Eureka Labs Launches ‘BEX’ Execution Engine on Ethereum Mainnet
Tel-Aviv, Israel, October 29th, 2026, Chainwire
Ethereum is still testing a 200 million gas limit for its next upgrade. Eureka’s BEX already runs 500 million gas per request on mainnet, at no gas cost. Version two, coming in 2027, adds live real-world data and code written in any language.
Every program on Ethereum has lived under the same four limits since 2015. Code runs only inside a transaction, only within the block’s gas limit, only in Solidity, and only with data that is already onchain.
Eureka, one of the largest block builders on Ethereum, is removing them all. The first version of BEX is live on Ethereum mainnet today and lifts the first two: it runs developers’ code inside the block builder while the block is being assembled, with up to 500 million gas per request and no fee until something lands. The second version, coming in 2027, lifts the last two: live real-world data streamed into that code in the middle of the block, and programs written in Rust, Go or any language that compiles to WebAssembly.
On a typical day, Eureka’s builders run about 5 million BEX computations. More than 40% of BEX requests used more gas than an entire Ethereum block, and the largest passed 400 million gasses. Added up, Eureka’s builders now run hundreds of times more computation every day than the whole Ethereum network can process onchain.
“Ethereum gave developers smart contracts in 2015. BEX gives them the block itself,” said Nir Magenheim, CEO of Eureka. “For ten years the whole industry has been trying to squeeze more into the block. We went around it. The builder sees the entire block before anyone else, and we are handing that machine to developers. No other builder on Ethereum does this.”
An Overview of BEX
A block builder decides which transactions go into a block and in what order. Normally code runs only once a transaction is already in the block, and every step cost gas and takes space other transactions could use.
With BEX, code is sent to Eureka instead of a finished transaction. Eureka runs it against the block as it builds, so the code sees the latest prices and balances, including the effect of every transaction placed ahead of it. When it finds something worth doing, Eureka turns the result into a small transaction and drops it into the same block. When it finds nothing, nothing goes onchain and nothing is paid. The computation itself never touches the chain, which is why Ethereum’s gas limit stops being the ceiling on what a program can do.
Teams are already landing BEX transactions on mainnet, with some blocks carrying four or five at once. The first users are searchers, the trading teams that find price gaps between markets and close them.
One searcher using BEX put it this way: “BEX lets us run our strategy’s compute against the builder’s evolving block state. As a searcher without extensive private orderflow, this lets us respond to opportunities without needing to receive the underlying transactions ourselves.”
Understanding the Timing
Ethereum’s next upgrade, Glamsterdam, includes ePBS, which makes block builders part of the Ethereum protocol itself. Eureka grew from building 1% of Ethereum blocks to 10% this year, and it is the first builder to turn that position into something developers can program.
“Once builders are inside the protocol, the question becomes what a builder can do for you,” Magenheim said. “Ordering transactions is the basic job. Running your code against the live block, feeding it real-world prices as they move, protecting your funds while the block is still open: that is where the value is going”
Moving Forward
Version two opens the block to the real world. Code running inside the block will be able to call anything on the internet and act on the answer in that same block. A lottery could draw its winner from a true random number source. A wallet could refuse to move funds unless a Google Authenticator code checks out. A prediction market could settle the moment the final whistle blows. An institution could set up a protective transaction that fires the instant an exploit or a depeg shows up in the block, landing in the same block as the attack. And with WebAssembly, developers will write all of that in Rust, Go or any language they already use.
“BEX started with searchers. Next, it opens to applications,” said Marissa Posner, Eureka’s Head of Product. “A block takes 12 seconds to build, and prices move the whole time. An application should be able to push its latest price right up until the block closes, not settle for one from 12 seconds ago.”
Eureka will run hands-on BEX workshops next month and release an open-source SDK. The BEX docs explain how to send a first request.
About Eureka Labs
Eureka Labs develops Ethereum block-building infrastructure and tools that make blocks programmable for developers. The company was founded in December 2024 and is based in Tel Aviv.
Website: https://eurekalabs.xyz
Telegram: https://t.me/EurekaBuilder