TLDR: The answer? 7 days! If that's too short, sign up to our paid service, WeTransfer Pro, and take more control of your transfers.
When uploaded with the free service
When sending transfers through the free service (at https://wetransfer.com) they are available for 7 days. After which they expire and are removed from our servers. We don't keep a hidden stash of transfers so once they are deleted, it is no longer possible to download them.
In the case you're using the free service, please make sure you save your transfers to your hard disk, because once we've removed a file, there's no going back!
When uploaded by visiting a WeTransfer Pro Profile
Files sent through a someone else's WeTransfer Pro Profile (not your own), are available for four weeks instead of seven days, and will be saved in the Pro account's transfer overview. This is just one of the many features of Pro - you can learn more what else Pro can do right here.
The same rules apply as above: once the transfer expires, it really is gone forever.
When uploaded through a WeTransfer Pro account
Our Pro accounts can save up to 1TB of transfers they have sent permanently in their online Pro storage until they decide to delete them, or the account expires (which the files will be deleted after 28 days of account expiry). The default expiry period for transfers uploaded via WeTransfer Pro is 4 weeks, but this can be changed easily to ensure your files stay online for however long you like!
Don't have Pro yet? You're missing out! Just sign up here.