Collateral-backed gateways to speed Ethereum transactions

Puffer announced on Sept. 22 that Google Cloud will operate a gateway to receive Ethereum transactions and guarantee their execution results before the blockchain reaches finality. The company named its UniFi network as the first to use the gateway. Puffer said the gateway service, called Preconf, is still in testing.

The gateway model is designed to let applications treat a transaction as effectively complete sooner than Ethereum’s on-chain finality. The operator accepts a transaction, promises the execution result — for example the amount received in a swap or transfer — and backs that promise with collateral. Puffer calls those early guarantees preconfirmations.

On Ethereum, blocks are proposed roughly every 12 seconds and finality can take minutes. Many applications already use rollups, which process transactions off the base layer and provide operator-level confirmations before base-layer settlement finishes. Puffer’s preconfirmations focus on promising the execution outcome, not merely inclusion in a block.

Google Cloud’s gateway would accept transactions and promise the final outcome. Puffer said an alternate gateway would take over if Google’s service went offline, creating a handover mechanism for continuity. In the first phase, the gateways — not Ethereum’s base-layer validators — would provide early assurances.

Puffer proposes a slashing mechanism to hold gateway operators to their promises. CEO Amir Forouzani offered a hypothetical and a penalty: “A failed preconfirmation would cost the gateway 1 ETH.” He also described a sample exchange of 1 ETH for a set amount of stablecoin and said Puffer’s transaction times were configured at 50 milliseconds, while noting Ethereum’s own finality remains unchanged.

Several operational details remain unspecified. Puffer has not published how penalized ETH would be distributed, how compensation to affected users would be calculated, or the process for filing claims. Questions include whether an app that releases funds based on a preconfirmation would be reimbursed automatically, who would pay sellers if an original payment failed, and how long any recovery would take.

Collateral sizing and valuation also present issues. An operator could back many preconfirmations with a single collateral pool, and multiple failures could deplete that pool. A fixed penalty denominated in ETH can change in dollar value as market prices move, so a 1 ETH penalty will not always cover the same level of dollar-denominated losses. Puffer’s July 2025 technical outline places slashing in a later phase of the roadmap and the company has not provided a timeline for when stated penalties would become enforceable. Forouzani stated there have been no failures under the current design but did not provide transaction counts or an observation period.

App developers and service operators will need to decide how much risk to accept when they receive a preconfirmation. A marketplace selling low-value digital goods might accept a gateway guarantee and release goods immediately, while a platform handling larger transfers may wait for stronger settlement. The application presenting the confirmation must take responsibility for explaining who bears losses if a preconfirmation fails, since asking users to inspect a gateway’s collateral would be impractical.

Puffer’s gateway experiment remains in testing and requires real customer traffic to demonstrate handovers, penalties and compensation mechanics. The company has provided technical outlines and examples but has not yet shown how the system performs under live conditions or how enforcement of penalties would operate in practice.