I don't want to run a full node yet, but I want to build an application. How and what do I use to query publicly available nodes? What nodes besides blockchain.info are publicly available for me to query over HTTP/HTTPS?
Depending on what you want to do there are several answers.
- https://longhorn.bullpay.com - Up to 2,000 Tx's returned per call
- https://live.blockcypher.com/btc/ - Up to 2,000 Tx's returned per call
These may work for you but have reduced thru put:
- https://blockexplorer.com - Up to 50 Tx's returned per call
- https://blockchain.info - Up to 50 Tx's returned per call
All these services act like a full node (at least bullpay and blockcypher have the ability to send transactions, i'm unsure about the other two in this regard). They all have free versions. Some have paid versions to increase the number of requests you can make per second for increased scalability. The links are to their explorers. API documentation can be found on each site.
So again, it depends on what you're trying to accomplish. If you're working heavily with historical data for things like auditing, you'll want to obtain more data faster. Focus on the first two. If you're just messing around then any of them would work with varying degree's of effort.
Then you can go for an api provider. There are plenty them are available out there. https://applikeysolutions.com/blog/10-best-blockchain-api-providers-for-developers