What file types can I encrypt?

Any file at all -- documents, images, archives, videos -- since the tool operates on raw bytes rather than parsing the file's format. The encrypted output is a generic binary file (.enc) regardless of what you started with.

How do I get my original file back?

Switch to Decrypt mode, choose the .enc file, enter the exact same passphrase you encrypted it with, and click Decrypt File -- the original file downloads with its original name restored (the .enc suffix is stripped automatically).

Why does the download start automatically?

Both encryption and decryption produce a new file as the direct result, so this tool triggers a browser download immediately rather than displaying the (typically large, binary) result on the page -- the same behavior as any file-processing tool that hands you back a modified file.

Is there a file size limit?

The whole file is read into memory and encrypted in one pass, so very large files (many gigabytes) may be slow or hit your browser's memory limits -- this tool is best suited for typical document, image, and archive sizes rather than huge media files.

Is my file uploaded anywhere?

No. Encryption and decryption both happen entirely in your browser using the Web Crypto API -- the file is never uploaded, transmitted, or stored anywhere outside your own device.

Encrypt or Decrypt a File — Free AES-256-GCM Tool

Drop or choose a file, enter a passphrase, and pick Encrypt or Decrypt — the File Encrypter Decrypter runs it through AES-256-GCM entirely inside your browser and hands you a downloadable, transformed file when you click Encrypt File (or Decrypt File). Nothing is ever uploaded to a server, so you can protect a document or archive without sending it anywhere.

Whether you need to protect sensitive information before sending files over the cloud or simply want to lock down personal documents on your drive, this file encrypter decrypter gives you military-grade encryption without installing any application. Every file you process is handled entirely in your browser — files are processed in memory, never logged, and never retained — so you retain full control over your data at all times. The result is fast, trustworthy online file encryption that anyone can use in a matter of seconds.

Encrypt Your File Online — Secure, Instant & Password-Protected File Encrypter Decrypter

Protecting your documents, images, PDFs, and text files has never been more straightforward. This file encryption tool follows modern best practices recommended by NIST and OWASP, applying authenticated encryption to every file you upload. Files never leave your session unencrypted, and the encrypted output is available for instant download the moment processing finishes. This freeware browser-based approach means you can secure files and perform a secure transfer without installing anything.

How AES-256 Encryption Secures Your Data During the Encryption Process

AES-256 (Advanced Encryption Standard) is a symmetric encryption algorithm that uses a single 256-bit key for both locking and unlocking data. It is the same cipher trusted by governments, financial institutions, and cybersecurity professionals worldwide. When you supply a password, the tool does not use it directly as a secret key. Instead, it applies PBKDF2 key derivation — specifically PBKDF2 with HMAC-SHA256 — combined with a unique initialization value and a random salt, so your password is password-strengthened against brute-force attacks before any protection begins.

The cipher mode used is AES-256-GCM (Galois/Counter Mode), a form of authenticated cryptography that simultaneously provides data confidentiality and integrity protection. This means the protected output includes a cryptographic authentication tag — a type of cryptographic MAC (similar to a message authentication code) — that detects any file tampering before the recovery stage begins. If even a single byte of the protected output is altered, AES-GCM integrity verification fails and restoration is refused, protecting you from tampered data.

The encryption flow from plaintext to ciphertext works as follows:

File upload: Your file — up to max 10MB — is loaded into browser memory. Secure in-memory processing means your source document never touches a remote disk.
Password-based key derivation: Your passkey passes through PBKDF2 with a unique random salt, producing a 256-bit AES key. Alternatives like Argon2, bcrypt, and scrypt serve a similar purpose in other contexts, but this tool uses PBKDF2 for broad compatibility.
AES-256-GCM encryption: The derived key and a freshly generated initialization vector protect your file data, converting plaintext to ciphertext with built-in authentication.
Instant download: The protected output — including the salt and IV as metadata — is packaged and downloaded immediately. The tool applies no file storage of any kind; files are discarded from memory once your download begins.

Privacy note: Files are never stored, never logged, and never retained. Your secret key and derived keys exist only in memory during processing. This is a genuinely privacy-friendly, no software required experience built for data protection.

3 Simple Steps to Encrypt Any File with This Encrypter

Choose your file: Click the file upload button and select any supported format — documents, images, PDFs, or text files — up to 10 MB. A file preview is shown before the process starts.
Set your secret passkey: Enter a strong password (your key phrase or secret passkey). This is your decryption passkey — store it safely. Password recovery is impossible if it is lost password.
Download your protected output: Click encrypt. The file processed in memory is immediately converted to a protected format and downloaded. Your encrypt .enc file is ready for safe storage or secure file sharing.

