[Sep 2025]Mempool empty, Consolidate your small inputs @0.15 sat/vbyte

[bitmover]

which wallets do you guys use for sub 1 sat/vB?

I created such a transaction in Electrum and broadcasted it from the mempool.space website. But to do this I had to edit the wallet.py file, specifically replacing the line #3336 (v. 4.6.0)

Code:

allow_send = False

with

Code:

allow_send = True

.

My Electrum doesn`t have wallet.py data file.

I tried to export the raw transaction clicking this button


But I couldn`t decode it in any online tool and I dont have bitcoin core installed here`.

My idea was to change the raw transaction fee, sign using electrum and then push it using https://mempool.space/tx/push

[igor72]

My Electrum doesn`t have wallet.py data file.

To access Python files, you need to use Electrum-4.6.0.tar.gz in Linux.

I tried to export the raw transaction clicking this button
But I couldn`t decode it in any online tool and I dont have bitcoin core installed here

What are you going to do with it next?

[LoyceV]

And then, after next halvings, we may have a lot more non-monetary use cases, where people will make zero satoshi inputs, zero satoshi outputs, with zero satoshi fees, and then, coinbase amounts will be low, and blockchain will no longer be used to process any payments, if 90% of the network will be focused on NFTs, and other things, and if coin amounts will be treated just like some unimportant field in legacy transaction space.

I'm not so worried about this. In the past few years, I've seen blockchain data spam pay hundreds of millions if not billions of dollars in transaction fees. It's the normal Bitcoin transactions that benefit from lower fees, not the spammers who earn from gullible victims.

How did you do that?

I'd like to know that too. I always thought Electrum used it's own format for unsigned transactions. Even coinb.in can't decode it.

[igor72]

I always thought Electrum used it's own format for unsigned transactions.

That used to be the case. Now there is standard PSBT.

[stwenhao]

How did you do that?

You can export your transaction as PSBT from Electrum, and then import as PSBT into Bitcoin Core. For example, if all coins will be sent to bc1pfeessrawgf (spendable by anyone), with 1 sat/vB:

Code:

decodepsbt cHNidP8BAEACAAAAAW2MuczyNOxtw4iTkqDYOtzLk8BIpRx0BD+IHUEuxdYCAAAAAAD9////AZDQOAAAAAAABFECTnOJ1A0AAAEAcQIAAAABtpKe6MjOeoDrAC1bBzBzLKJcd6NsBrHVwc7WLa9c7mIAAAAAAP3///8C7NA4AAAAAAAWABQTE7Z8LosXozj3bymGn9oxful5FjjJUwAAAAAAFgAU7YUScTRMlk4iiPKuh+qpQqqwO7/UuQ0AAQEf7NA4AAAAAAAWABQTE7Z8LosXozj3bymGn9oxful5FgAA
{
  "tx": {
    "txid": "419386dbb4ee7fe5b4039665f5cdcad4bd2642e05130b11cbe6c330183040b75",
    "hash": "419386dbb4ee7fe5b4039665f5cdcad4bd2642e05130b11cbe6c330183040b75",
    "version": 2,
    "size": 64,
    "vsize": 64,
    "weight": 256,
    "locktime": 906377,
    "vin": [
      {
        "txid": "02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d",
        "vout": 0,
        "scriptSig": {
          "asm": "",
          "hex": ""
        },
        "sequence": 4294967293
      }
    ],
    "vout": [
      {
        "value": 0.03723408,
        "n": 0,
        "scriptPubKey": {
          "asm": "1 29518",
          "desc": "addr(bc1pfeessrawgf)#d6x2lh3c",
          "hex": "51024e73",
          "address": "bc1pfeessrawgf",
          "type": "anchor"
        }
      }
    ]
  },
  "global_xpubs": [
  ],
  "psbt_version": 0,
  "proprietary": [
  ],
  "unknown": {
  },
  "inputs": [
    {
      "witness_utxo": {
        "amount": 0.03723500,
        "scriptPubKey": {
          "asm": "0 1313b67c2e8b17a338f76f29869fda317ee97916",
          "desc": "addr(bc1qzvfmvlpw3vt6xw8hdu5cd876x9lwj7gkrf73x8)#vrsc8xx0",
          "hex": "00141313b67c2e8b17a338f76f29869fda317ee97916",
          "address": "bc1qzvfmvlpw3vt6xw8hdu5cd876x9lwj7gkrf73x8",
          "type": "witness_v0_keyhash"
        }
      },
      "non_witness_utxo": {
        "txid": "02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d",
        "hash": "02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d",
        "version": 2,
        "size": 113,
        "vsize": 113,
        "weight": 452,
        "locktime": 899540,
        "vin": [
          {
            "txid": "62ee5caf2dd6cec1d5b1066ca3775ca22c7330075b2d00eb807acec8e89e92b6",
            "vout": 0,
            "scriptSig": {
              "asm": "",
              "hex": ""
            },
            "sequence": 4294967293
          }
        ],
        "vout": [
          {
            "value": 0.03723500,
            "n": 0,
            "scriptPubKey": {
              "asm": "0 1313b67c2e8b17a338f76f29869fda317ee97916",
              "desc": "addr(bc1qzvfmvlpw3vt6xw8hdu5cd876x9lwj7gkrf73x8)#vrsc8xx0",
              "hex": "00141313b67c2e8b17a338f76f29869fda317ee97916",
              "address": "bc1qzvfmvlpw3vt6xw8hdu5cd876x9lwj7gkrf73x8",
              "type": "witness_v0_keyhash"
            }
          },
          {
            "value": 0.05491000,
            "n": 1,
            "scriptPubKey": {
              "asm": "0 ed851271344c964e2288f2ae87eaa942aab03bbf",
              "desc": "addr(bc1qakz3yuf5fjtyug5g72hg064fg24tqwalz0h5kq)#jyhlqw6s",
              "hex": "0014ed851271344c964e2288f2ae87eaa942aab03bbf",
              "address": "bc1qakz3yuf5fjtyug5g72hg064fg24tqwalz0h5kq",
              "type": "witness_v0_keyhash"
            }
          }
        ]
      }
    }
  ],
  "outputs": [
    {
    }
  ],
  "fee": 0.00000092
}

