Query publicly available full nodes 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. 

Top 2:


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.