MEGA is a cloud storage service launched in New Zealand in 2013 that encrypts files on your device before they are uploaded. Since 2025 its cloud service has been run by a company registered in Hungary. Plans for individuals range from a free plan with 20 GB to Pro III with 20 TB, and every paid plan includes MEGA’s VPN and password manager.

MEGA calls its service zero-knowledge: it says it cannot read your files. In 2022 cryptographers at ETH Zurich showed that an attacker in control of MEGA’s servers could recover a user’s keys, and MEGA says its 2023 update closes these attacks. No security audit of MEGA has been published.

Encryption & Key Custody

MEGA says every file is encrypted on your device with its own random key, and that those keys are encrypted with a master key that only your password can unlock. This puts key custody with you: MEGA stores data it says it cannot decrypt. Your password is not sent to MEGA; the apps turn it into keys with PBKDF2, a key derivation function that MEGA’s own whitepaper calls “not the latest, best or state of the art”, so a long, unique password matters.

The metadata encryption covers file names, folder names and thumbnails. It does not cover file sizes, the order of file versions or which file sits in which folder: MEGA’s privacy policy lists these among the data it keeps unencrypted, and its whitepaper says MEGA chose not to protect the folder structure cryptographically, so that it can move or remove files itself.

Sharing works in two ways. A link carries the file’s key after the # sign, a part of the address that browsers do not send to MEGA, so the recipient can decrypt the file without an account. You can send the key separately from the link, and on paid plans add a password and an expiry date. A shared folder gives another MEGA user its key, encrypted with that user’s public key. Checking that the public key really belongs to that person, called contact verification, is optional: since March 2023 MEGA shows a warning for folders from people you have not verified, but still accepts them. If you share a folder with someone you have not verified, a compromised MEGA server could hand you a different key and read the folders you share with that person afterwards.

Account recovery depends on a recovery key, which you can export only while signed in. If you forget your password and are not signed in anywhere, the recovery key lets you set a new one. Without it, MEGA can only reset the account, and the files in it become unreadable; if the password or key turns up within 60 days, support can bring the old account back. Export the recovery key when you open the account and keep it apart from your password.

The browser version decrypts files inside the browser with code it loads from MEGA’s servers on every visit. MEGA checks the files of that code against a list of fingerprints, but the list also comes from MEGA, so in the browser you rely on MEGA serving unaltered code. MEGA’s extension for Chrome and Edge keeps the code on your computer instead; the desktop and mobile apps do not load it on each visit either.

Trust & Transparency

MEGA publishes the source code of all its cloud storage apps, including the web version, on GitHub. Most of it is under MEGA’s own licence, which allows reading and testing the code for flaws but is not an open-source licence; the software library the apps are built on is under a standard open-source licence. The server code is not published. No security audit of MEGA’s encryption or apps has been published. MEGA pays up to €10,000 for each vulnerability reported to it.

Research into MEGA’s encryption

The most detailed outside review of MEGA comes from academic cryptographers, not from an audit. In 2022 Matilda Backendal, Miro Haller and Kenneth Paterson of ETH Zurich described five attacks open to anyone controlling MEGA’s servers. The main one recovered a user’s private key after 512 logins with a password; with it, the attacker could decrypt the user’s files and plant files that the apps would treat as uploaded by the user. Researchers at UC San Diego cut the number of logins to six. The root cause, the ETH team wrote, is that one master key protects all other keys in a mode without any check that the stored keys have not been altered.

MEGA updated its apps in June 2022 with extra checks on the private key and said it knew of no account compromised this way. The ETH team noted that this fix differed from the changes they proposed. In 2023 a team from Royal Holloway and ETH Zurich showed that the new checks could themselves be used to recover the private key, with hundreds to thousands of logins. MEGA released a wider update in March 2023 that, MEGA says, makes its apps immune to the private-key recovery described in all three papers, and to substituted public keys for contacts you have verified. MEGA’s whitepaper is dated June 2022 and does not describe that update, and MEGA’s announcement does not say whether stored keys are now protected against alteration.

The 2018 Chrome extension incident

On 4 September 2018 an attacker uploaded a malicious version of MEGA’s Chrome extension to the Chrome Web Store. It asked for permission to read and change data on all websites and, if granted, sent logins typed into Amazon, Microsoft, GitHub and Google, keys from cryptocurrency wallet sites, and data from login forms on any other site to a server in Ukraine. The researcher who found it put the number of affected users at over 1.6 million, which is the number of people who had the extension installed, not a count of confirmed thefts. MEGA said it uploaded a clean version four hours later and that the Firefox add-on and the desktop app were not affected. This security incident exposed passwords for other websites, not the files stored in MEGA.

MEGA says the updates of its browser extension are cryptographically protected. Its whitepaper says that for the Chrome extension this protection is Google’s signature, added when an update is uploaded to the Chrome Web Store, and that the store account uses a strong password and two-factor authentication.

Jurisdiction and what MEGA sees

Since May 2025 the contract for MEGA’s cloud service has been with MEGA Privacy Kft, a company registered in Hungary, under Hungarian law; before that the operator was in New Zealand. MEGA says personal data is stored in Japan, Canada and the EU and none in the United States. Its website does not name the company’s shareholders.

