Question 1

What is a Bitcoin OP_RETURN message?

Accepted Answer

OP_RETURN is a Bitcoin script opcode that lets you attach a small amount of arbitrary data, up to about 80 bytes of text, to a transaction. Once the transaction confirms, that message is stored permanently on the Bitcoin blockchain and can never be edited or deleted.

Question 2

How do I write a message on the Bitcoin blockchain?

Accepted Answer

Type your text (or fetch a Bible verse), pay the Lightning invoice, and poststr builds and broadcasts a Bitcoin transaction with your message in an OP_RETURN output. The message is inscribed on-chain within a block or two.

Question 3

Is an OP_RETURN message permanent?

Accepted Answer

Yes. OP_RETURN data is written into the Bitcoin blockchain itself, so the message is immutable and permanent. It is replicated across every Bitcoin node worldwide and cannot be removed.

Question 4

How much data can an OP_RETURN message hold?

Accepted Answer

A standard OP_RETURN output carries up to 80 bytes of data, which is roughly 80 characters of plain text. poststr shows your message size in real time so you stay within the limit.

Write a Bitcoin OP_RETURN message forever

Recent OP_RETURN messages on Bitcoin