What is Rootstock (RSK)?

Rootstock (RSK) is a Bitcoin sidechain that lets developers run smart contracts and DeFi apps while using bitcoin as the native currency. It is compatible with the Ethereum Virtual Machine, so tools and contracts written for Ethereum can often be reused. Rootstock's coin, RBTC, is pegged one to one with BTC and pays for gas on the network.

What is Rootstock smart bitcoin (RBTC)?

RBTC is what Rootstock calls smart bitcoin. Rootstock describes it as having a direct one-to-one peg with bitcoin, so one RBTC is meant to represent one BTC locked on the Bitcoin blockchain. RBTC pays for transactions and smart contract execution on Rootstock, much as ETH pays for gas fees on Ethereum.

Because the BTC behind RBTC is held in a Bitcoin multisig rather than by the user, holding RBTC is not the same as holding BTC in your own wallet. It is closer to other forms of wrapped bitcoin, with its own custody design.

How do you move BTC to Rootstock?

Moving between the two chains uses the PowPeg. In a peg-in, you lock BTC on Bitcoin and the Rootstock Bridge contract releases RBTC to you. According to Rootstock's developer docs, this requires 100 Bitcoin confirmations, and the company's blog puts the full process at about 16 hours. In a peg-out, you send RBTC back to the Bridge, and BTC is released after confirmations and signatures. As of November 2026, the docs list minimums of 0.005 BTC for a peg-in and 0.004 RBTC for a peg-out.

The signing keys sit inside tamper-resistant devices called PowHSMs. Each one runs a Rootstock node and only signs when it sees enough accumulated proof of work behind a request. The operators who host these devices, called functionaries, keep them online but do not choose where funds go. Rootstock's docs say the peg began as a federation when the network launched in 2018 and was redesigned as the PowPeg starting in 2020. Users still rely on this setup working as intended, which is a different trust model from Bitcoin itself.

What is RSK sidechain merged mining?

Merged mining lets Bitcoin miners secure Rootstock at the same time as Bitcoin, because both use the same double SHA-256 proof of work. Mining pools add a reference to the current Rootstock block inside their Bitcoin block template. When a miner's work meets Rootstock's difficulty, it counts as a Rootstock block, even if it is not enough for a Bitcoin block. Miners earn a large share of Rootstock transaction fees for no extra hashing.

RootstockLabs reported that merged mining covered about 84% of Bitcoin's hashrate in the first quarter of 2026, with large pools such as Foundry USA and AntPool taking part. That makes rewriting Rootstock's history costly, but it also means a small group of pools has a large say in the network. Hashrate figures change over time.