And then, by knowing all of that, you will have enough information, to craft a different transaction from Bitcoin Core. For example:

Code:

createrawtransaction '[{"txid":"02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d","vout":0,"sequence":4294967293}]' '[{"bc1pfeessrawgf":0.03723500}]' 899540 true
02000000016d8cb9ccf234ec6dc3889392a0d83adccb93c048a51c74043f881d412ec5d6020000000000fdffffff01ecd03800000000000451024e73d4b90d00
decoderawtransaction 02000000016d8cb9ccf234ec6dc3889392a0d83adccb93c048a51c74043f881d412ec5d6020000000000fdffffff01ecd03800000000000451024e73d4b90d00
{
  "txid": "3e4f813e2db5fd97c56303e797d2618982c590583c675ec05554c1e228d7f02c",
  "hash": "3e4f813e2db5fd97c56303e797d2618982c590583c675ec05554c1e228d7f02c",
  "version": 2,
  "size": 64,
  "vsize": 64,
  "weight": 256,
  "locktime": 899540,
  "vin": [
    {
      "txid": "02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d",
      "vout": 0,
      "scriptSig": {
        "asm": "",
        "hex": ""
      },
      "sequence": 4294967293
    }
  ],
  "vout": [
    {
      "value": 0.03723500,
      "n": 0,
      "scriptPubKey": {
        "asm": "1 29518",
        "desc": "addr(bc1pfeessrawgf)#d6x2lh3c",
        "hex": "51024e73",
        "address": "bc1pfeessrawgf",
        "type": "anchor"
      }
    }
  ]
}

As you can see, it has zero fee. It is of course unsigned, but if you will sign and broadcast it, then it will be valid, if you will pass it to some miner, who will accept it. And of course, using 0.10 sat/vB is also an option, it is just a matter of calculating the proper amount. Usually, I start with zero fees, when I make my own transactions, and later, when I have everything as I want, only then I adjust amounts, to make non-zero fees out of them.

Because here, you can control everything in raw, unsafe form. If you will type "please send everything to something spendable by anyone", then it will be done. If you make a transaction with 100% fees, it will be also done. There are no protections, if you work with transactions in their raw form. If you ask Bitcoin Core to sign something invalid, or stupid, then it will produce a valid signature, as long as you will import your private keys.

