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Encryption / Decryption Tool

Encrypt and decrypt text using AES-256-GCM - a military-grade encryption algorithm. Everything happens in your browser. No data is ever sent to a server.

Algorithm: AES-256-GCM with PBKDF2 key derivation (100,000 iterations, SHA-256)  ·  Output: Base64-encoded ciphertext with embedded IV and salt  ·  Standard: NIST-approved, used by governments and financial institutions worldwide
Enter a password

About the Encryption / Decryption Tool — Online Text Encryption Tool

The Oneyfy online text encryption tool uses AES-256-GCM, the gold standard for symmetric encryption, implemented via the browser's native Web Crypto API. Your password is never used directly as a key — it is processed through PBKDF2 with 100,000 iterations and a random 16-byte salt to derive a secure 256-bit key. The encrypted output is a single Base64 string containing the salt, IV (initialization vector), and ciphertext separated by colons, making it self-contained and easy to share or store.

Developers, security-conscious individuals, and anyone who needs to share sensitive information over insecure channels use an online text encryption tool to protect their data. Common use cases include encrypting API keys before storing them in shared documents, encrypting sensitive notes before posting them to a team Slack or email thread, protecting confidential text before saving it to cloud storage, and encrypting passwords or recovery phrases before printing or storing them. Because decryption requires the same password that was used to encrypt, the ciphertext is useless without the password even if intercepted.

How to Use the Encryption Tool

  1. Select the mode using the tabs at the top: Encrypt to encrypt plaintext, or Decrypt to recover plaintext from an existing encrypted output.
  2. In Encrypt mode: enter the text you want to encrypt in the Plaintext textarea. This can be any text — a password, a note, a code snippet, or any sensitive information.
  3. Enter a strong Password / Secret Key in the password field. The strength indicator shows Weak, Fair, Strong, or Very Strong as you type. Use the eye icon to reveal the password for verification.
  4. Click Encrypt Text — the encrypted output appears in the output area as a Base64 string.
  5. Click Copy Output to copy the encrypted string. Share it via any channel — email, chat, document — knowing only someone with your password can decrypt it.
  6. In Decrypt mode: paste the full encrypted Base64 string (all three colon-separated parts) into the input area, enter the same password, and click Decrypt Text to recover the original plaintext.

Technical Details — How AES-256-GCM Encryption Works

Understanding the technical design helps you use the tool with confidence and share information about its security properties with others.

  • AES-256-GCM algorithm: Advanced Encryption Standard with a 256-bit key in Galois/Counter Mode. GCM provides authenticated encryption — it simultaneously encrypts the data and computes an authentication tag that detects any tampering with the ciphertext. A modified ciphertext fails to decrypt rather than producing corrupted plaintext.
  • PBKDF2 key derivation: Your password is not used as the encryption key directly. PBKDF2 (Password-Based Key Derivation Function 2) with SHA-256 and 100,000 iterations stretches the password into a 256-bit key. The 100,000 iterations make brute-force attacks roughly 100,000× slower than a simple hash.
  • Random salt and IV: A new random 16-byte salt and 12-byte initialization vector are generated for every encryption operation. This means encrypting the same plaintext with the same password twice produces different ciphertext each time, preventing pattern analysis.
  • Output format: The output is formatted as base64(salt):base64(IV):base64(ciphertext). All three components are required for decryption — pasting the full string preserves them automatically.

Tips for Getting the Best Results

Strong encryption is only as secure as the password protecting it and the practices around how you use the tool.

