Peter Todd, a longtime Bitcoin Core contributor and co-author of replace-by-fee (BIP 125), has joined the MARA Foundation as lead maintainer of Slipstream, the miner's private Bitcoin transaction pipeline, the foundation announced Thursday.

The appointment places one of Bitcoin's most active protocol researchers at the helm of a service aimed at institutional and high-value users who want their transactions kept out of the public mempool until confirmation. MARA operates Slipstream alongside MARA Pool, its mining pool, turning the infrastructure into a vertically integrated transaction-privacy product.

What does Slipstream actually do?

Slipstream routes user transactions directly to MARA Pool, bypassing Bitcoin's public peer-to-peer network. Standard Bitcoin transactions broadcast through a node enter a globally visible waiting area, the mempool, before inclusion in a block. Slipstream sends the transaction straight to the miner, so its contents — including the public keys being spent — stay hidden until a block confirms them.

That mechanic eliminates exposure to front-running and pre-confirmation surveillance, a category of risk that has grown as more sophisticated actors monitor the public mempool for high-value or vulnerable transactions.

What pushed MARA to invest in private ordering?

MARA pointed to the July Coldcard hardware wallet exploit, in which attackers stole more than $115 million from user wallets. By the company's framing, Slipstream is a structural mitigation: keeping transactions out of public view removes the surveillance channel that attackers monitor for vulnerable signing flows or unusually large spendable balances.

The service had already drawn attention in 2024 for publishing unusually large Ordinals inscriptions, surfacing during the early wave of activity around on-chain data embedding. More recently it has hosted research projects including Quantum Safe Bitcoin and Binohash, an effort to emulate covenant spending conditions without a soft fork.

Who is Peter Todd?

Todd has worked on Bitcoin protocol software since the early 2010s. He co-authored BIP 125, which lets senders replace an unconfirmed transaction with a higher-fee version, and created OpenTimestamps, a cryptographic timestamping tool used across the Bitcoin ecosystem. In 2024 he launched Libre Relay, a Bitcoin Core fork that loosens relay rules for non-standard transactions, including the Ordinals-related formats that default policy rejects.

He has argued consistently that relay policy should track what miners are willing to include in blocks, rather than impose additional restrictions on transaction formats users want to send.

What does Todd plan at Slipstream?

Todd cast the role as a research position as much as an operational one.

"I most look forward to seeing what's possible on Bitcoin — using Slipstream as a proving ground for experimental development and protocol innovation," Todd said.

The MARA Foundation did not disclose the term, scope or compensation for the appointment. Slipstream remains opt-in and competes with other private-pool offerings — including independent transaction-broadcast services and dark-pool-style mining operations — as institutional demand for non-custodial transaction privacy reshapes Bitcoin's market structure.