Chipmixer starts a 48 hour session when entering their system. ChipMixer requires no registration and makes mixing your bitcoins very easy using a casino like system, which is off the blockchain. You have 48 hours to mix your coins after starting a session before all logs are automatically erased. You can extend this at anytime if for some reason your transactions do not confirm if you sent with a low fee.
ChipMixer also makes mixing your bitcoin more exciting by allowing you to gamble the chips and break them into different denominations. You can also give a tip to the mixing service since it currently takes no fees besides the bitcoin network standard rates at the given time.
When withdrawing, you get the private key of each “chip”, having a standard size. Because they standardize the outputs, they can generate outputs before receiving your inputs. This way there simply cannot be any taint. Since they provide you with the private keys, it’s up to you to chose your own time delay and miner’s fee.
For users that are not familiar with private keys, ChipMixer also provide a withdraw-button for easy withdrawings similar to the Bitcoin Blender and Helix Grams. But in this case you have no control over the fees AND the withdrawal has to happen within 48 hours unless you extend your session.