Decrypt Your File Online — Restore Access to Encrypt and Decrypt File in Seconds

Recovering your original data is just as straightforward as protecting it. Upload the protected output you previously created, supply the same password, and the file decryptor reconstructs your unprotected document instantly. Because this tool uses authenticated encryption (AES-GCM), it verifies file integrity before releasing any data — if the file has been modified or if you enter an incorrect passphrase, a decryption fail is reported before any corrupted output is produced.

Decryption Flow: From Encrypted File Back to Original Using File Decryption

Upload the encrypted file: Select the .enc file produced during encryption. This is your protected archive — do not rename it or change its file extension, as the metadata embedded at the start of the file is required for restoration.
Enter your password: Provide the same secret key / passkey used during the original process. The tool performs key derivation again, regenerating the identical output using the stored salt.
Authenticated verification: AES-GCM integrity checks the authentication tag. If the tamper check fails — meaning any byte differs from the original — the operation is aborted to prevent file corruption.
Instant download of the original: If verification passes, your file download begins immediately. The recovery stage outputs the restored document — in-memory processing means the result is never persisted on any server.

Running File Decryption from the Command Line with FileCryptor

For developers and power users who prefer a terminal, the open-source FileCryptor (file cryptor) Python program — available in its public repository on GitHub — lets you retrieve protected documents directly from the terminal. This developer tool is a CLI-based application that mirrors the same AES file encryption logic and supports text encrypt and text decrypt operations. Here is an example restore command:

python filecryptor.py --decrypt --file sensitive.docx.encrypted --password yourpassword

The tool reads the protected archive, extracts the embedded initialization values from the metadata, derives the decryption credential using PBKDF2, and writes the source document back to disk — naming it without the .encrypted suffix. Running it with --help at the terminal prompt lists all available parameters:

python3 filecryptor.py --help
usage: filecryptor.py [-h] [-e] [-d] [-p PASSWORD] [-r] [-a ALGORITHM] dosya_adi

File encryption and decryption tool

Tip: On modern desktop editions of Windows, you can also encrypt contents to secure data via File Explorer — right-click any file, open Properties, click the General tab, then select Advanced. In the advanced attributes dialog, tick Encrypt contents to secure data and click OK. This uses Windows EFS rather than AES-GCM, but it is a useful file management option on a Windows computer. Note that EFS requires administrator access on older releases such as Windows Vista.

Core Capabilities: What This Online File Encryption & Decryption Tool Does

This versatile file encrypter decrypter is built around proven cipher standards. Whether you need to encrypt documents, encrypt images, encrypt PDFs, or encrypt text files, the same hardened pipeline handles every supported format and enables secure encryption of all common file types. Below is a full summary of its features. As freeware, the browser edition costs nothing to use.

AES-256 (Advanced Encryption Standard): Industry-leading 256-bit AES encryption — the same cipher used for large file encryption in enterprise and government environments.
Password-based encryption: A secret passkey you choose becomes the basis for robust key derivation. No pre-shared certificates are required.
In-memory processing: Files are never stored on any server. They are loaded, processed, and discarded entirely within your session — keeping your data private.
No file storage: There is no server-side database, no upload queue, and no logging of file contents, passwords, or key material.
Instant download: Your protected output is available for download as soon as the cipher finishes — typically under one second for most files.
Multi-file batch support: Protect or restore documents in batches using the CLI — process file1.txt, file2.txt, and file3.txt simultaneously with a single shared password.
Filename encryption: The CLI supports optional filename encryption, replacing meaningful filenames with a meaningless filename for additional obfuscation.
Portable encryption: Run the program binary from a USB key without any installation — making it a genuinely portable option that can run without installing anything on the host machine.
Open source: The FileCryptor repository is fully open source, published under a permissive license, and accepts community contributing.

Encryption Algorithms & AES-256 Key Derivation Supported

The primary cipher is AES-256-GCM — an authenticated cryptography mode that combines the advanced encryption standard with a Galois/Counter mode tag for data integrity. Unlike the simpler XOR based key cypher used in some educational tools (where each character integer is XOR'd with the next character in a key phrase and output as a comma separated list of integers — a simple cipher based on the exclusive or / XOR bitwise operation), AES-GCM is practically irreversible without the correct credential. The XOR cipher approach, while useful for teaching encoding and decoding concepts, offers no real data protection and should not be used for sensitive documents.

The CLI exposes an --algorithm flag so you can select your cipher explicitly. Currently the supported value is AES256. The secret key is never stored — it is derived at runtime and exists only as a transient value in memory.