Whatever the encryption, MEGA keeps your email address, payment records, IP addresses with the time of each login, upload and link, your device type, the file details described above, and the email addresses of your contacts. The privacy policy allows MEGA to give authorities your files, in encrypted form, and your account data. Analytics and advertising cookies are used only if you accept them, which makes the telemetry opt-in, but the account metadata above is kept either way. MEGA publishes a yearly transparency report on takedowns and requests from authorities.

Features & Sync

The desktop sync app runs on Windows, macOS and Linux. It syncs the whole cloud drive or chosen folders, backs up folders from your computer, and can stream audio and video. The mobile apps upload camera photos automatically, keep files available offline and scan documents. MEGA sets no limit on file size, but downloads of large files in the browser can run into the browser’s own limits.

File versioning keeps up to 100 versions of each file, with no time limit, and any version can be restored. Rewind restores files and folders deleted from a folder back to a chosen date: 30 days back on the free plan, where restored files can be viewed only, and up to 60 days on paid plans. MEGA has no collaborative editing of documents.

Downloads are counted against a transfer quota. Free users and people without an account who download from your links are limited by how much has been sent to their IP address in the past six hours; paid plans come with a fixed amount, such as 3 TB a month on monthly Pro I. A file starts to count only after it has been downloaded in full more than 10 times, so the limit matters mostly for links shared widely.

Usability & Platforms

There are apps for Windows, macOS, Linux, Android and iPhone, and the browser version works in current Chrome, Firefox, Edge, Opera and Safari. Two-factor authentication uses a six-digit code from an authenticator app; MEGA does not send codes by text message. A lost authenticator is replaced with the recovery key, so that key is needed for two kinds of lockout.

Price & Value

The free plan gives 20 GB and a limited download allowance. MEGA may delete the files of a free account after at least 10 months without a sign-in, following warning emails.

Paid plans, billed yearly: Essential costs €40 a year for 200 GB, Pro Lite €59.99 for 750 GB, Pro I €99.99 for 3 TB, Pro II €199.99 for 10 TB and Pro III €299.99 for 20 TB. Monthly billing costs €4.99 for 750 GB, €9.99 for 3 TB, €19.99 for 10 TB and €29.99 for 20 TB; Essential is sold only yearly. Yearly plans give twelve times the monthly download allowance. Prices are charged in euros.

MEGA does not offer a money-back guarantee. Residents of the EU can cancel a purchase within 14 days, and residents of Brazil and South Korea within 7 days. Elsewhere a payment is refunded only if it was charged in error and reported within 30 days, or if it was made by mistake and the plan was not used, within 24 hours.

Pros and Cons

MEGA says files, file names and folder names are encrypted on your device and it never holds the keys
Links carry their key in a part of the address the server never receives, and the key can be sent separately
Up to 100 versions of each file and Rewind to restore deleted files
No file size limit, and desktop sync on Windows, macOS and Linux
20 GB free, and 3 TB for €99.99 a year

MEGA has not said whether the keys stored under your master key are now protected against alteration, the root cause of the key-recovery attacks published in 2022 and 2023
Checking a contact's key before sharing a folder is optional, so a compromised server could swap the key of an unverified contact
File sizes and folder structure are readable to MEGA
No published security audit, the server is closed, and app source code is licensed for review only
Losing both the password and the recovery key means losing the files
The browser version loads its encryption code from MEGA on every visit unless you use the Chrome or Edge extension
No refunds outside the EU, Brazil and South Korea except for billing errors
Downloads by free users and people opening your links are limited by a transfer quota
No collaborative editing of documents

Our Rating

Encryption & Key Custody6.5/10
MEGA says files, file names and folder names are encrypted on your device and it never holds the keys. MEGA says its 2023 update closes the key-recovery attacks published by independent cryptographers, but it has not said whether the keys stored under your master key are now protected against alteration, the root cause the researchers named. The folder structure is not cryptographically protected, checking a contact's key before sharing a folder is optional, and losing both the password and the recovery key means losing the files.
Trust & Transparency4.5/10
MEGA publishes the source code of its cloud storage apps under a licence that allows review only, keeps the server closed and has no published security audit. It does not name its owners, and in 2018 an attacker published a malicious version of its Chrome extension that stole passwords for other websites. MEGA publishes a yearly transparency report and pays up to €10,000 for reported vulnerabilities.
Features & Sync7.5/10
Desktop sync and backup on Windows, macOS and Linux, no file size limit, up to 100 versions of each file, and Rewind to restore deleted files to a past date. Downloads count against a transfer quota, which for free users and people opening your links is set per IP address and can pause a download, and there is no collaborative editing.
Usability & Platforms7.5/10
Apps for Windows, macOS, Linux, Android and iPhone and a browser version, with two-factor authentication through an authenticator app. Downloads of large files in the browser work best in Chromium-based browsers or through the desktop app.
Price & Value8.5/10
Pro I costs €99.99 a year for 3 TB and Pro III €299.99 a year for 20 TB, and the free plan holds 20 GB. Outside the EU, Brazil and South Korea a payment is refunded only if it was charged in error.

Overall6.6/10

Encryption & Key Custody 30% · Trust & Transparency 25% · Features & Sync 20% · Usability & Platforms 15% · Price & Value 10%

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