ProfEduStream
Welcome to PlanB.network! I'm Thomas, a.k.a. @ProfEduStream, and I first became interested in Bitcoin through mining. Subsequently, having familiarized myself with data analysis and Python, I quickly became interested in on-chain analysis; particularly in the analysis of transactions from blocks 1 to 210000. In 2023, I began writing articles titled "Bitcoin Blockchain Fun Facts" on my Substack. In parallel, as a teacher, I have a deep passion for sharing my knowledge. This is why I co-created the Bitcoin Lille association in France, with which we hold a weekly meet-up. There, I regularly give presentations, both technical and simplified, which are all available open-source on YouTube and my Substack. Finally, I try to bring together communities, both French and international. Because together, we will go much further, much faster.
Normally, when you sign a transaction, it is automatically broadcast to every Bitcoin node on the network. It then waits to be mined.
However, for as long as it is not in a block, an attacker who has obtained your private key could replace it and steal the funds. This is typically the case if you use a ColdCard hardware wallet.
The Slipstream tool from the mining company MARA lets you bypass broadcasting the transaction to the network: it is sent directly (and only) to a miner, which keeps it private and avoids exposing it on the network. The transaction will probably take longer to be mined, but it will be protected against a replacement attack.
Below, we offer a tutorial allowing users of Liana, as well as users of the Sparrow wallet, to use miner MARA's Slipstream tool through the outofband.wizardsardine.com page.
⚠️ Warning: this tool is only meant for certain profiles, mainly Liana wallets, miniscript wallets and some types of multisig. Wizardsardine explicitly advises against using it for wallets whose funds are already at critical risk of theft, for example those whose recovery phrase was generated on a ColdCard device affected by the random number generator vulnerability. In that situation, the race against the attacker is a matter of seconds, and a transaction sent to a single miner takes far longer to confirm than a normally broadcast one. If this concerns you, read our dedicated tutorial first:
For Liana users
Liana is maintained by Wizardsardine, the publisher of the outofband.wizardsardine.com page, so the path is direct: you simply export the signed PSBT file instead of broadcasting it.
Prerequisite: have funds on your Liana wallet.
Step 1: Create your transaction with Liana
As usual, build your transaction by adding the destination address, the description, and the amount (here, the maximum available in the wallet).
To set the fee rate:
- select the coins you want to spend by clicking the small box at the bottom left, under "Coins selection";
- then enter the fee rate. Remember to set fees much higher than the suggested rate, as described on this page: outofband.wizardsardine.com.
Finally, click "Next".
Step 2: Check your transaction details
Before clicking "Sign", check your transaction details; in particular:
- the amount sent;
- the number of satoshis allocated to transaction fees;
- but above all, the address you are sending the funds to (remember to check the first 5/6 characters, the last 5/6, and 5/6 characters in the middle of the address in order to avoid "address poisoning" attacks).
Step 3: Select the signing wallets
Next, select the software and/or hardware wallets you need to sign your transaction with. A quick reminder: in the case of a 2-of-2 multisig wallet, you need 2 signatures out of 2.
Step 4: Export your transaction's PSBT file
The Bitcoin transaction is now signed by the appropriate keys. Do not click "Broadcast", otherwise it will be shared with the entire network and, if you use a ColdCard hardware wallet, your transaction will be publicly exposed and your funds will be at risk.
You can now click "Export", then save the PSBT file locally on your computer.
Step 5: Send the transaction to the miner via outofband.wizardsardine.com
Now for the final steps. To send the transaction to the miner, all you have to do is take the PSBT file and drag and drop it into the designated area.
The transaction is then displayed as shown below.
Step 6: Send the transaction via Slipstream
Finally, all you have to do is click "Send" so that the transaction is sent to MARA via Slipstream.
Within a few seconds, the transaction then goes from "Sending" to "Accepted":
All that is left is to copy the transaction identifier (TXID), then paste it into mempool.space in order to watch it being mined:
Please note: the transaction will show as "Transaction not found" until the miner, MARA, mines a block and includes your transaction in it. This can take several tens of minutes, or even hours, because MARA only holds around 4.5% of the Bitcoin network's hash rate. As of 4 August 2026, this corresponds to roughly one block mined every 3 hours and 45 minutes.
For users of other wallets
If you do not use Liana but still want to use the tool, here is a tutorial using a 2-of-2 multisig wallet. To do this, we will use the Sparrow software wallet.
Prerequisite: have funds on your Sparrow wallet.
Step 1: Create your transaction
With Sparrow, create the transaction on your multisig wallet. Remember to set fees much higher than the suggested rate, as described on this page: outofband.wizardsardine.com.
Once created, click "Create Transaction".
Step 2: Finalize your transaction
In order to finalize your transaction, you now need to sign it. To do this, click "Finalize Transaction for Signing".
Step 3: Sign your transaction with your different keys
Now comes the time to sign the transaction. To do this, simply sign it with the software or hardware wallet(s) you use.
Step 4: Download the signed transaction, and do not broadcast it to the network
The Bitcoin transaction is now signed by both keys of our 2-of-2 multisig. Do not click "Broadcast Transaction", otherwise it will be shared with the entire network and, if you use a ColdCard hardware wallet, your transaction will be publicly exposed and your funds will be at risk.
Step 5: Display the signed transaction script, or download the PSBT file
To display the signed Bitcoin transaction, now click "View Final Transaction". You can then copy the signed Bitcoin transaction script:
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
If you want to download the transaction file, you can either:
- click "File", then "Save transaction…";
- or click the network connection button at the bottom right (yellow button), then click "Save Final Transaction".
The transaction will then be saved locally on your computer.
Step 6: Send the transaction to the miner via outofband.wizardsardine.com
Now for the final steps. To send the transaction to the miner, all you have to do is:
- go to outofband.wizardsardine.com;
- paste the signed transaction script copied in the previous step, then click "ADD TO QUEUE" below;
- or take the file and drag and drop it into the designated area.
The transaction is then displayed as shown below.
If a message tells you that the total input amount of satoshis in your transaction is unknown (and that, as a result, the number of satoshis for the fees cannot be computed), you simply need to enter the total input amount of satoshis manually. To find it, just click on the display of your transaction in Sparrow, in the middle of the diagram:
Then enter that amount (15,904 sats in our example) into the outofband.wizardsardine.com tool:
Finally, check that the fee rate is correct.
Step 7: Send the transaction via Slipstream
Finally, all you have to do is click "Send" so that the transaction is sent to MARA via Slipstream.
Within a few seconds, the transaction then goes from "Sending" to "Accepted":
All that is left is to copy the transaction identifier (TXID), then paste it into mempool.space in order to watch it being mined:
Please note: the transaction will show as "Transaction not found" until the miner, MARA, mines a block and includes your transaction in it. This can take several tens of minutes, or even hours, because MARA only holds around 4.5% of the Bitcoin network's hash rate. As of 4 August 2026, this corresponds to roughly one block mined every 3 hours and 45 minutes.
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This tutorial has been written by ProfEduStream
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