Which cloud storage services are free and secure?

What does "secure" mean to you - are you thinking about encryption, or more about your data not being used for advertising?

Basically, I'd say: completely free and actually secure is tricky. Nextcloud is open source and you can self-host it if you've got the technical skills - then you have full control. ProtonDrive encrypts your files end-to-end, but it has a small free version with limited storage. Sync.com and Tresorit are considered secure, but they cost money for usable amounts of storage. Google Drive and Dropbox are practical, but security isn't their strongest suit - Google uses your data partly for training AI models, which a lot of people don't want.

If you only need to save a few files now and then, the free version of Proton Pass might be enough. But honestly: if you really want security, you usually have to pay or set up a server yourself. Most people just go with Nextcloud on a cheap VM or trust a premium subscription from a reputable provider. It really depends on how paranoid you want to be and how much storage you need.

Try Nextcloud or Synology - you can self-host them, then you don't have to trust any third-party provider and you have maximum control over your data. The previous answers are right that "free and secure" don't go together easily, but self-hosting solves the problem differently than just picking a big provider. Of course, you'll need a server or an old laptop that you keep running - is that doable for you, or do you need something that just works right away?

Super simple: Google Drive and OneDrive give you 15 GB and 5 GB free respectively, and both encrypt your data in transit and at rest - that's plenty for most people. The trick a lot of folks miss: use one of the free providers mainly for non-critical stuff (photos, documents), and for really sensitive data (passwords, tax documents), encrypt it locally first with a tool like VeraCrypt before you upload it - then you don't have to worry about how the provider handles their servers.

It depends on whether you want to handle the infrastructure yourself or prefer something ready to use. With the big free providers (Google, Microsoft, Dropbox), you have to accept that your data sits on someone else's servers - encryption is there, but you don't control who has access. Self-hosted solutions like Nextcloud are safer in the sense that only you have control, but then you need your own server and have to handle updates and backups yourself, or it gets insecure pretty fast.

What a lot of people miss: free + secure + reliable - that's an unrealistic triangle. You either pay with your data (big providers), or with your time and technical know-how (self-hosting), or with money (paid services). For regular users, I'd lean more toward Proton Drive - you get it free with 1 GB and they have end-to-end encryption built in, so they don't make money off your data.

I use multiple services in parallel myself, because no single solution really covers everything. Sensitive stuff tends to end up on local hard drives for me, but I still need something in the cloud for everyday things.

The thing is: "free" and "secure" go together like oil and water. The free offerings from Google, Microsoft and co. do encrypt your data in transit and in storage, but your account itself is the price - your usage data flows into their systems. If that doesn't bother you and you're already signed up with them anyway, 15 GB on Google Drive or 5 GB on OneDrive are totally usable. The biggest security advantage: they have massive resources for security infrastructure.

If you want real control, you need either money or a self-hosting solution like Nextcloud. But that costs you time setting it up, and then the security depends on your setup - not automatically better, just distributed differently. For "free and secure" without major compromises, there's really nothing. Better to decide which compromise works for you.