How could I make my own API to query the blockchain I'm looking to access transaction history for some specific coins directly from the blockchain. The main reason is that most of current API are not free or don't provide information for the coins I want.
I'm interested in the Bitcoin block chain but in the BSC as well. And for both I'm having issues understanding if I need to run a node myself in order to retrieve transaction or if some &quot;public&quot; node allow people to query them for information. 
On top of that, I can't find any information related to what would be the way to request information from the node, like using REST or something. 
Same goes in the case I want to run the node myself, not much information on what the exposed interface would be etc...
Doesn't anyone already tried to build his own API on a chain ?
You could use www.tatum.io to do all of that. We provide blockchain infrastructure and a simple, unified REST API that supports over 20 blockchains. You can do everything with a free plan, and upgrade to a paid plan when you need more that 5 API requests per second.