Signet Testnet3 and Testnet4 (getblocktemplate and submitblock usage)

Hey folks, I'm digging into the Signet testnets, specifically testnet3 and testnet4, and I've got a few questions about using the getblocktemplate and submitblock RPC methods. Free RPC Nodes: Does anyone know of any free RPC nodes or API services that work with the Signet testnet? I need some reliable ones to test my setup. Using RPC Methods: I'd love some tips or examples on how to effectively use the getblocktemplate and submitblock methods in the Signet testnet environment. Are there any particular parameters or settings I should keep in mind? I'm currently working on some mining software with a focus on these Signet testnets. Any advice would be super helpful! Thanks a bunch for your help! Cheers, Just to add: I know how to build the block header and kick off the mining process... I just really need those free RPC nodes or API services for getblocktemplate and submitblock.

Neither testnet3 nor testnet4 are signets. Are you working with a custom signet, or with testnet3, or with testnet4?

If you're speaking about "testnet4", you can easily setup your own node within an hour since its blockchain isn't that big and most blocks aren't full. That's given that you have a good hardware. Just start bitcoind and bitcoin-cli with --testnet4 arg when you start your node and issue commands. The issue of public RPC nodes is they aren't willing to allow the public to use those types of commands (submitblock in your case) since it can ruin their node's ban score. So most of them just blacklists such command. Example, those commands are blacklisted in the public mainnet demo of this repo: github.com/janoside/btc-rpc-explorer That repo's live demos used to have a working testnet and signet versions but for some reason, both are not accessible but AFAIK those are also blacklisted there.