how can i coding wallet to build exchange to client withdraw i want to build a cryptocurrency exchange so my question how is best way and secure way to depositing and withdrawing clients ?

should i use api like https://cryptoapis.io or https://www.blockcypher.com/ ?

and this api dont support tether too !!?
The most secure way is running your own full nodes per Blockchain.

Using third-party services such as blockcypher will put you &amp; your business at high risk because of:


You're giving the keys to your home &amp; revealing the password of your bank account to someone else! Because in order to use such services, they are the one who make the public &amp; corresponding private keys for you. Even though particularly Blockcypher claims that they will never store your keys, relying on it (I'm not blaming them!) is a risky approach by design!
You won't be able to participate in verifying transactions on your own &amp; maybe you're part of some attack (e.g. 51% attack even though its very unlikely).
You're centralizing the technology that has come into existence for the sake of decentralization!


If there was high costs or too steep learning curve on running your own full nodes &amp; connecting to, Maybe using provided interfaces (e.g. JSON/RPC for bitcoincore) was a reasonable way to start with, &amp; switch to your own nodes during next steps, But as there is no such barrier, you'd better launching your own nodes.