And later, there are many services, which would allow you to broadcast it, when you will have your transaction in the final form. For example:

Code:

curl -X POST -sSLd "02000000016d8cb9ccf234ec6dc3889392a0d83adccb93c048a51c74043f881d412ec5d6020000000000fdffffff01ecd03800000000000451024e73d4b90d00" "https://mempool.space/api/tx"
sendrawtransaction RPC error: {"code":-26,"message":"tx-size-small"}

Here, obviously my example won't work, because I don't have your keys. But if you put it correctly in Bitcoin Core, by using "signrawtransactionwithkey", then it will be signed, whatever you will craft. For example, let's sign it with private key, equal to one:

Code:

signrawtransactionwithkey "02000000016d8cb9ccf234ec6dc3889392a0d83adccb93c048a51c74043f881d412ec5d6020000000000fdffffff01ecd03800000000000451024e73d4b90d00" '[" KwDiBf89QgGbjEhKnhXJuH7LrciVrZi3qYjgd9M7rFU73sVHnoWn"]'  '[{"txid":"02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d","vout":0,"scriptPubKey":"76a914751e76e8199196d454941c45d1b3a323f1433bd688ac","amount":0.03723500}]' "NONE|ANYONECANPAY"
{
  "hex": "02000000016d8cb9ccf234ec6dc3889392a0d83adccb93c048a51c74043f881d412ec5d602000000006a4730440220270098e563f94231f67c0b4c36df38212f38cf8a492558ee76d45c6f8a6b694e02206e9c71ec0f7729adc57cca39779c5bd4163e0052ba1a5ffb870b90d51e5f415382210279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798fdffffff01ecd03800000000000451024e73d4b90d00",
  "complete": true
}
decoderawtransaction 02000000016d8cb9ccf234ec6dc3889392a0d83adccb93c048a51c74043f881d412ec5d602000000006a4730440220270098e563f94231f67c0b4c36df38212f38cf8a492558ee76d45c6f8a6b694e02206e9c71ec0f7729adc57cca39779c5bd4163e0052ba1a5ffb870b90d51e5f415382210279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798fdffffff01ecd03800000000000451024e73d4b90d00
{
  "txid": "e052d425a3684afd512a5ad6b7cea2ed801eef75af4435b36601a588c781b146",
  "hash": "e052d425a3684afd512a5ad6b7cea2ed801eef75af4435b36601a588c781b146",
  "version": 2,
  "size": 170,
  "vsize": 170,
  "weight": 680,
  "locktime": 899540,
  "vin": [
    {
      "txid": "02d6c52e411d883f04741ca548c093cbdc3ad8a0929388c36dec34f2ccb98c6d",
      "vout": 0,
      "scriptSig": {
        "asm": "30440220270098e563f94231f67c0b4c36df38212f38cf8a492558ee76d45c6f8a6b694e02206e9c71ec0f7729adc57cca39779c5bd4163e0052ba1a5ffb870b90d51e5f4153[NONE|ANYONECANPAY] 0279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798",
        "hex": "4730440220270098e563f94231f67c0b4c36df38212f38cf8a492558ee76d45c6f8a6b694e02206e9c71ec0f7729adc57cca39779c5bd4163e0052ba1a5ffb870b90d51e5f415382210279be667ef9dcbbac55a06295ce870b07029bfcdb2dce28d959f2815b16f81798"
      },
      "sequence": 4294967293
    }
  ],
  "vout": [
    {
      "value": 0.03723500,
      "n": 0,
      "scriptPubKey": {
        "asm": "1 29518",
        "desc": "addr(bc1pfeessrawgf)#d6x2lh3c",
        "hex": "51024e73",
        "address": "bc1pfeessrawgf",
        "type": "anchor"
      }
    }
  ]
}

Is it invalid? Of course. Does it allow for anyone to grab your coins, if you use "NONE|ANYONECANPAY"? Of course. But Bitcoin Core will allow you to sign any transaction, if you just feed it with the right data. You don't need a blockchain to do that, you just need some offline instance of Bitcoin Core, and your transaction data, which you can get from Electrum, from block explorers, or from any other place.

So, my example is "invalid on purpose", but in general, if you put the right inputs and outputs, with the right amounts, with the proper sighashes, like SIGHASH_ALL, and with the proper "scriptPubKey", which in your case seems to be "00141313b67c2e8b17a338f76f29869fda317ee97916", then it should work, and be broadcastable from mempool.space, or any other block explorer.

