Updated 16 October 2026 · Edited by the Benchmark Buyer team · How we review
We do the homework you'd do before buying, so you don't have to. Like any careful buyer, we read the independent security audits, the expert reviews and what users say, then sum up where they agree and where they don't. We don't run our own tests. This guide draws on the encryption and certification facts each provider documents, 1 independent security audit from the last 18 months, and 7 expert reviews published between April and October 2026. It covers cloud storage where you can keep your files private with end-to-end encryption, meaning only you hold the keys.
The short answer
Sync.com is the clearest consensus pick. It encrypts every account end to end by default, and five of our seven expert sources list it, two of them first. Internxt and Proton Drive are close behind; Internxt is the only provider here with an independent security audit from the last 18 months. All three have a free plan.
Stars show the consensus score out of 10, turned into a 5-star scale and rounded to the nearest half star; the exact score is in each product's section. Security evidence sums up whether files are end-to-end encrypted, any independent security audit from the last 18 months, and the security certifications each provider states. Popularity (●●●● very high to ●○○○ lower) is based on how many people have rated each provider's app on Google Play: very high (5m+ ratings), high (1m+), medium (500k+) or lower. It shows how widely used a product is, not how good it is, so it doesn't affect the score.
1. Sync.com: private by default, and the experts' favourite
★★★★½Consensus score: 9.2
Sync.com appears in five of our seven expert lists. Cloudwards and eSecurity Planet rank it first, TechRadar third (best for syncing), and Tom's Guide and Gizmodo fourth; Tom's Guide names it best for security. Every account, free or paid, is end-to-end encrypted, and Sync.com says it is SOC 2 certified. We found no published independent audit of its encryption.
"If you want to keep your files as secure as possible, then Sync is a great option." (Tom's Guide)
"All accounts with Sync.com enjoy zero-knowledge encryption, whether your account is free or paid." (Cloudwards)
Worth knowing: in 2024, researchers at ETH Zurich showed that a compromised Sync.com server could swap encryption keys or tamper with shared files, and said Sync.com had not responded to them by October 2024 (ETH Zurich research). This research is older than 18 months, so it doesn't affect the score.
Who it suits: anyone who wants everything encrypted without changing any settings, including on a free account.
What users say: people like its security and privacy, ease of use, sharing links and shared folders, value, reliable syncing and access across devices. The most common complaints are syncing problems or lost files, slow customer support, and billing and subscription costs. (Capterra)
2. Internxt: the only one with a recent independent audit
★★★★½Consensus score: 8.7
Internxt is the only provider here with an independent security audit from the last 18 months. Securitum, a European security testing firm, checked its web, desktop and mobile apps and its servers, and in August 2025 Internxt reported that "no severe vulnerabilities were found" (Internxt). Every account, including free ones, is end-to-end encrypted. Gizmodo ranks it second (best for sensitive documents), TechRadar and Cloudwards fourth, and eSecurity Planet sixth.
"Internxt has a clean interface and first-rate security credentials." (TechRadar)
"The keys stay with you, so Internxt can't read your documents, even on a free account." (Gizmodo)
Who it suits: people storing sensitive documents who want proof from an outside auditor, not just the provider's word.
Proton Drive is one of only three cloud services recommended by Privacy Guides, a non-profit privacy site. Cloudwards ranks it third, and Zapier names it best for a complete privacy ecosystem. Files are end-to-end encrypted by default, Proton says file names and folders are encrypted too, and Proton states it is ISO 27001 certified. Securitum audited Proton Drive's web app in 2021 and its mobile apps in 2022, but those audits are older than 18 months, so they don't count towards the score.
"Proton works on all devices and takes the complicated parts out of maintaining your digital privacy." (Zapier)
Where opinions differ: TechRadar, Tom's Guide, Gizmodo and eSecurity Planet leave it out of their lists, so it is listed by fewer experts than the two above.
Who it suits: people who already use, or want, Proton's encrypted email, VPN and password manager alongside their storage.
4. NordLocker: an encrypted locker for sensitive files
★★★★☆Consensus score: 8.3
Gizmodo ranks NordLocker third, eSecurity Planet fifth and TechRadar seventh (best for ease of use). Files you put in a locker are end-to-end encrypted. We found no independent audit of NordLocker for home users and no current certification, so its security evidence rests on its encryption design alone.