  • Use a strong, unique password: The strength indicator turns green at 16+ characters with numbers and special characters (Very Strong). A weak password like "password123" undermines even 256-bit encryption because it can be guessed by a dictionary attack. Use a password manager to generate and store a strong random password.
  • Share the ciphertext and password through different channels: Send the encrypted text via email and the password via a separate channel like a phone call or secure messaging app. If both the ciphertext and password travel through the same compromised channel, the encryption provides no protection.
  • Store the password safely before encrypting: There is no password recovery mechanism. If you lose the password, the encrypted data is permanently unrecoverable. Store the password in a password manager, not in the same document where you plan to store the encrypted text.
  • Copy the complete output string: The encrypted output includes three colon-separated sections (salt:IV:ciphertext). All three must be present for decryption to succeed. If you copy only part of the string, decryption will fail with an "Invalid format" error. Use the Copy Output button rather than manually selecting the text to ensure you get the complete string.
  • Use Decrypt mode to verify before sharing: After encrypting, switch to Decrypt mode, paste your ciphertext, enter your password, and verify the decrypted text matches your original. This confirms the password and ciphertext are correct before you rely on them or share them with someone else.

Why Use an Online Text Encryption Tool

A browser-based encryption tool requires no software installation, works on any operating system, and uses cryptography that is native to the browser — not a third-party library. Because the Web Crypto API is built into every modern browser, the encryption code runs entirely client-side. No text, passwords, or encrypted output are ever transmitted to any server. The tool also works offline once the page has loaded.

Developers use it to quickly encrypt sensitive strings before storing them in shared wikis or version control. Security professionals use it to share confidential notes over insecure email. Non-technical users who need to send a sensitive password, serial number, or personal information to someone can encrypt it without setting up PGP or other complex tools. The password strength indicator and clear instructions make it accessible to users without a cryptography background.

Frequently Asked Questions about Online Text Encryption Tool

AES-256-GCM is a symmetric encryption algorithm using a 256-bit key in Galois/Counter Mode. It is a NIST-approved standard used by banks, governments, and internet protocols like TLS (HTTPS) worldwide. GCM provides both encryption and authentication — the authentication tag means any modification to the ciphertext (even a single bit) causes decryption to fail with an error rather than producing silently corrupted plaintext. This tamper-detection property is what makes it the preferred mode over older modes like AES-CBC.
PBKDF2 (Password-Based Key Derivation Function 2) is a standard algorithm that converts a human-chosen password into a fixed-length cryptographic key. Using 100,000 iterations means an attacker must run PBKDF2 100,000 times for every password guess. A modern GPU that can compute billions of simple SHA-256 hashes per second is reduced to thousands of PBKDF2 attempts per second, making dictionary and brute-force attacks on even moderately strong passwords computationally impractical.
Yes — the encrypted Base64 output is safe to share via email, Slack, public documents, or any other channel, provided your password remains secret. Without the password, the ciphertext is computationally infeasible to decrypt with current technology. The security of AES-256 is not undermined by the ciphertext being publicly visible — security comes entirely from the secrecy of the password, not the secrecy of the algorithm or the ciphertext structure.
There is no recovery mechanism. If you lose the password, the encrypted data is permanently unrecoverable — by design. This is what makes the encryption trustworthy: even if someone gains access to the server (which has no data anyway, since everything is client-side), or even if the tool's developers were compelled to assist, they could not recover your data without the password. Always store your encryption password in a dedicated password manager before encrypting important data.
No. All encryption and decryption happens entirely in your browser using the Web Crypto API — a set of cryptographic primitives built directly into modern browsers. Your plaintext, password, and encrypted output never leave your device. There is no server involved in any step of the process. You can verify this by disconnecting from the internet after loading the page and confirming that encryption still works fully offline.
Yes, completely free with no account or sign-up required. There are no usage limits, no file size restrictions on the text you can encrypt, and no premium tier. Since all processing happens in the browser, there are no server costs, and the tool remains free for all users indefinitely.
The tool encrypts text only. To encrypt a file, you could encode the file as Base64 text first, then encrypt that text string, and reverse the process to decrypt. However, for file encryption, dedicated tools like 7-Zip (with AES-256 password protection) or VeraCrypt are better suited, as they handle large binary files more efficiently than a text-based tool.
Yes. The Web Crypto API used for encryption is available in all modern mobile browsers including Safari on iOS (version 11+) and Chrome on Android. The encrypt and decrypt modes, password strength indicator, and copy button all function identically on mobile. You can encrypt text on your laptop and decrypt it on your phone (or vice versa) using the same password.