What is Bitcoin?

Bitcoin is a digital decentralized unstoppable form of money that you can buy, sell and exchange directly, without an intermediary like a bank. It uses peer-to-peer technology to operate with no central authority; managing transactions and the issuing of bitcoins is carried out collectively by the network. Bitcoin is open-source; its design is public, nobody owns or controls Bitcoin and everyone can take part. You can learn more on bitcoin.org.

What is Bitcoin Lightning?

The Lightning Network is a layer built on top of Bitcoin. It allows for faster payments by processing transactions away from the main blockchain - while keeping the same decentralization and security. You can learn more on lightning.network.

What is a Bitcoin Lightning Address?

It looks like a regular email address (e.g. lightning@settleup.io) but you can send lightning payments to it. Normally if you want to send a lightning payment the recipient first has to generate an invoice which you then pay with your wallet. When you have a lightning address others can send payments to it anytime without you having to generate an invoice first. See more here.

How does it work in Settle Up?

In Settle Up you can settle your debts via the Lightning Network. There are two possible flows we support:

1. Recipient has a lightning address filled in their profile in the app
2. Recipient doesn't have a lightning address

When the recipient has a lightning address we simply let you pay directly to it. No extra fees (other than the network fees), no involvement of the Settle Up node, you pay directly the person you owe. If the recipient doesn't have a lightning address you will send the payment to us and we'll forward the recipient a link where they can in turn withdraw these funds into their own wallet. They will also see the pending payment in their app. There is a small fee which we charge the sender, this is displayed transparently before the initial payment is made. The recipient doesn't pay any fees. If the recipient doesn't claim the payment we will

1. Send the payment back to the original sender, if they have a lightning address filled in their profile
2. Issue the original sender a dedicated link where they can take the payment back, if they don't have a lightning address

Which wallet should I use?

There are many Lightning wallets you can choose from. There are 2 categories - custodial and non-custodial.

• Custodial wallets (e.g. Wallet of Satoshi) are typically very easy to use but you are not the real owner of your funds - the wallet operator is, it acts like your bank. They are therefore great for small amounts. Some of them also give you a lightning address out of the box.
• Non-custodial wallets (e.g. Phoenix) might be slightly more complex but you are in complete control of your funds - you don't need to trust anyone else, not even the wallet developers.

Other wallets you can choose from include Muun, BlueWallet, Breez, Zeus or LNBits. See more wallets on this list. Or you can run your own Bitcoin node (e.g. on Raspberry Pi) and connect your mobile wallet to it.