Mempool Accelerator Launches Off-Chain Service for Bitcoin Transactions

Mempool, a blockchain explorer for Bitcoin (BTC), has introduced an off-chain service named Mempool Accelerator to assist users in expediting unconfirmed transactions.

Service Overview

The Mempool Accelerator allows users to expedite what are termed as “stuck transactions” by paying an additional miner fee alongside a service charge. Users can locate their unconfirmed transactions on mempool.space, select the acceleration option, and pay via Bitcoin (using Lightning) or fiat through Cash App, Apple Pay, or Google Pay. Importantly, there is no signup process required.

Mining Pool Partners

The service initially collaborates with five mining pool partners: Foundry USA Pool, MARA Pool, SBICrypto, SpiderPool, and Ocean Pool, which collectively make up approximately 40% of the global Bitcoin hashrate. When a transaction is accelerated, Mempool sends an acceleration request to its mining pool partners, who can opt to prioritize that transaction by applying a new accelerated fee rate.

Although the transaction is not replaced, it is perceived as having a higher fee, thereby increasing the probability of confirmation in the forthcoming block, though such confirmation is not guaranteed. The service is also available for integration via API for Bitcoin applications.

Transparency and Limitations

Mempool ensures transparency by making acceleration bid boosts publicly visible on its block audit dashboard, where they are highlighted in purple. It is crucial to note that submitted acceleration requests cannot be altered, and some requests may be canceled without refunds to prevent misuse such as “transaction pinning.”

Comparison to On-Chain Methods

The Mempool Accelerator provides an alternative to typical on-chain methods for boosting the chances of miner inclusion, such as replace-by-fee (RBF) and child-pays-for-parent (CPFP).
– RBF: The sender creates a new transaction with a higher fee that may replace the original. This requires a new transaction to be signed and support from the sender’s wallet.
– CPFP: The recipient increases the fee of an unconfirmed transaction by spending the unconfirmed output, again requiring a signed transaction and wallet support.

However, Mempool Accelerator opts for an out-of-band payment instead of necessitating a new on-chain transaction, which does simplify the process but relies on a centralized third party instead of a decentralized network.

Cost Considerations

The service charge for Mempool Accelerator is considerably higher than typical transaction fees—around 100 times the average fee of $0.39, according to findings from The Block. Users can expect their transaction to be prioritized by up to 43.4% of miners, potentially reducing the waiting time for confirmation to approximately 9 minutes.

Mempool advises users to use RBF or CPFP whenever feasible, although the accelerator service remains advantageous in situations involving limited wallet functionality, multisig transactions, Lightning channel management, and maintaining the same transaction ID, among other cases.