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Swaptopia adds no fee of its own. Every fee line in the quote is charged by the Ark server or paid to miners.

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Read the quote

When you enter an amount under You send, the quote fills in You receive with every fee line. To receive a set figure instead, enter it under You receive. Swaptopia then works out the smallest You send amount that pays it out, with the fees on top. Each direction has its own fee lines. Select the Swap direction button to read the other set.

Each direction shows its own fee lines for the same amount

  • Boarding transaction (miner fee): An estimate of the miner fee of the transaction that boards your bitcoin onto Ark. The feerate can change before Swaptopia boards your bitcoin.
  • Service fee 0.5%: The Ark server’s fee for paying your Lightning invoice, as listed on Second’s pricing page.
The Fee paid line on the receipt replaces the estimate with the fees Swaptopia recorded during the swap. For a bitcoin-to-Lightning swap, that is the Lightning service fee, plus the boarding miner fee when Swaptopia could measure it. For a Lightning-to-bitcoin swap, it is the service fee and miner fee of the on-chain payout.

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Service fee

The quote shows a 0.5% service fee, the rate Second’s Ark server charges on bitcoin with 14 days or more of its lifetime left. Bitcoin with less lifetime left pays a lower rate, which the Fee paid line on the receipt reflects. The same goes for leftover sats you send on their own, whose fee can come out lower than the percentage in the label. The full schedule is on Second’s pricing page. Ark fees explains why the rate depends on lifetime.
On small Lightning payouts, the Ark server charges a 20-sat minimum fee instead of the percentage. The line then reads Service fee (minimum 20 sats).

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Miner fees

Each direction’s quote carries one miner fee:
  • Boarding transaction (miner fee): Swaptopia prices the board at the current 3-block feerate from Second’s Esplora server (mempool.second.tech on mainnet), or higher if its wallet estimates more. This fee comes out of the bitcoin that arrives. Your on-chain wallet app pays its own miner fee on top to reach the funding address.
  • On-chain miner fee: The Ark server charges the miner fee of the payout transaction to your address as part of the swap.
If the quote says the boarding transaction’s miner fee “cannot be priced right now”, Swap stays disabled. Wait a moment, then edit the amount or select a preset to quote again.

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Amount limits

Swaptopia checks your amount against these limits and tells you which one you hit. The Ark server accepts a board of at least 50,000 sats on mainnet (10,000 on signet), counted after the boarding transaction’s miner fee comes out. So a bitcoin-to-Lightning swap adds room for that fee: at least 1,000 sats, and more once the feerate passes about 2 sat/vB. If you enter less, Swaptopia raises the amount to the smallest one that boards. A note on the swap card says so.

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Preview mainnet fees from signet

On signet, Swaptopia can quote a swap at mainnet rates while your test bitcoin stays on signet, so you see the real cost before you switch.
1

Select Preview mainnet fees

The link sits under the Swap button. A banner confirms the preview. The status bar reads mainnet preview.
2

Enter an amount

The quote shows mainnet fee lines, as described in Read the quote. Swap stays disabled during the preview.
3

Select Back to signet quotes

Swaptopia closes the banner and quotes from the signet server again.

The mainnet preview quotes real fees. Swap stays disabled until you go back to signet quotes