But in general, be careful, because you don't want to save just a few satoshis on fees, only to lose 0.03723500 BTC, if you make any mistake. And try it on testnets or in regtest first, to get familiar with raw transaction handling and PSBTs, if you never did it before.

[satscraper]

Did I miss something?

mempool.space shows transactions with the fee as low as 0.1 sat/vB in candidate blocks.

f3666861f6f498a7b2075b4129f7c3e9623caa2aa94f4b4992c30090e1a84c61 is one of them with fee 0.41 sat/vB.

Did miners change their policy regarding the minimum feerate they accept for transactions to be included in the mempool?

[LoyceV]

Did I miss something?

Read the last 2 pages

[stwenhao]

Did miners change their policy regarding the minimum feerate they accept for transactions to be included in the mempool?

Some of them did, others did not. And as long as there will be a lot of transactions with higher fees, people can broadcast anything they want, including free transactions. They will be included only if mempools in mining nodes will be empty.

Also, here is some practical demonstration: https://mempool.space/tx/aba3c2ae442aa20150996ee68f9aa4da83b57a4312891078be0c2e68c50b2801

It is signed with SIGHASH_ANYONECANPAY, which means, that anyone can add more inputs, to accelerate it, without invalidating my signatures, and use full-RBF on top of what I broadcasted. Or, alternatively, anyone can use Proof of Work, to apply CPFP on top of it, and for example sweep coins from https://mempool.space/address/bc1qzsjnew5qcn75e4cqdsc6r9v8fjy5ensancqmv2l2n82p0q5f5tlsfu3slz as it was demonstrated on testnet4, for example here: https://mempool.space/testnet4/tx/8397c2323e3fa099c15be68399346b2b3d223ef8e81e553242763e1a4c60771a

This transaction is just the same puzzle, as I previously did in testnet4, but replicated on mainnet instead, and with lower amounts. There are many speculations about quantum computers recently, so I decided to make a practical example, that could show us the progress, because "OP_SHA256 OP_CHECKSIG" is just a binary signal, which would tell us, that things are broken, but won't tell us earlier, how close we are.

[NotATether]

Has the default minrelayfee in Bitcoin Core config been updated to 100 sats/KB or something?

To make it that value or lower for a newer version of Bitcoin Core is the only way that these sub-1sat transactions would be allowed to propagate, or else they would have been discarded by the nodes.

That, or Bitcoin Knots made that adjustment.

[satscraper]

Has the default minrelayfee in Bitcoin Core config been updated to 100 sats/KB or something?

To make it that value or lower for a newer version of Bitcoin Core is the only way that these sub-1sat transactions would be allowed to propagate, or else they would have been discarded by the nodes.

That, or Bitcoin Knots made that adjustment.

I believe miners are free to set the minrelayfee themselves, and their reasoning for choosing the particular low value is based on the assumption that it's better to mine the chock-full blocks rather than half-empty ones. That's why we're currently seeing blocks filled with those sub-1 sat/vB transactions. One of such block is 906805 which is filled with the sub-1 sat/vB transactions containing inscriptions.

[Pmalek]

Has anyone had any success in finding a server on Electrum, Sparrow, or another popular wallet that supports broadcasting of transactions that pay below 1 sat/vByte? Besides Blue Wallet, have other software clients signaled that they will make changes in this regard?

I don't think manually editing raw transactions and exporting and importing from Electrum to Bitcoin Core is something many people would be interested in doing. It seems that's the only option for now.

[LoyceV]

Has anyone had any success in finding a server on Electrum, Sparrow, or another popular wallet that supports broadcasting of transactions that pay below 1 sat/vByte?

Nope. I considered upgrading my VPS and adding 1 TB storage to run my own Electrum server, but my webhost "expects new stock in September". I don't really want to delete this data to free up some space either. I don't want an expensive server for this, as it's an annual recurring cost to keep it running. Just paying 1 sat/vbyte is probably cheaper, lol.

[satscraper]

Has anyone had any success in finding a server on Electrum, Sparrow, or another popular wallet that supports broadcasting of transactions that pay below 1 sat/vByte? Besides Blue Wallet, have other software clients signaled that they will make changes in this regard?

You might want to try using Bitcoin Core with the following entry in your bitcoin.conf file:

Code:

mintxfee=<your_desired_fee>

If you're using Bitcoin Core not only as a wallet but also as the full node consider adding the following as well:

Code:

minrelaytxfee=<your_value>

P.S. I've noticed that transactions with fees below 1 sat/vB are becoming increasingly common, which definitely  is the nice move but most of low-fee-rate  trxs are from the inscription-spammers.

