File Encryption
Lock any file with a password using real AES-256 encryption — in your browser.
Also known as: File locker, Password-protect a file, AES file encryptor
How it works
- 1Choose Encrypt to lock a file, or Decrypt to unlock a file this tool previously encrypted.
- 2Select or drag in your file.
- 3Enter a password (and confirm it, when encrypting) — a strength meter warns you if it's weak.
- 4Click Encrypt or Decrypt File and download the result.
Why use File Encryption
Real authenticated encryption
AES-256-GCM, not a toy cipher — the same encryption standard used across modern security-critical software.
Strong key derivation
600,000 rounds of PBKDF2, matching current OWASP guidance, instead of using your password directly as a weak key.
Fresh salt and IV every time
Encrypting the same file with the same password twice produces two unrelated results — key material is never reused.
Tamper detection built in
GCM's authentication tag means a wrong password and a corrupted file are both honestly reported, never silently decrypted into garbage.
Restores your original filename
The original name and file type are stored securely inside the encrypted content and restored automatically on decrypt.
Nothing transmitted, ever
Your file and your password are processed entirely on your device — neither is ever sent anywhere.
Who uses File Encryption
Protecting a sensitive document before cloud backup
Encrypt a file locally before uploading it to cloud storage you don't fully trust with the plaintext.
Sharing a confidential file over email
Encrypt an attachment and share the password through a separate channel, so email interception alone isn't enough to read it.
Archiving sensitive personal records
Encrypt scanned IDs, financial documents, or medical records before storing them long-term.
Protecting a USB drive's contents
Encrypt individual sensitive files before copying them to portable, easily-lost storage.
Securing a file before a temporary transfer
Encrypt a file before sending it through a file-sharing service, so the service itself never sees the contents.
Locking down draft or unpublished work
Encrypt an unreleased document or design file so only someone with the password can open it.
About File Encryption
Plenty of "file encryption" tools online are little more than a simple XOR cipher or a weak, home-grown scheme dressed up with a lock icon. This tool uses AES-256-GCM — a real, authenticated encryption standard used throughout modern security-critical software — with the encryption key derived from your password using PBKDF2 at 600,000 iterations, in line with current OWASP guidance for password-based key derivation. Weak or fast key derivation is one of the most common ways "secure" tools quietly undermine themselves; this one doesn't cut that corner.
A fresh random salt and initialization vector are generated for every single file you encrypt, even if you reuse the same password — so encrypting the same file twice with the same password produces two completely different, unrelated results. That matters because reusing key material is one of the classic mistakes that breaks otherwise-sound encryption.
AES-GCM is authenticated encryption, meaning it doesn't just hide your data — it can detect if the encrypted file was tampered with or corrupted. In practice, this means an incorrect password and a corrupted file produce the exact same honest "can't decrypt" result, rather than silently handing back garbled nonsense the way many simpler encryption schemes do.
Your original filename and file type are stored inside the encrypted content itself (not in the visible filename), so decrypting restores the exact original file — not a generically-named blob you have to rename and re-identify by hand.
File Encryption vs. other options
How Open Tools Library compares to desktop software and other online tools.
| Feature | Open Tools Library | Desktop software | Other online tools |
|---|---|---|---|
| Price | Free, unlimited | Often paid or subscription | Often free with daily limits |
| Installation | None | Required | None |
| File & password privacy | Never leaves your device | Stays local | Often uploaded to a server |
| Encryption standard | AES-256-GCM, authenticated | Varies by app | Often unclear or proprietary |
| Key derivation | PBKDF2, 600,000 rounds | Varies by app | Often none — password used directly |
| Tamper detection | Built in via GCM auth tag | Varies by app | Often absent |
Pro tips
- There's no password recovery by design — anyone (including us) who doesn't know the password cannot decrypt the file, which also means you can't either if you forget it.
- Use a genuinely strong, unique password for encryption — the strength meter is shown for a reason, since PBKDF2 can't make a weak password strong, only slower to guess.
- Store the password somewhere separate from the encrypted file itself — encrypting a file and keeping the password in the same email defeats the purpose.
- If decryption fails, double check you're using the exact original password — AES-GCM can't tell you whether it was a typo or file corruption, only that something didn't match.
- The encrypted output is a generic .enc file with no indication of its original content — this is intentional, so the file type itself doesn't leak information.
Technical specs
- Cipher
- AES-256-GCM (authenticated encryption)
- Key derivation
- PBKDF2-HMAC-SHA256, 600,000 iterations
- Salt & IV
- Freshly random per file, via the Web Crypto CSPRNG
- Metadata
- Original filename & type encrypted inside the file, restored on decrypt
- Output format
- .enc (custom container with a magic-byte header)
- Processing location
- 100% local, in your browser
Privacy & security
A file worth encrypting is, almost by definition, a file you don't want to hand to a stranger's server — so encryption that happens anywhere but your own device misses the point.
Every file and password is processed locally — never uploaded, never seen by a server.
No account, no email, no login — just a file and a password in, an encrypted (or decrypted) file out.
Nothing is retained after your download finishes; there's no copy or password waiting on a remote server.
Equally private whether you're encrypting a casual backup or a highly sensitive document.
Frequently asked questions
Is my file or password uploaded anywhere?
No. Both encryption and decryption happen entirely in your browser — your file and password are never transmitted.
What encryption does this actually use?
AES-256 in GCM mode (authenticated encryption), with the key derived from your password via 600,000 rounds of PBKDF2-HMAC-SHA256 — both are well-established, audited cryptographic standards, not custom or proprietary schemes.
Can someone recover my file without the password?
Not through this tool, and not in any practically feasible way given current computing power — that's the entire point of using AES-256 with strong key derivation.
Does it keep my original filename?
Yes. The original filename and file type are stored securely inside the encrypted content and automatically restored when you decrypt.
Can I decrypt a file encrypted with a different tool?
No. This tool uses its own file format and can only decrypt files it originally encrypted.
Is there a file size limit?
No hard limit — very large files just take longer since everything is processed on your own device.
Troubleshooting
Decryption says the password is incorrect, but I'm sure it's right
AES-GCM can't distinguish a wrong password from a corrupted or altered file — both produce the same authentication failure. Double-check for typos, extra spaces, or a different keyboard layout, and confirm the .enc file wasn't modified or partially downloaded.
It says this isn't a valid encrypted file
This tool only decrypts files it originally encrypted, identified by a header it writes into every .enc file. A renamed file of a different type, or a .enc file from a different tool, won't be recognized.
I forgot my password — can it be recovered?
No, and this is intentional. There's no backdoor or master key — if the password is lost, the file cannot be decrypted by anyone, including us.
Encryption feels slow for large files
The 600,000-round key derivation step takes a brief, deliberate moment by design (it's what makes password-guessing slow for an attacker) — actual encryption of the file itself is typically much faster.
Related searches
Landed here looking for something worded a little differently? File Encryption covers all of these too:
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