The best secure file transfer services
"Secure file transfer" describes at least four different promises, and most services keep only some of them. Before comparing anything, work out which of the four you actually need — because a service that is excellent at one can be useless at another, and the marketing word is identical in every case.
The four promises
1. Encrypted in transit. Nobody can read the file while it is moving over the network. This is HTTPS. Every service in this category does it, it is table stakes, and any provider advertising it as a feature is padding.
2. Encrypted at rest. The file is encrypted while stored. Almost universal too — but the question that matters is who holds the key, and that is rarely on the marketing page.
3. End-to-end encrypted. The service never holds the key. It cannot read your file even if compelled to. This is a much stronger promise, and much rarer than the number of companies claiming it. What it really means, and how to check.
4. Access control. Who can reach the file, for how long, how many times, and can you revoke it. This is the one that actually prevents most real-world incidents, and it is the least discussed.
Most people asking for "secure file transfer" want the fourth and assume they are asking for the third.
Which one you need
Sending a contract to a client. You want access control. Expiry, a password if the email might be forwarded, and the ability to revoke. End-to-end encryption is not the risk here; the risk is the link sitting in an inbox for three years.
Sending health, legal, or special-category personal data. You want access control plus a data processing agreement plus jurisdiction clarity. Sending sensitive client data covers the obligations that come with it.
Sending something where the service itself is part of your threat model. Now you want genuine end-to-end encryption, and you should be sceptical, because the claim is cheap to make.
Sending a video to a colleague. You want none of this. Use whatever is convenient.
How to check the claim rather than believe it
Three questions separate real end-to-end encryption from the marketing version:
Can the service show a preview or thumbnail of my file? If yes, it decrypted it, so it holds the key. This is the fastest test there is, and it is decisive.
Can they scan for viruses? Same logic.
If I lose my password, can they recover my files? If yes, they hold the key. Real end-to-end encryption means losing the key means losing the file — that is the cost of the property, and any provider offering both recovery and end-to-end encryption is claiming something that does not fit together.
That last one is the honest test, and it is worth applying to anything sold as zero-knowledge.
Where services stand
All from each company's own documentation on the date stated. No competitor prices appear here.
Most mainstream transfer services — WeTransfer (checked 31 July 2026), Dropbox Transfer (31 July 2026), Filemail (1 August 2026), Smash (1 August 2026), SwissTransfer (1 August 2026) — are in the "encrypted in transit and at rest, with the provider holding keys" category. That is a reasonable, normal design. It is what makes previews and virus scanning possible, and for most work it is the right trade.
Where they differ is access control, and that is worth comparing directly: password protection, expiry you can set, download limits, and whether you can revoke a link after sending. Ask about revocation specifically — it is the control people most often assume exists.
Yungle, which I build: every file is encrypted at rest with its own key, and the key is held by the service. I say "always encrypted" rather than the stronger phrase because previews and virus scanning happen server-side, and those require decryption. There is also an opt-in mode where the browser seals the file before upload and the key never reaches the server — for the cases where the service should be part of your threat model. Access controls are passwords, expiry, download limits and link revocation. It runs on one server in Germany, and there is a DPA to read.
Availability is a security property too, and on that axis a large provider beats a small one — worth weighing if a file being reachable on a deadline is part of what you mean by secure.
The controls that prevent actual incidents
In practice, leaks in this category happen for boring reasons, not cryptographic ones:
A link forwarded to the wrong person. Fixed by expiry and revocation, not by encryption.
A link that still works two years later. Fixed by retention you actually set. How long should you keep client files.
The wrong folder shared. Fixed by handing over a copy rather than lending access to your storage.
A password sent in the same email as the link. Fixed by sending it through a different channel, which costs nothing and is skipped constantly.
If you do those four things on an ordinary service, you are ahead of most people using a "secure" one badly. The step-by-step version is in how to send large files securely.
Choosing
Start by naming which of the four promises you need, then check that claim with the preview and password-recovery tests, then compare access controls, then compare jurisdiction if the data involves other people. Compare transfer size last — it is the number every page leads with and the one least likely to matter to a decision about security.