How can I send bitcoins without waiting for at least 1confirmation? I'm making a service that is similar to markets so I sometimes need to make users send bitcoins without waiting for one confirmation.
So I'm considering how markets that deal cryptocurrencies solve the problem.
Most markets run a centralized server that keeps track of user accounts, and then only submits transactions to the bitcoin blockchain when a user withdraws their funds (or the move coins internally, etc). This model leaves the user with more risk (the exchange gets hacked and they lose their coins), but they are able to perform a huge amount of trades without paying any transaction fees to the bitcoin network.