I implemented a very simple decentralized transaction monitoring app called TxMon, available here:
https://reqrypt.org/txmon.htmlTxMon displays transaction and related information real-time. Using the
--verbose option, TxMon also displays additional information such as node statistics and transaction rates. See the above link for a visual demo.
TxMon is an application (program), and is not "web-based". TxMon is in some ways better than most web-based "block explorers" in that (a) it displays the complete transaction rather than just the hash, and (b) it is decentralized in that you connect directly with the Bitcoin network rather than going through a third party. TxMon therefore provides a much more accurate snapshot of current network activity.
TxMon is based on the
PseudoNode project. This means that TxMon inserts itself as a "pseudo" full node into the network, and participates in network activities such as transaction and block relaying (using network heuristics rather than full-node verification). This means that TxMon can connect with the network and "sync" near instantly, without downloading the blockchain. It also means that TxMon is not simply leeching bandwidth from the network, i.e. it also contributes bandwidth.
The source code for TxMon is part of the PseudoNode repository (under apps/txmon):
https://github.com/basil00/PseudoNodeTxMon was implemented for my own amusement, but others may find it useful too.
