Sadly, XRB (Raiblocks, formally) was designed that way. Instant, fee-less. Problem was, there were races and some bugs, which caused a lot of reconciliation pr

Sadly, XRB (Raiblocks, formally) was designed that way. Instant, fee-less. Problem was, there were races and some bugs, which caused a lot of reconciliation problems for exchanges that listed it. It dropped after 2017, and AFAIK, is essentially a dead coin.