Encryption on your computer, for the cloud you already use
Your cloud stores your files. It doesn’t need to read them.
CryptoUpload locks every file on your computer before it leaves. Google Drive, Dropbox, OneDrive or your own server receive nothing but unreadable blocks. Only you hold the key.
- Free and open source
- No account to create
- No server of ours in between
- Zero telemetry
I
Before it leaves
Every file is split into blocks and every block is sealed with AES-256-GCM, here, on your computer. Even its name disappears. Nothing readable leaves this machine.
Each block is sealed on its own. The name changing above is an illustration.
II
On the way
Only sealed blocks set off. Destination: the storage you already have, and may already pay for. No need to switch clouds, or to trust a new one.
Point at or tap a destination to see how it connects.
III
On the other side
This is your cloud as the people who run it see it. Move the light over the list: inside the circle is what you see, outside is what is left for them.
This is your cloud as the people who run it see it. Drag the light over the list: inside the circle is what you see, outside is what is left for them.
What you see
- Rental contract.pdf1.8 MB14 Sep 2026, 09:12
- Holiday photo 0412.jpg4.1 MB12 Sep 2026, 18:40
- Passwords.kdbx46 KB11 Sep 2026, 22:05
- Tax return 2025.pdf920 KB08 Sep 2026, 10:31
- Medical results.pdf2.3 MB05 Sep 2026, 16:18
- Invoice 0043.pdf140 KB03 Sep 2026, 08:57
- Thesis final v3.docx1.2 MB29 Aug 2026, 23:44
- Wedding video.mp41.4 GB21 Aug 2026, 12:09
What the provider no longer sees
- File and folder names
- What is inside the files
- Which folder sits inside which
What the provider still sees
- How many files there are
- How big each one is
- When it was written
- The address you connect from
Illustrative example: the names on the provider’s side are made up, in the shape of real ones.
More than a lock
Protection that gets in the way gets switched off. This one stays out of it: the vault is a drive like any other, yesterday’s version can be brought back, and backups can be made immutable.
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A drive like any other
The vault shows up among your computer’s drives. Open, edit and save with the programs you always use, on Windows and Linux. The encryption works underneath.
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A huge video, no waiting
Open a large file that lives in the cloud without downloading all of it first.
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A folder that is always protected
Pick a folder and every change is encrypted and uploaded. You decide the hours, the bandwidth limit and what to leave out. If the connection drops, the upload resumes where it stopped.
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Go back to yesterday
Saved over something by mistake? Version history gives you the earlier copy back.
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Nothing vanishes silently
Two devices change the same file? Both versions are kept. Better one extra file than lost work.
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A copy that stolen credentials cannot erase
With S3 Object Lock, uploaded copies cannot be permanently erased until the retention period you set runs out, even with your storage credentials. A sync that looks like an attack is paused for your confirmation: a heuristic, not a guarantee.
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A real key, in your pocket
Unlock with a FIDO2 security key. Or demand both: password and key.
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A plan B that works
The 24 recovery words open the vault even if you forget the password. And you can print an emergency recovery kit to put away.
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Share without a middleman
Several people on the same vault, with no account server in between.
Who it is for
For those who keep their life in a folder
Documents, photos, tax returns, medical results. You keep them in the cloud because it is convenient: they stay convenient, but only you can read them.
For those who look after other people’s data
Clients, patients, case files. If your provider suffers a breach, what leaks from its side is unreadable blocks, not their documents. An extra layer, not the only one.
For those who run their own server
S3-compatible storage, SFTP or WebDAV on your own server, immutable backups with Object Lock, and the command line to automate it all.
Download
Take back the keys.
Free, no account. Install it, choose a password, and the files you put in the vault reach the cloud already encrypted. Change your mind? Copy them out and uninstall: no strings.
Start with a folder of copies. Leave the originals where they are until you have seen everything open again, with the 24 words too.
For now CryptoUpload runs on Windows and Linux. Send yourself the link and download it from your computer.
For now CryptoUpload runs on Windows and Linux. A macOS version is planned, but not available yet.
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Your system
Windows
.exe installer
Available with the first public release.
