What is Liquid Network and how does EclairBTC use it?

When a customer uses your EclairBTC POS and pays you using Lightning Network, EclairBTC creates a Boltz Lightning -> Liquid swap and deposits the Bitcoin in your Liquid wallet minus a small fee.  

Liquid is a Bitcoin sidechain built by Blockstream and launched in 2018. Unlike payment protocols built on top of Bitcoin, Liquid runs as a parallel network with its own block production and its own native asset, Liquid Bitcoin (LBTC), which is backed 1:1 by Bitcoin held on the main chain. One LBTC can always be redeemed for one BTC through the peg mechanism, and the total supply of LBTC is fully collateralized by real Bitcoin at all times.

EclairBTC uses Liquid network because it gives merchants a fast and simple way to privately receive Bitcoin.

Speed: Liquid produces blocks every minute, compared to Bitcoin's roughly ten minutes. Transactions reach finality in about two minutes, which is slower than Lightning's near-instant settlement but fast enough for any everyday payment scenario, from paying rent to splitting a dinner bill. Native Liquid transactions carry minimal fees and require no channel management of any kind.

Privacy: Liquid uses Confidential Transactions by default, meaning the amount and asset type are cryptographically hidden from outside observers. Anyone can verify that a transaction is valid, but without the explicit consent of the parties involved, no one can see how much was sent. On Bitcoin's base layer, every amount is fully visible on-chain. On Lightning, payment routing reveals partial information about amounts to intermediate nodes. On Liquid, payment amounts are private by default.

Simplicity: There are no channels on Liquid, no inbound liquidity to source, no rebalancing, and no node to keep online. A Liquid transaction works like a standard Bitcoin on-chain transaction: you have a balance, you send an amount to an address, and it arrives in about two minutes. The operational ceiling is dramatically lower than self-custodial Lightning.

Liquid is governed by a federation of more than 80 Bitcoin-aligned businesses, including exchanges, infrastructure companies, and asset managers, with 15 acting as active functionaries who sign blocks using an 11-of-15 multisig arrangement. These are organizations that have a direct economic interest in Bitcoin's continued success, which is a meaningful distinction from an arbitrary group of third parties. That said, this federation model does introduce a different trust assumption than Bitcoin's base layer: Liquid is not as decentralized as Bitcoin mainchain, and that tradeoff is worth understanding clearly. For the specific use case of a spending wallet holding smaller amounts for daily transactions, the tradeoff is reasonable: better privacy, lower complexity, and faster settlement than on-chain Bitcoin, without the operational overhead of self-custodial Lightning.