Batch File Encryption & Multi-File Support for Fast Encryption

For teams or workflows that need to protect documents in bulk, FileCryptor supports passing multiple file paths in one command. Each document is individually protected with its own unique salt and initialization vector, even when they share the same password — ensuring that identical input text in two files produces completely different output text (and therefore different ciphertext). This approach supports secure files sharing via channels without leaking correlation patterns, making it ideal for a secure transfer workflow.

Batch multi-file encryption example — encrypting three files simultaneously with a shared password:

python filecryptor.py --encrypt --file file1.txt file2.txt file3.txt --password sharedpassword

Algorithm-specific encryption example — explicitly selecting AES256 for data.txt:

python filecryptor.py --encrypt --file data.txt --password mypassword --algorithm AES256

The protected output for each file follows the naming convention <original_filename>.encrypted — for example, document.txt becomes document.txt.encrypted. You can also protect entire folder contents recursively and restore folder trees in a single pass using the -r (recursive) flag, making it efficient for secure storage of entire project directories. The tool also supports basic file compression workflows when combined with archive utilities before encryption.

AES-256 vs RSA vs PGP: Choosing the Right Encrypt File Online Method

Not every encryption scenario calls for the same approach. Understanding the trade-offs between symmetric encryption, asymmetric encryption (RSA), and PGP encryption helps you pick the right tool for each task. The table below compares the three most common methods across the dimensions that matter most for practical file protection.

Feature	AES (This Tool)	RSA	PGP
Key type	Symmetric (single secret key)	Asymmetric (public/private pair)	Hybrid (RSA + AES internally)
Speed	Fast encryption — ideal for large files	Slow — impractical for large data	Fast for file data (AES core)
Best use case	Password-protected file sharing, backups, secure storage	Encrypting small secrets, credential handoff, digital signatures	Sending to multiple recipients, email, multiple recipients
File size suitability	Excellent — supports large file encryption	Poor — public-key methods are not suited for bulk data	Good — uses AES internally for the payload
Complexity	Low — password only; no credential infrastructure needed	High — requires certificate chains and key administration	Medium — requires keyring setup and credential sharing
Message authentication	Built-in via AES-GCM authentication tag	Separate step (requires digital signatures)	Built-in via PGP file encryption signature
Password-based	Yes — password-based key derivation via PBKDF2	No — relies on public/private key pairs	Optional — supports both passphrase and key-pair modes

When to Use Symmetric vs Asymmetric Encryption for Encrypted Files

AES-256 excels when a single party protects and later restores their own data, or when two parties share a password out-of-band. Its model is simple: whoever holds the secret passkey can lock and unlock content. RSA encryption (an asymmetric algorithm based on public/private key pairs) is the right choice when you need to send a credential to a recipient without ever transmitting it in the open — for example, during key handoff or when generating digital signatures for document authentication. PGP file encryption (which combines asymmetric and symmetric methods) is best when each recipient holds their own private key — for instance, securely sending files to colleagues who each have a PGP keyring.

From a data-protection standpoint, information assurance professionals recommend AES-GCM for most file-level use cases because it combines confidentiality with integrity verification — a property that simpler modes like AES-CBC lack. The tag in AES-GCM acts as a form of cryptographic MACs, confirming that the ciphertext has not been altered since the original operation.

When This File Encryptor Is Not the Right Choice

Despite its strength, this tool is not appropriate for every scenario. Be aware of the following limitations:

Multi-recipient sharing: If you need to send a protected file to multiple recipients who each hold different keys, use PGP encryption. Password-based tools require all recipients to know the same password, which is a digital risk.
Password storage: Never use this approach to protect stored passwords. Purpose-built credential-hashing functions like Argon2, bcrypt, or scrypt are designed specifically for that task with tunable cost factors.
Public-key use cases: When you need RSA-based operations, ECC handoffs, or digital signatures, use a library that implements asymmetric primitives correctly.
Disk-level encryption: Tools like VeraCrypt, BitLocker, and FileVault (macOS) provide full-disk and volume-level protection for an entire drive — including the operating system. This tool handles individual files, not volume-layer protection.
Enterprise key management: Large organisations with compliance requirements need dedicated credential-administration infrastructure, access control policies, and audit trails — well beyond the scope of a browser-based tool.
Cloud storage sync: Files stored in OneDrive, Google Drive, or other cloud services may be re-uploaded after restoration. Protect locally before uploading rather than relying solely on the provider's built-in safeguards.

