live API

Write a message on the Bitcoin blockchain

Permanently, in an OP_RETURN output. In minutes.

SatWire needs JavaScript: your message is priced, and any picture is resized and encoded, in your own browser before anything is sent. Nothing is uploaded until you choose to publish.

sats

Optional. SatWire publishes your message — this only adds a payment on top.

Show on the wall

slower faster

2,220 sats

Network fee: 220
Service fee: 2,000
To recipient: 0

On the wire

What SatWire does

SatWire writes your message into the Bitcoin blockchain itself. Not a link to it, not a hash of it — the text, in an OP_RETURN output of a real Bitcoin transaction, where it stays as long as Bitcoin does. You get the transaction id and can check it in any block explorer.

There is no account and no signup. You type a message, we quote a price, you pay a one-off address, and the transaction is broadcast. You can publish a picture the same way: it is resized and re-encoded to WebP in your own browser, so the original file never leaves your device and its GPS data never goes anywhere. The bytes that reach the chain are a complete, valid image file — anyone can pull them out of the transaction and open them, with no tool of ours.

What it costs

Two parts: a flat 2,000-sat service fee, and the Bitcoin network fee for the transaction. The network fee depends on how big your message is and how fast you want it confirmed — a short line of text costs about 220 sats to publish, a picture costs more because it is bigger.

Roughly, at the cheapest fee rate, service fee included
What you publish	On-chain size	Total
A line of text	~100 bytes	~2,220 sats
Picture, 160×120	~1,500 bytes	~5,250 sats
Picture, 256×192	~2,840 bytes	~7,930 sats
Picture, 512×384	~7,880 bytes	~18,000 sats
Picture, 1024×768	~20,000 bytes	~42,250 sats

The limits are 1,000 bytes for text and 20,000 bytes for a picture. The composer above shows the exact price before you pay anything.

How it works

Write your message, or attach a picture and pick a budget.
You get a Bitcoin address and an exact amount.
You pay it. Nothing else is required of you.
SatWire builds a transaction carrying your bytes and broadcasts it.
You get the transaction id, and the message is on the chain forever.

Questions

Can anyone read what I publish?: Yes. The Bitcoin blockchain is public, and so is everything written into it. Do not publish anything you would not put on a billboard.
Can I delete it later?: No. Nobody can — not you, not us. That is the point of it, and the reason to think before you pay. Showing your message on the public wall here is a separate choice, and that one the operator can undo.
Do I need an account or a wallet connection?: Neither. You pay from any Bitcoin wallet to an address we show you once.
How long does it take?: The transaction is broadcast within seconds of your payment arriving. How long it then takes to be mined into a block depends on the fee rate you chose.
What if it cannot be published?: The payment is sent back to the address it came from, automatically. In the rare case that is not possible, the operator is alerted and sorts it out by hand.
Can other software read my picture, or only SatWire?: Any software. There is no wrapper and no format of our own — the data in the OP_RETURN is the image file itself, so a hex decode is enough.

API

A small HTTP API for publishing to the Bitcoin blockchain without the composer. No key is needed for the public endpoints.

POST

/api/message-request Returns an address to pay. Body: message, and optionally targetAddress, amountToSend, feeRate, isPublic.

GET

/api/request-status/:idPoll a request.

DEL

/api/request/:idCancel, while unpaid.

GET

/api/wallMessages customers chose to show publicly.

GET

/api/payment-qr.svg?requestId=A BIP21 code for an open order.