Sandbox vs Live

SDK can be configured with mode=sandbox or mode=live. There are really no differences regarding the final endpoint which will be used: https://api.blockcypher.com

Both modes were introduced to allow different configurations for the SDK depending on if you are doing tests or not.

For example, sandbox mode allows to set the log level to DEBUG and it will log all headers, request and responses.

In the future sandbox mode could be used to allow working with the API with no efect on the real account (e.g. creating new fake webhooks).

If you want to test the API with no real transactions payments you can use tesnet chain.