Note on WinZip / SecureZip compatibility

Some third-party applications such as WinZip 9 (and later), SecureZip, and 7-zip support AES inside ZIP archives — making them both a compression utility and an encrypter. If you need to compress and protect or securely archive a large set of files, these tools are winzip compatible and securezip compatible. They can also encrypt filenames, storing files with an eoc extension, and support unicode enabled file paths. They are a good choice for producing a smaller file size alongside protection, and they support keeping the original file or choosing to delete after encrypting / delete after decrypting.

Installation, Setup & Command-Line Usage for the Encrypt and Decrypt Files CLI

The browser-based version of this tool requires no installation whatsoever — it is a true no software required experience. For the command-line FileCryptor program, you will need Python and a few dependencies. Here is how to get started from the GitHub public repository.

Installation & Dependency Setup — Requirements and Getting Started

Clone the repository files from GitHub:

git clone https://github.com/HalilDeniz/FileCryptor.git

Install the required dependencies listed in requirements.txt:

pip install -r requirements.txt

The requirements file pulls in the cipher libraries needed for AES-256 encryption and key derivation. Once installed, the application is ready to protect or restore documents immediately. You can also copy the binary to a USB key and run it as portable software on any machine — run it via cmd.exe on Windows or a terminal on macOS/Linux — making it ideal for portable scenarios where you need to work on a machine without internet access or where you prefer not to install anything permanently. The latest commit history and full repository files are visible on the project's GitHub page, along with tagged releases.

Command-Line Usage Examples for AES-256 Encryption and File Decryption

Single file encryption — protecting sensitive.docx with a password:

python filecryptor.py --encrypt --file sensitive.docx --password yourpassword

The protected output is saved as sensitive.docx.encrypted. The source document remains on disk unless you add a flag to remove it after the operation. The passphrase you choose becomes the root of the entire key hierarchy — guard it carefully.

Batch multi-file encryption — file1.txt, file2.txt, file3.txt with a shared passphrase:

python filecryptor.py --encrypt --file file1.txt file2.txt file3.txt --password sharedpassword

Each file is individually protected with its own random salt and IV. The output for each is a separate .encrypted file — no trailing backslash is needed in the file paths.

Algorithm-specific encryption — explicit AES256 flag for data.txt:

python filecryptor.py --encrypt --file data.txt --password mypassword --algorithm AES256

This is the recommended form when you want the invocation to be unambiguous in scripts or unattended automation. The recovery passphrase must match exactly when you later run:

python filecryptor.py --decrypt --file data.txt.encrypted --password mypassword

The restoration stage reads the metadata block at the head of the protected archive, extracts the salt, derives the key, and restores your source document. The output in the CLI is simply the restored file written back to disk. Note: running the tool from a folder that requires elevated privileges may fail on Windows without administrator permissions — always check your properties settings or run your terminal as an administrator. Confirm-password prompts can be added as a safety measure in interactive mode to prevent typos.

Common Errors, Troubleshooting & File Encryption Security FAQ

Even a well-designed tool can produce unexpected results if the inputs are wrong. Below are the most common problems users encounter when they encrypt and decrypt files, along with authoritative fixes. This section also addresses the most frequent questions about online protection, data safety, and digital safety when using a browser-based or CLI file encrypter decrypter.

Troubleshooting Encrypt & Decrypt Failures — File Decryption Errors

Incorrect passphrase entered during decryption: If you supply the wrong password, PBKDF2 derives a completely different key — AES-GCM authentication fails immediately and decryption fail is reported. No corrupted output is produced.
Fix: Use the exact same passphrase (including case, symbols, and spaces) as the original. There is no password retrieval or password recovery mechanism — if your lost password cannot be recalled, the data is unrecoverable.
Protected archive was modified or corrupted: AES-GCM integrity is absolute — any single-byte change causes authentication to fail. Corruption during transfer, compression, or re-encoding produces the same result.
Fix: Transfer protected archives using binary-safe channels. Do not open, rename, compress, or edit the .encrypted file between the two operations. Files discarded after deletion cannot be recovered from a corrupted copy.
Unsupported file format or size exceeded: Files above the max 10MB limit are rejected by the browser tool. Some file types may not render a file preview.
Fix: Use the CLI for large file encryption — it has no hard size cap. Check supported formats in the tool documentation.
Missing dependencies / startup failure: Running the CLI without completing pip install -r requirements.txt causes import errors.
Fix: Re-run installation in the same virtual environment. Verify your Python version meets the stated requirements. On recent or older Windows releases, ensure you are not blocked by OS policies or antivirus scanning that quarantines the program binary.
Confirm password mismatch: When using interactive mode, a confirm-password prompt may appear. Mismatched entries abort the operation before any output is written.
Fix: Re-enter your passphrase carefully. Use a credential manager to generate and store a strong password — never rely on memory alone for a decryption passkey that protects critical data.
Unauthorised access after decryption: Restoring a file onto a compromised machine exposes your data to malicious actors or malware.
Fix: Ensure your environment is free of threats before restoring sensitive information. Use endpoint protection and consider full-disk encryption via VeraCrypt or BitLocker for protection at rest.

