How can I export all passwords from a vault without installing an App on Windows or Mac?

@hwmrocker: Thanks for reaching out! Unfortunately plaintext export only works in 1Password for Mac and 1Password for Windows, and direct OPVault export with those and 1Password for Android (though not quite an export, 1Password for iOS can sync to an OPVault in Dropbox). You could, however, use the Windows app in a VM only Linux if you don't have direct access to any other computers/OSes.