more cost-effective and frankly is a better judicious use of the scarce blockchain resource,” Ahmad said.

Update (Dec. 5, 18:25 UTC): A prior version of this story said the new IDEX platform was launching Thursday. Only a demo is currently available.

Update (Dec. 6, 21:25 UTC): This piece has been updated with additional information and the headline has been changed.