Thank you to all of repliers. The advices helped me to implement the solution:
1. Using actual rates with this API https://api.blockcypher.com/v1/btc/main
2. Using RBF to increase comission rate of "old" txes

 

Thank to all of the speakers, the information provided helped me to unrstand the way I should work, optimizing commission rate rather then consolidating inputs.

Thank you for your help. I think I need to test both, decreasing comission rate and destructuring one big tx into several smaller.

Hello, everyone

I have a problem with my application, and regarding to that I'm quite new to btc related development, I hope you can help me to figure out the right solution.

So basically, I have a payment system API, wtitten in Nest.js which works with bcoin node implemenation (https://github.com/bcoin-org/bcoin)
The node stores one master wallet and many account bind to it. The balance of wallet is splitted among accounts.

The main problem is: When I need to send a bit large amount of BTC, the inputs quantity can reach 400-500, with the corresponding
high transaction fee

How to decrease commision of such transactions? I've researched this topic and found the possible solution - make psbt's with my accounts, finalize all inputs, extract and broadcast the transaction with 1 computed input instead of 400-500, some kind of payjoin or coinjoin.

But I discovered that bcoin doesn't support psbt bip174 standard and the whole implementation is no longer maintained. I was very disappointed.

The one man from bitcoinjs-lib (https://github.com/bitcoinjs/bitcoinjs-lib) told me that I can try to use their lib to manage psbt's, and bcoin to fetch accounts, but it seems that nobody have done this kind of a fusion.
 
Does anybody worked with bcoin this way? How can I deal with this problem? Please, other solutions or any help are very appreciated. Thank you

UPD Some people proposed to use this CLI (https://github.com/payjoin/rust-payjoin) but I'm not sure about it, beacuse looks like it uses psbt's as well. How does deal with my node? And if this solution is suitable, how to implement it within Nest.js application?