publicly available json-rpc node for bitcoin-cli connection There is a service provided by blockchain.info described on json_rpc_api page.
More or less it describes the API that user can use to access their blockchain similar way as using bitcoin-cli to own daemon.
It usage is currently demonstrated as:

$ ./bitcoin-cli -rpcconnect=rpc.blockchain.info -rpcport=443 -rpcssl -rpcuser=YourWalletIdentifier -rpcpassword=YourPassword getinfo


It looks nice but there is an information on the site which states:


  From the 1st December 2014, in order to use this API, access must be explicitly enabled, and all client ip addresses whitelisted by the wallet owner. Manage access in [Account Settings] -> [IP Restrictions] 


And that's the problem, because I'm interested just into fetching some block or transaction details. I don't need any RPC which would require authorization. I don't even want to create an account.
So the question is:
Are there any free services (or maybe it is still available on blockchain.info somehow?) which allows to use JSON-RPC against their bitcoin daemon?
I don't care about the speed or waiting 10 seconds between each call etc.
There is a free bitcoin-cli sandbox at bitcoindev.network:


  Here is a simple sandbox environment for trying out the bitcoin command line interface! Select Start Scenario to bootstrap your own private instance! 


You can check out the on-line sandbox here:

https://bitcoindev.network/bitcoin-cli-sandbox/

Simultaneously they provide a docker container for it, so your students can go up &amp; running with their own daemon in a blink of an eye.