FAQ: File Encryption Security, Usage & Privacy

Is my file stored on the server after I encrypt or decrypt it?

No. This tool uses in-memory only processing. Your file is loaded into session memory, processed, and immediately discarded. Files are never stored, never logged, and never retained — not even temporarily. There is no server-side database, no upload log, and no credential retention of any kind. It is a genuinely privacy-friendly service aligned with best-practice data-handling standards.

What encryption standard does this file encryption tool use?

It uses AES-256-GCM — the advanced encryption standard with a 256-bit key in Galois/Counter Mode. This delivers 256-bit AES encryption with built-in message authentication, making it both a cipher and a cryptographic MAC. The session key is derived from your password using PBKDF2 key derivation with a hash-based authentication code and a unique random salt. This follows NIST and OWASP recommendations for robust key derivation.

Can I encrypt multiple files at once?

Yes — via the CLI FileCryptor program. Pass multiple filenames to the --file flag in a single command. Each document in the batch is individually protected with its own salt and IV, so even if two files have identical content, their outputs differ completely. The browser tool currently handles one file per session.

What if I forget my password?

There is no forgotten-password workaround and no retrieval path. AES-256 is designed to be practically irreversible without the correct decryption credential. Your decryption passkey is the only mechanism for recovery. Store it in a reputable credential manager and always confirm the secret key before protecting irreplaceable data.

Is this tool safe for sensitive documents and secure data?

Yes, for the vast majority of personal and professional use cases. The tool implements authenticated encryption (AES-GCM), PBKDF2-based key strengthening, and in-memory processing — all recommended by leading cybersecurity bodies. Your data is handled with protection in mind at every stage. That said, for regulated industries requiring enterprise credential administration, formal access control, or compliance auditing, consult an information assurance professional and consider purpose-built solutions. For everyday file protection — including sending files via email, storing on cloud services, or securing large video files before sharing — this online tool is safe and secure.

How does Windows 11 built-in file encryption compare?

On Windows 11 or other Windows editions, you can encrypt contents to secure data through File Explorer by right-clicking a file, opening Properties, and navigating to the advanced attributes section. This uses the Encrypting File System (EFS), which is tied to your Windows login — not a portable protected format you can move between machines. For cross-platform, password-protected archives you can share or store anywhere, the AES-GCM approach is more flexible and provides stronger confidentiality guarantees. Data protection on Windows is also covered by BitLocker (for full-disk coverage) and OneDrive Personal Vault (for cloud storage with extra layers). Windows settings also let you manage file-management permissions and access policies at the OS level.

For developers: The open source FileCryptor program is a developer tool written in Python, available as a CLI application on GitHub. The repository welcomes contributing, ships with a clear license, and maintains a full commit history. It is an excellent foundation for building file decryption and file protection into automated workflows, CI pipelines, or backup scripts. Check folders and files in the repository for getting started guides and operation examples. Take control of your data with a tool that is transparent, auditable, and aligned with modern online-protection principles — a safer, easy steps approach to information assurance for every developer.

Frequently Asked Questions

What file types can I encrypt?: Any file at all -- documents, images, archives, videos -- since the tool operates on raw bytes rather than parsing the file's format. The encrypted output is a generic binary file (.enc) regardless of what you started with.
How do I get my original file back?: Switch to Decrypt mode, choose the .enc file, enter the exact same passphrase you encrypted it with, and click Decrypt File -- the original file downloads with its original name restored (the .enc suffix is stripped automatically).
Why does the download start automatically?: Both encryption and decryption produce a new file as the direct result, so this tool triggers a browser download immediately rather than displaying the (typically large, binary) result on the page -- the same behavior as any file-processing tool that hands you back a modified file.
Is there a file size limit?: The whole file is read into memory and encrypted in one pass, so very large files (many gigabytes) may be slow or hit your browser's memory limits -- this tool is best suited for typical document, image, and archive sizes rather than huge media files.
Is my file uploaded anywhere?: No. Encryption and decryption both happen entirely in your browser using the Web Crypto API -- the file is never uploaded, transmitted, or stored anywhere outside your own device.