Zcash Blockchain Explorer https://www.instapaper.com/p/16800704 So, if there is a large number of transactions in the mempool and you paid a comparatively low transaction fee, your transaction can remain unconfirmed for an prolonged period of time since miners/validators will find transactions with higher service fees to start with. TraceHawk can be https://numberfields.asu.edu/NumberFields/show_user.php?userid=6213549