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Your system
Linux
.deb for Debian and Ubuntu, AppImage for every other distribution
Available with the first public release.
What it does not protect Getting started guide
Up and running in three steps
Install
An ordinary installer. No sign-up.
Create your vault
Choose a password and put the 24 recovery words somewhere safe.
Connect your cloud
Choose where to keep it and what to protect. From there it runs by itself.
For those who want to look inside
Up to here, the short version. From here on: the numbers, the extra protections and the limits, stated plainly.
IV
Don’t take our word for it. Try it.
Type anything. Your browser encrypts it right now with AES-256-GCM, the same cipher the app uses. The key is random, lives only in this page and is never sent anywhere.
What a provider would store
- Nonce
- Encrypted data
- Authenticity seal
Tiny blocks, so you can see them: 8 bytes each, one row apiece. The app uses 32 KiB blocks, encrypts names too and uses the UVF format. The app also binds each block to its file and detects a cut by its end-of-file rule: this is the idea, not the format.
This demo needs a browser with Web Crypto, on a secure (https) page, with JavaScript enabled.
The lock, in numbers
No home-made algorithms: public, standard ones, and an open format, UVF. Our additions (anti-rollback record, sharing, private profile) are written down in the public specification. The code is public, under the GPLv3: anyone can read it and check it.
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256 bit
A key for every file
AES-256-GCM, with a different random key for each file. Everything is encrypted on your computer.
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32 KiB
A seal on every block
Change a single bit and the file will not open. A file cut short is rejected, not shown shorter.
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256 MiB
The price of every guess
Anyone guessing your password pays 256 MiB of memory for each attempt (Argon2id).
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24 words
Your way back in
A recovery phrase shown once and never stored. Change your password without re-encrypting your files.
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7 destinations
You choose the storage
Google Drive, Dropbox, OneDrive, S3-compatible storage, SFTP, WebDAV or a local disk. More than one, if you like.
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0 servers of ours
Nobody in between
No account, no subscription, no telemetry. The app talks only to the cloud you chose and, unless you turn it off, checks whether a new version is out.
Extra protections, off until you turn them on
The basic protection is always there. These are extras: off until you turn them on, each one stating what it protects and what it costs. Turning them on is free; turning them off asks for the password.
It locks itself
The computer goes to sleep, a remote desktop session starts, you stay idle: the vault locks and the drive unmounts, without waiting for you.
The limit: A program already running as your user while the vault is open cannot be stopped completely.
A trap for whoever snoops
The drive holds fake files that no honest program opens. If something reads them, or opens a great many files in a few seconds, the vault locks at once and tells you which program it was.
The limit: On Linux today. A virus written specifically for CryptoUpload can recognise the decoys.
Disguised sizes
With the private profile every file is rounded up to a standard size, about 12 % more at most: files of similar weight become identical to anyone watching the server. Name lengths also fall into five bands.
The limit: Chosen when you create the vault and not changed afterwards. It takes a little more space.
Scrambled timing
Files leave in random order, and each automatic run waits a random time, up to 24 hours: arrival times no longer mirror when you edited. Through a proxy the provider does not see your address.
The limit: Volume and frequency stay visible over time. Browser sign-in for Google Drive, Dropbox and OneDrive bypasses the proxy; S3 works only through an HTTP proxy.
Two keys, not one
Password and FIDO2 security key together: the password alone does not open it, and neither does the key. A password someone spied on is no longer enough.
The limit: The 24 words still open it on their own, as the emergency exit: keep them safe.
The way back in, split up
The 24 words become, for example, five shares of which three are enough. A stolen share reveals nothing; a lost share does not lock you out.
The limit: It only protects if you destroy the copies of the whole phrase.
One key to close everything
A button or a keyboard shortcut: vault locked, drive unmounted, list of recent vaults and activity log erased, keys removed from the system keychain.
The limit: It does not touch the data on the server or your original files.
And more: read-only drive, programs allowed to read the drive (on Linux), fewer traces on disk, a notice of failed attempts to open the vault.
V
What a lock cannot do
Better to know before you trust it with anything. These are today’s limits.
- CryptoUpload has not yet had an independent security audit. It has had an internal review only.
