Peter Todd takes lead of MARA’s Slipstream as private mempools gain ground

Long-time Bitcoin Core contributor Peter Todd has stepped into the role of head maintainer for Slipstream, a MARA Foundation service that routes transactions directly to MARA Pool, bypassing Bitcoin’s public peer-to-peer network.

Todd brings a fitting background to the position. Having spent a significant amount of time working on transaction relay and fee policies, his expertise aligns well with Slipstream, which is built to handle transactions that struggle to move through standard mempools.

The developer behind RBF now runs a private channel

For quite some time, Todd has researched how unconfirmed Bitcoin transactions move. He co-authored BIP 125 to develop and standardize opt-in replace-by-fee, and subsequently built Libre Relay, a modified iteration of Bitcoin Core featuring relaxed relay rules.

Todd shared his new role with Slipstream independently, immediately connecting it to the broader conversation surrounding private mempools:

“Announcement: I’m now the lead maintainer of Slipstream @MARAFoundation_
I’ll actually be giving a short talk on private mempools at the upcoming TABConf – it’s really interesting how Slipstream was useful during the coldcard hack.” — Peter Todd, in a post on X

His mention of the Coldcard incident highlights that private mempools stretch beyond mere technical debates, proving that keeping a transaction hidden from the public eye can have practical real-world implications.

What the relay policy actually blocks

A distinction exists between Bitcoin’s consensus mechanism and its relay policy. Bitcoin Core documentation defines relay policy as a collection of supplementary, locally configurable rules that nodes apply to unconfirmed transactions before allowing them into their mempools. Once a transaction is successfully included in a block, these specific rules no longer apply.

Slipstream provides a way around standard relay paths. MARA launched the service in February 2024 to handle large or non-standard transactions. By using MARA Pool directly, users can complete transactions that comply with Bitcoin’s core principles and fee requirements without depending on public relay methods.

Coldcard recovery and quantum experiments

Coldcard issued an advisory in July 2026 warning that any firmware version released between 2021 and July 2026 could potentially generate flawed entropy. Affected users were urged to regenerate their secrets and take immediate steps to move their funds on-chain.

One challenge was that recovery transactions exposing a multisig script could linger unconfirmed long enough for attackers to spot them and broadcast a competing transaction with a higher fee. Todd highlighted Slipstream as a tool to mitigate that danger by concealing the transaction from the public mempool until it reached a block:

“because they promise to keep your transaction – and thus pubkeys – secret until they’re already in a block. Dramatically reducing the ability of the attacker to steal the funds.”— Peter Todd, quoted by Bitcoin Magazine

He further noted that this protection works best when addresses have not been previously reused:

“If you’ve already reused addresses, this isn’t relevant, and you should just try to move your funds ASAP. But if you haven’t, MARA may be able to help.” — Peter Todd, quoted by Bitcoin Magazine

The MARA Foundation later reported that Slipstream enabled the safe transfer of more than 9,000 BTC originating from vulnerable multisignature wallets.

The platform has also supported experimental transactions. Cryptopolitan previously noted that StarkWare’s first quantum-safe Bitcoin transaction reached the mainnet via Slipstream after failing to pass through the conventional mempool.

Ultimately, private channels like Slipstream give miners alternative pathways to process transactions that might otherwise be blocked by public relay rules—whether during emergency recoveries like the Coldcard incident or during testing phases like StarkWare’s quantum-safe transactions. However, this method keeps operations outside the public mempool. Todd’s involvement with Slipstream raises important questions about how much miner-controlled channels might transform Bitcoin routing going forward.

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