Asynchronous Payments

Asynchronous payments are payments that complete even when the sender and recipient are not online at the same time. On bitcoin's base layer this is automatic, since the blockchain holds funds for any address indefinitely. On the Lightning Network, where both parties normally must be reachable, it requires special protocol design.

Why it matters

Lightning's requirement that a recipient be online to claim a payment is a genuine obstacle for mobile wallets, which spend most of their existence asleep in a pocket. Asynchronous payment proposals address this by letting an intermediate node hold an in-flight payment until the recipient reappears, using cryptographic guarantees rather than trust to ensure the funds can only be claimed by the intended party. Related work on trampoline routing and offers aims at the same goal: making self-custodial Lightning behave like an always-on account without becoming one.

How it works

In the leading designs, the sender's payment is locked with a secret only the recipient can reveal, and a forwarding node holds the locked payment rather than completing it immediately. When the recipient's wallet comes online, it presents the secret, the payment settles atomically along the whole route, and the sender receives cryptographic proof of delivery. If the recipient never appears before the lock's timeout, the funds return to the sender automatically. The pattern extends bitcoin's core promise, settlement without trusted intermediaries, to a world of intermittently connected devices.