- Your provider still sees how many files you have, how big they are, when they were written and where you connect from.
- A computer that is already compromised, or a vault left unlocked on a machine someone else uses, is outside what it can protect.
- Changing a password or removing a person from a shared vault does not undo what they have already seen.
- A provider can refuse to give your files back. The lock detects tampering; it cannot force a provider to cooperate. That is why you can keep the vault on more than one destination.
- Lose both the password and the 24 words and nobody can recover your data. Not even us. That is why there is a recovery kit to print and put away.
Why I do this (spoiler: not for the money)
My personal data has ended up in more than one breach, at companies I had trusted with it. Whoever got in walked away with a fat bundle of information about me, all in plain text, without a scrap of encryption: readable by anyone, for any purpose.
CryptoUpload starts there. I cannot take that data back, but I can make sure the next files, mine and yours, reach the cloud already unreadable.
I earn nothing from this program: I do not sell it, I put no ads in it, I have no subscription to offer you, and I could not sell your data even if I wanted to, because I cannot see it. The only thing I accept is voluntary donations. I do it for the love of data protection and, I admit, for a pinch of payback.
If you work in security, you can help with more than a donation: read the code, hunt for bugs, propose changes. One rule only: security problems are reported privately to security@cryptoupload.org, never in public.
The person who writes CryptoUpload
CryptoUpload: the accounts
- Sales of the program
- €0.00
- Subscriptions
- €0.00
- Advertising
- €0.00
- Sales of your data
- impossible
- Voluntary donations
- if you like
- Time worked
- over a year
- Expenses (all mine)
- plenty
- Total earned
- €0.00
Thank you and goodbye. Hold on to your data.
Questions, short answers
Do I have to switch clouds?
No. CryptoUpload works on top of the storage you already have: Google Drive, Dropbox, OneDrive, S3-compatible storage, SFTP, WebDAV or a plain disk.
Do I need to create an account?
No. There is no CryptoUpload account and no server of ours between you and your files. You use the cloud sign-in you already have.
Can you read my files?
No. Files are encrypted on your computer and we receive nothing. The keys unlock only with your password, your 24 words, or an unlock method you add yourself.
What if I forget my password?
You use the 24-word recovery phrase shown to you when you create the vault. Lose both the password and the phrase and nobody can recover the data: that is the price of a key only you hold.
What if one day I want to stop?
You leave whenever you like. Open the vault, copy your files out as they are, and uninstall. There is nothing to cancel, and the vault format is openly documented, not a cage.
Does it cost anything?
No. It is free software, and free of charge. Your cloud provider may charge for storage, as it does today. No catch: no ads, no data to sell (we never see it). The reason is under “Why I do this”.
Can I use it at work?
Yes. The licence allows it and it costs nothing. There is no support contract and no guaranteed response time, though: one person writes it. Use it as an extra layer on top of a provider that already meets your obligations, not instead of your other measures.
Does it send data about me anywhere?
No telemetry. The app contacts your cloud provider and, unless you turn it off in Settings, checks for updates.
Has it been audited?
Not independently yet. It has had an internal security review, the code is public, and the aim is to pay for an outside audit with grants. What that means for you, and what we suggest in the meantime, is on the Security page.
Was it written with AI?
Yes. CryptoUpload has a single developer, who used an AI assistant to help write the code and to find and verify bugs: working alone, a second, objective opinion was needed. The decisions remain one person’s, the cryptography is that of public algorithms, and the code is open so that anyone can check it.
What about Mac and phones?
macOS, Android and iOS are planned, but not available yet.
What if the project stops?
The installed program keeps working: it depends on no server of ours. You can open your files and copy them out whenever you like. Format and code are public: anyone can carry it on.
Product names belong to their owners. CryptoUpload is not affiliated with or endorsed by any of them.
CryptoUpload
- Encryption
- AES-256-GCM, on your computer
- Vault format
- UVF, an open format
- Licence
- GNU GPLv3, with an App Store exception
- Price
- Free
- Telemetry
- None
- Source code
- Public, under the GPLv3
- Questions and press
- info@cryptoupload.org
- Security reports
- security@cryptoupload.org