I guess the Casascius Bitcoin Analyzer site simply checks whether a Casascius address had an outgoing transaction.
Thanks for your reply.
This is what I need. How do I check if a specific address (that I know) had an outgoing transaction?
You need to build a block sniffer and create an sql database of all used keys, then updated the database for each mined blocks.
there are a few github repos, just use search, but most likely you could build your own, using python.
like this https://github.com/alext234/rpc-sniffer
you can also read more on this page
https://en.bitcoin.it/wiki/Raw_Transactions#listunspent_.5Bminconf.3D1.5D_.5Bmaxconf.3D999999.5D
Ideally you would set up your own full node with the full chain, run a block parser to create an preferably sql database of all txs and then update it whenever a new block is mined.
/KX