"With its zero-knowledge encryption system, not even a NordLocker security worker can decrypt your stored files." (TechRadar)
Who it suits: people who want to lock away specific sensitive files rather than sync everything.
5. pCloud: widely recommended, but encryption costs extra
★★★★☆Consensus score: 7.6
pCloud is as widely listed as Sync.com: Gizmodo ranks it first, TechRadar and Cloudwards second, eSecurity Planet fourth and Zapier eighth. pCloud lets you choose to keep your files in the EU (Luxembourg) or the US, and states that it is ISO 27001 certified. But end-to-end encryption is only available through pCloud Crypto, a paid add-on, which is why it scores lower than the providers above.
"pCloud offers excellent security and privacy, and has one of the best free cloud storage plans available." (Cloudwards)
"Standard encryption leaves the keys with pCloud." (Gizmodo)
Worth knowing: the same 2024 ETH Zurich research found weaknesses in pCloud's encryption that a compromised server could exploit, and said pCloud had not responded by October 2024 (ETH Zurich research). This is older than 18 months, so it doesn't affect the score.
Who it suits: people storing large photo, music and video libraries, who are happy to pay extra to encrypt their most private folders.
6. IDrive: a top all-rounder, with encryption as an option
★★★½☆Consensus score: 7.4
IDrive is TechRadar's and Tom's Guide's top pick for cloud storage in general, and second at eSecurity Planet. It states it holds SOC 2 Type 2 certification. End-to-end encryption, using a private key only you know, is an option rather than the default, which lowers its security score here.
"IDrive is a terrific cloud storage solution - a fantastic all-rounder with an easy-to-use backup option." (TechRadar)
Where opinions differ: IDrive tops two general cloud storage lists, but none of the security-focused lists from Gizmodo, Cloudwards or Privacy Guides includes it.
Who it suits: people who want backup of their computers and phones plus file storage in one account. Choose the private key option at setup if privacy matters to you.
What about Google Drive, OneDrive, Dropbox and iCloud?
The big names are the most popular choices, and Google Drive and OneDrive appear in three and four of our expert lists. But none of our sources reports end-to-end encryption for UK home users on these services, so we haven't ranked them in a guide about secure storage. Google Drive "doesn't have end-to-end encryption" (TechRadar), and Tom's Guide notes that Google holds the encryption keys. Tom's Guide lists the lack of zero-knowledge encryption as a drawback for OneDrive, and says Dropbox encrypts files in transit and at rest. Apple's optional end-to-end encryption for iCloud, Advanced Data Protection, has been unavailable to new UK users since 21 February 2025, after a UK government order (TechRadar).
Not ranked, and why
MEGA encrypts files end to end by default, and Tom's Guide names it best for privacy, but only two of our seven expert sources list it. We need at least three.
Tresorit is recommended by Privacy Guides and ranked fifth by Cloudwards, but only those two expert sources list it. Its published audits and certification date from 2019 to 2022, older than our 18-month limit.
Icedrive appears in only one expert list. The 2024 ETH Zurich research found weaknesses in its encryption and said Icedrive "opted not to address the issues" (ETH Zurich research).
Backblaze, Box, Jottacloud and Peergos each appear in only one expert list.
How we score
We don't run our own tests. There are no regular independent lab tests for cloud storage, so each product's consensus score combines three things:
Security evidence (40%): a score out of 100 built from what we can document:
End-to-end encryption (half of this score): on by default scores full marks; optional or a paid add-on scores half.
An independent security audit published in the last 18 months (30%).
A current security certification the provider states, such as ISO 27001 or SOC 2 (20%).
Where we couldn't find an audit or certification, we leave that part out and score on the rest, rather than marking the provider down for it.
Expert rankings (40%): each product's position in 7 expert lists, from TechRadar, Tom's Guide, Cloudwards, Privacy Guides, Zapier, Gizmodo and eSecurity Planet.
Breadth of agreement (20%): how many of those 7 lists include the product.
To be ranked, a product must offer end-to-end encryption to UK home users and appear in at least three expert lists. No product can score above 9.9. We leave out evidence older than 18 months; for example, Tech Advisor's cloud storage guide was last updated in January 2024, so it isn't counted, and older audits and research are mentioned only as background. Affiliate commission plays no part in the score.
Evidence last checked: 16 October 2026. Full details on how we review.