Keysend

Keysend is a Lightning Network feature that lets one node push a payment directly to another node's public key without the recipient first issuing an invoice. It inverts the normal request-then-pay flow: instead of the payee generating a payment hash and waiting, the payer generates the secret themselves and ships the funds spontaneously to a known node ID.

How it works

In a standard Lightning payment, the recipient creates a random preimage, hashes it into the invoice's payment hash, and only reveals the preimage when paid. Keysend reverses ownership of that secret: the sender creates the preimage and tucks it into the encrypted onion packet inside a custom TLV (type-length-value) record carried to the final hop. When the payment arrives, the recipient's node reads the preimage out of the payload and uses it to claim the funds, since it matches the payment hash the HTLC was built around.

Uses and limitations

Because no prior coordination is needed, keysend powers streaming and push payments. It is the backbone of Podcasting 2.0 and value-for-value models, where listeners stream sats to a creator's node continuously without generating invoices. The main drawback is that the sender, not the receiver, produces the preimage, so the payer loses the cryptographic proof-of-payment that a normal invoice gives them, and the receiver has no built-in record of what the payment was for.

Keysend is the spontaneous-payment counterpart to the structured flows in BOLT12 (Offers). Both rely on the same onion-routed HTLC machinery underlying Lightning.