<p>I work with obviously unspendable addresses. Send any one single line from a thin client, phone.  Use a core node to bundle long messages with sendmany.   <img src="https://i.sstatic.net/lkjL1.png" alt="Dogecoin example"></p>

<p><a href="https://live.blockcypher.com/doge/tx/63de9f4da10693813c977e895dafff0ae725ff9011c76d90f483c6243890ebb6/" rel="nofollow noreferrer">https://live.blockcypher.com/doge/tx/63de9f4da10693813c977e895dafff0ae725ff9011c76d90f483c6243890ebb6/</a></p>

<p>This message goes on for 83 addresses and includes a real address, which causes the wallet on my phone to complain, but still worked. </p>

CC BY-SA 4.0
2019-12-12T13:50:45.877Z
2019-12-12T14:22:28.347Z
2019-12-12T14:22:28.347Z
John Rigler
<blockquote>
  <p>So is it one OP_RETURN parameter for each bitcoin transaction or per
  each input/output address?</p>
</blockquote>

<p>One OP_RETURN output per transaction regardless of the number of inputs and outputs is standard for 0.9.x bitcoin core clients.</p>

<blockquote>
  <p>If its each transaction, so its safe to say its about .0001 btc to
  send 40 byte message?</p>
</blockquote>

<p>Yes, but you should not do it without significant reasons.</p>

<blockquote>
  <p>Aside from OP_RETURN message attachment, what other methods are there
  to attach custom data?</p>
</blockquote>

<p>There are different methods. You can use fake public keys in bare multisig outputs. Or encode some data with values or addresses of other outputs.</p>

CC BY-SA 3.0
2015-01-19T15:47:55.390Z
2015-01-19T15:47:55.390Z
amaclin
<blockquote>
  <p>Aside from OP_RETURN message attachment, what other methods are there to attach custom data?</p>
</blockquote>

<p>IP Transactions can do that. BIP0070 will probably be able to do that.</p>

CC BY-SA 3.0
2015-01-19T16:17:29.970Z
2015-01-19T16:17:29.970Z
Nick ODell
<blockquote>
  <p>Which desktop / mobile wallets support adding a custom OP_RETURN message? (ex. attach a short url link)</p>
</blockquote>

<p><a href="https://coinb.in/#newTransaction" rel="nofollow noreferrer">Coinb.in</a></p>

<p>New -> Transaction -> Advanced Options</p>

<pre><code>Null Data (80 byte limit, 40 bytes recommended)

Allow data to be sent within the transaction and stored in the blockchain by using OP_RETURN.

When using this option you may enter a hex string or address into the address field on the output tab.
</code></pre>

CC BY-SA 4.0
2019-05-06T23:05:52.987Z
2019-05-06T23:05:52.987Z
Stephen Gornick
<p>I see that many new Bitcoin 2.0 apps are making use of the additional OP_RETURN parameter for attaching data. I see that max limit is 40 bytes or roughly 40 characters? My question now regarding OP_RETURN is:</p>

<ul>
<li><p>So is it one OP_RETURN parameter for each bitcoin transaction or per each input/output address? If its each transaction, so its safe to say its about .0001 btc to send 40 byte message?</p></li>
<li><p>Which desktop / mobile wallets support adding a custom OP_RETURN message? (ex. attach a short url link)</p></li>
<li><p>Aside from OP_RETURN message attachment, what other methods are there to attach custom data?</p></li>
</ul>

CC BY-SA 4.0
2019-05-06T23:07:59.140Z
Since the time this was first posted, the limit has been increased to 80 bytes
Stephen Gornick
<client><message><mobile><op-return>
Wallets that support 40 byte message attachment via OP_RETURN? Desktop / Mobile?
Patoshi パトシ
# Wallets that support 40 byte message attachment via OP_RETURN? Desktop / Mobile?

(Asked by: username_0 on 2015-01-19)

I see that many new Bitcoin 2.0 apps are making use of the additional OP\_RETURN parameter for attaching data. I see that max limit is 40 bytes or roughly 40 characters? My question now regarding OP\_RETURN is:

* So is it one OP\_RETURN parameter for each bitcoin transaction or per each input/output address? If its each transaction, so its safe to say its about .0001 btc to send 40 byte message?
* Which desktop / mobile wallets support adding a custom OP\_RETURN message? (ex. attach a short url link)
* Aside from OP\_RETURN message attachment, what other methods are there to attach custom data?

**Tags:** client, message, mobile, op-return

> **Comments:**
> **username_1**: Since the time this was first posted, the limit has been increased to 80 bytes  

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## 4 answers

### Answer by username_2 on 2019-12-12. Score: 1 | Accepted answer

I work with obviously unspendable addresses. Send any one single line from a thin client, phone. Use a core node to bundle long messages with sendmany. ![Dogecoin example](https://i.sstatic.net/lkjL1.png)

<https://live.blockcypher.com/doge/tx/63de9f4da10693813c977e895dafff0ae725ff9011c76d90f483c6243890ebb6/>

This message goes on for 83 addresses and includes a real address, which causes the wallet on my phone to complain, but still worked.


---

### Answer by username_3 on 2015-01-19. Score: 3

> So is it one OP\_RETURN parameter for each bitcoin transaction or per
> each input/output address?

One OP\_RETURN output per transaction regardless of the number of inputs and outputs is standard for 0.9.x bitcoin core clients.

> If its each transaction, so its safe to say its about .0001 btc to
> send 40 byte message?

Yes, but you should not do it without significant reasons.

> Aside from OP\_RETURN message attachment, what other methods are there
> to attach custom data?

There are different methods. You can use fake public keys in bare multisig outputs. Or encode some data with values or addresses of other outputs.


---

### Answer by username_4 on 2015-01-19. Score: 2

> Aside from OP\_RETURN message attachment, what other methods are there to attach custom data?

IP Transactions can do that. BIP0070 will probably be able to do that.


---

### Answer by username_1 on 2019-05-06. Score: 1

Which desktop / mobile wallets support adding a custom OP_RETURN message? (ex. attach a short url link)

Coinb.in
New -> Transaction -> Advanced Options
Null Data (80 byte limit, 40 bytes recommended)

Allow data to be sent within the transaction and stored in the blockchain by using OP_RETURN.

When using this option you may enter a hex string or address into the address field on the output tab.


---

