Guide · Bitcoin to Fractal

How to bridge BTC to Fractal Bitcoin

Bitcoin and Fractal Bitcoin are two separate chains. This guide explains what happens when you move BTC across, what you need beforehand, and how to do it step by step with the deposit flow in the FENNEC Terminal.

Two chains, one wallet

Fractal Bitcoin is its own blockchain, built from the Bitcoin Core code base, with its own native coin, FB, and blocks roughly every 30 seconds. It uses the same key and address formats as Bitcoin, so one UniSat Wallet account can hold assets on both networks — you switch between Bitcoin mainnet and Fractal mainnet inside the wallet.

Coins do not travel between the two chains on their own. BTC sitting on Bitcoin mainnet stays there until a bridge takes it in and credits an equivalent balance on Fractal. FB, on the other hand, is native to Fractal and never needs bridging.

What the FENNEC bridge actually does

On FENNEC, bridging BTC is simply a Deposit in the Terminal with BTC selected. The Terminal uses the deposit API of InSwap, the BRC-20 swap module operated by UniSat on Fractal:

1. The Terminal asks UniSat to switch to Bitcoin mainnet.
2. It requests a deposit transaction (a PSBT) for the amount you entered.
3. You review and sign that transaction in UniSat; it is then broadcast on Bitcoin.
4. After the Bitcoin transaction confirms, InSwap credits bridged BTC to your InSwap balance on Fractal. InSwap lists it under the tick sBTC___000; FENNEC displays it as BTC.

The bridged BTC lands in your InSwap balance, not as coins in your wallet. From there you can trade it on the BTC/FB market or any other pair, or withdraw it back to Bitcoin later. The bridge itself is InSwap's infrastructure: FENNEC builds the request and shows its progress, but it does not hold or back the bridged BTC.

What you need before you start

• UniSat Wallet (browser extension), connected to fennecbtc.xyz.
• BTC on your Bitcoin mainnet address — enough for the amount plus the Bitcoin network fee.
• At least 0.00001 BTC, the smallest deposit the Terminal accepts.
• A fee rate: Fast, Normal or a custom sat/vB value (up to 2,000 sat/vB). A higher rate usually confirms sooner.

Step by step: bridge BTC with the Terminal

1. Open the FENNEC Terminal and click Connect.
2. Go to the Deposit tab and select BTC.
3. Enter the amount you want to bridge (0.00001 BTC or more).
4. Pick the Bitcoin network fee rate.
5. Click Deposit. UniSat switches to Bitcoin mainnet and shows the transaction — check the amount and fee, then sign.
6. The Terminal confirms the deposit with InSwap and tracks it under Recent Deposits and in the pending-operations bell.
7. Wait for Bitcoin to confirm the transaction. Bitcoin blocks arrive about every ten minutes on average, so timing depends on the fee rate and network load.
8. Once credited, BTC appears in your InSwap balance and you can swap it for FB or BRC-20 tokens.

Bringing BTC back to Bitcoin mainnet

Use the Withdraw tab with BTC selected. The minimum withdrawal is 0.00004 BTC. The withdrawal moves the amount out of your InSwap balance and pays it to your Bitcoin address; network fees apply, and you set the fee rate the same way as for deposits.

Things to know

• Bridged BTC is an InSwap ledger balance. A block explorer cannot show it; the Terminal and the wallet menu read it from the InSwap API.
• Swaps are charged in FB. The InSwap fee on a swap is quoted in FB before you sign, so plan to hold some FB on Fractal.
• A pending deposit is normal. Until Bitcoin confirms the transaction, the deposit stays pending; do not send it twice.
• Only sign what you understand. FENNEC never asks for your seed phrase, and the site lives at fennecbtc.xyz.

Related: Swap FB and BRC-20 · Launch a BRC-20 token · FAQ