The neptune-core program comes with both a CLI interface for interacting with the program, and with an RPC server. But you can also get information about the blockchain without running neptune-core.

Both available block explorers that I know of offer some services through a HTTP/JSON interface.

Documentation of the API of the internally developed block explorer can be found on the front page: https://neptunefundamentals.org/.

As an example, you can get the digest of the current tip with a GET request to https://neptunefundamentals.org/rpc/block_digest/tip.

curl -s https://neptunefundamentals.org/rpc/block_digest/tip
"6081b4799f46350ba33405f81c57647c971327b24e6c0241e89b91c64b6ea18d9274020000000000"

The block explorer developed by an external team has their API documented here. You can, for example, get an overview of the network state through

curl 'https://neptune.vxb.ai/api/overview'
{"message":"","overview":{"average_block_time":581.71326,"block_hash":"6081b4799f46350ba33405f81c57647c971327b24e6c0241e89b91c64b6ea18d9274020000000000","cumulative_proof_of_work":"116021393513180138","day_reward":"19072000000000000000000000000000000","height":4611,"network_speed":"93543182191","proof_target":"59422205698320","timestamp":"Fri, 14 Mar 2025 17:05:27 +0800","total_fee":"567518114400000011349411601848991744","total_reward":"1421696000000000000000000000000000000","utxo_count":19172},"success":false}