[FinneysTrueVision]

I prefer trezor but Electrum is good, trezor should do an upgrade in the firmware and drop fee level a bit.

As time goes on there are issues of sats being too high. Allowing 0.5 to 0.9 and rounding the full fee works.

Ie : 112x.9= 100.8 round it to 101

Even though Trezor says the minimum is 1 sat/vB, if you type a lower amount and wait a few seconds it will actually create a valid transaction. Here I created a transaction with 0.5 sat/vB fee. If you’re connected to their backend, they enforce a higher minimum relay fee so it would get rejected but you can broadcast the raw hex on mempool.space.

[philipma1957]

I prefer trezor but Electrum is good, trezor should do an upgrade in the firmware and drop fee level a bit.

As time goes on there are issues of sats being too high. Allowing 0.5 to 0.9 and rounding the full fee works.

Ie : 112x.9= 100.8 round it to 101

Even though Trezor says the minimum is 1 sat/vB, if you type a lower amount and wait a few seconds it will actually create a valid transaction. Here I created a transaction with 0.5 sat/vB fee. If you’re connected to their backend, they enforce a higher minimum relay fee so it would get rejected but you can broadcast the raw hex on mempool.space.

Nice work I will check this out.

[joker_josue]

Has anyone had any success in finding a server on Electrum, Sparrow, or another popular wallet that supports broadcasting of transactions that pay below 1 sat/vByte?

Nope. I considered upgrading my VPS and adding 1 TB storage to run my own Electrum server, but my webhost "expects new stock in September". I don't really want to delete this data to free up some space either. I don't want an expensive server for this, as it's an annual recurring cost to keep it running. Just paying 1 sat/vbyte is probably cheaper, lol.

I have the full node on my home PC, so I'm considering configuring Electrum to that node, which will increase privacy and allow for these extra settings. But, I haven't dedicated time to it yet, as soon as I have some time I will do it and share the experience.

When are you planning on paying for this 1TB?

[LoyceV]

I have the full node on my home PC, so I'm considering configuring Electrum to that node, which will increase privacy and allow for these extra settings. But, I haven't dedicated time to it yet, as soon as I have some time I will do it and share the experience.

With "connect", you mean install Electrum server, right?

When are you planning on paying for this 1TB?

Unless I find a good offer, it looks like it's going to be after September. By then other Electrum servers may have lowered the minimum, so I may not need to do it anymore.

Yesterday fees went up, now they're back at under 1.00 sat/vbyte:

(source)

[joker_josue]

I have the full node on my home PC, so I'm considering configuring Electrum to that node, which will increase privacy and allow for these extra settings. But, I haven't dedicated time to it yet, as soon as I have some time I will do it and share the experience.

With "connect", you mean install Electrum server, right?

I have Bitcoin Core running the node, now I have to make it connect to Electrum, that is, install the Electrum Server. Since I'm on Windows, the process is a bit more complex. But it's just a matter of dedicating some time to it.

Unless I find a good offer, it looks like it's going to be after September. By then other Electrum servers may have lowered the minimum, so I may not need to do it anymore.

Incidentally, I've also thought about setting up a node on a server (some project ideas). If you find something later and want to exchange ideas, let me know. 

[LoyceV]

Incidentally, I've also thought about setting up a node on a server (some project ideas). If you find something later and want to exchange ideas, let me know.  

Maybe all I need is a TB somewhere that I can mount using SSHFS. I'd only place Bitcoin Core's blocks directory on there. That works fine if it's a local HDD, so I assume a network share would work too. But I have no idea what bandwidth that would take for running Electrum server.
Somehow I always find myself short on disk space and bandwidth.

[joker_josue]

Incidentally, I've also thought about setting up a node on a server (some project ideas). If you find something later and want to exchange ideas, let me know.  

Maybe all I need is a TB somewhere that I can mount using SSHFS. I'd only place Bitcoin Core's blocks directory on there. That works fine if it's a local HDD, so I assume a network share would work too. But I have no idea what bandwidth that would take for running Electrum server.
Somehow I always find myself short on disk space and bandwidth.

I'll look into this to understand what might be involved. Then I'll share some insights with you; they might be interesting.