What format is the encrypted output?

A single Base64 string containing the random salt (16 bytes), the random IV/nonce (12 bytes), and the AES-256-GCM ciphertext (which includes its own authentication tag) concatenated together -- self-contained, so you only need to copy one value to decrypt later, with no separate salt or IV to track.

Why does decryption need the exact same passphrase?

The passphrase is run through PBKDF2 (250,000 iterations, SHA-256) together with the salt stored in the encrypted output to derive the actual AES-256 key -- get the passphrase even slightly wrong and the derived key is completely different, so decryption fails outright rather than producing garbled text (GCM's built-in authentication tag catches this and reports a clear error instead).

Why 250,000 PBKDF2 iterations?

It's a deliberate slowdown that makes brute-forcing a weak passphrase significantly more expensive for an attacker, while still completing in a fraction of a second for a legitimate user with the correct passphrase -- roughly in line with current OWASP recommendations for PBKDF2-SHA256.

Is this the same as a password manager's encryption?

It uses the same well-established building blocks (AES-256-GCM, PBKDF2) that many password managers rely on, but this tool is a simple one-off encrypt/decrypt utility, not a full vault -- there's no key storage, no session, no sync. Use it for sharing a short secret text securely, not as a replacement for dedicated encrypted storage.

Is my text or passphrase sent anywhere?

No. Both encryption and decryption happen entirely in your browser using the Web Crypto API -- nothing is transmitted, logged, or stored. Reload the page and everything is gone.

Encrypt or Decrypt Text — Free AES-256-GCM Tool

With the Text Encrypter Decrypter, you switch between Encrypt and Decrypt mode, type a passphrase plus the text you want to protect, and the tool returns the encrypted or decrypted output right below it using AES-256-GCM. Your passphrase never leaves the browser — it's run through PBKDF2 with 250,000 iterations to derive the actual encryption key, so you get real protection for notes, credentials, or messages you need to share safely.

Whether you need to protect sensitive information before sharing it over a public channel or simply want to experiment with data encryption concepts, this free online text encryption and decryption tool gives you bank-grade encryption results instantly — no sign-up required, no setup, and no server interaction. As a browser-based text encrypter decrypter, it runs entirely client-side, so your original message, your key, and every protected result stay exclusively in your browser — never stored and never transmitted to any server. Whether you're a developer encrypting API payloads, a security professional testing configuration values, or someone exploring encryption techniques for educational use, this encrypt online utility delivers the power of advanced protection in one click.

How to Use a Text Encrypter Decrypter to Encrypt and Decrypt Online

At its core, encryption is the process of converting a readable message — the original text — into an unreadable form called scrambled output, so that unauthorized parties cannot access its contents. Decryption is the reverse: given the correct key, it recovers the original message from the protected output. This text encrypter decrypter handles both operations instantly, and you can also decrypt online with the same tool.

Understanding Plaintext and Encoded Output in Symmetric Encryption

When you paste your source content into the entry field, you are providing the original readable material. Once processed, the tool returns the scrambled result in the result field, a protected output that is meaningless without the matching key. For symmetric encryption using a symmetric key like AES, the same encryption decryption key is used for both operations — making key handling the most critical part of your protection chain.

This tool supports a custom or auto key workflow. You can provide your own passphrase (a key phrase of your choosing) as a custom key, or allow the tool to generate a cryptographically secure key automatically using a random number generator. The auto key option is ideal when you need strong random keys without having to create one manually. To decrypt later, you must supply exactly the same passphrase and algorithm — so record both securely in a password-protected location.

You can use this tool to encrypt strings, encrypt JSON, encrypt YAML, encrypt config files, encrypt API payloads, encrypt logs, and any other text value. There are no limits imposed on source content length, though be aware that very large strings may affect string size in bytes when storing in database columns or hitting API payload limits. Because all processing is browser-based and runs in browser memory, your data achieves complete data privacy — no account, no login, and no third-party access. This makes it an ideal text security solution for developers and individuals alike.

Caesar cipher worked example
Original message: MEET ME AT THE PARK
With a +3 letter shift (fixed shift applied to every character):
Encrypted result: PHHW PH DW WKH SDUN
The same key (shift of 3) is applied in inverse manner to recover the original message.

Before you share: Always run a decrypt test before distributing your protected message. Confirm the recipient has format support for the same algorithm and possesses the same passphrase — delivered through a different channel from the protected result. Copy the result from the output field, then switch to the decrypt tab and paste it in to verify successful decryption before sending.

Encrypt text online — paste any string and receive protected output immediately.
Decrypt text online — paste the encoded message and the key to recover the original message.
Works as both an encrypter and a decrypter — a single online tool for both directions.
Supports password-based derivation so your human-chosen passphrase seeds a full 256-bit key.
Completely browser-side — a true web app requiring no installation and no legacy CryptoJS dependencies on your system.
Functions as a developer tools resource and testing tool for quick data transformations.
Available for personal use, educational use, and light professional use.

Supported Algorithms, Key Sizes, and Encryption Online Protection Levels

Choosing the right encryption algorithm is as important as choosing a strong key. This online encryption tool — sometimes called a cypher or key cypher program — supports multiple algorithms on this page, ranging from modern government-grade encryption standards to legacy format options retained for interoperability with existing deployments and older-format workflows.

Ancient and Classical Ciphers — The Origins of Encryption

The history of keeping messages secret stretches back to ancient Egypt, where scribes modified hieroglyphs to obscure meaning. The Greeks used the scytale — a rod-based transposition device — while the Roman Empire popularised the Caesar cipher, a simple substitution method applying a fixed shift to a substitution alphabet. During the Renaissance, the Vigenère cipher introduced multiple substitution alphabets, making frequency analysis harder. The Grille cipher, or Cardan grille, used a physical template as a simple cipher to reveal hidden text. Techniques like steganography — hiding the very existence of a message — also emerged during this era as an alternative to encryption.

Caesar alphabet shift (shift = 3):
Plaintext: ABCDEFGHIJKLMNOPQRSTUVWXYZ
Ciphertext: DEFGHIJKLMNOPQRSTUVWXYZABC

The Caesar cipher performs a letter shift — each character in the source content is mapped to the letter three positions ahead in the substitution alphabet. Because there are only 25 possible key combinations, this simple cipher offers no real data protection today. By the early 20th century, mechanical encryption devices like the Enigma — an electromechanical rotor machine used during World War II — raised complexity dramatically, until Alan Turing and his team cracked it through pioneering cryptanalysis, marking a turning point in information protection.

Modern Cryptography Standards — AES Encryption and Beyond

Modern encryption relies on mathematical algorithms too complex for brute-force attacks. The Advanced Encryption Standard (AES) replaced DES in the early 2000s after NIST standardisation, and today it secures nearly all digital communication — from banking security and messaging security to cloud storage and internet traffic. AES is a symmetric algorithm (same key to encrypt and decrypt) and a block cipher, operating on fixed-size blocks of data with padding added as needed.

The recommended default for new work is AES-256-GCM. The GCM (Galois/Counter Mode) mode acts as an authenticated encryption scheme: it computes a message authentication code (MAC) — specifically a Poly1305-style verification tag — that must verify before any decrypted content is returned. This provides both confidentiality and data integrity. An initialization vector (IV) is generated per-operation to ensure identical source content produces different protected output every time, preventing pattern analysis. The aes-gcm envelope (sometimes called an eoe1 envelope or versioned envelope) bundles the algorithm, salt, the nonce, and password derivation settings so the matching decrypt operation can identify algorithm parameters automatically.

AES-256-CBC and aes-cbc mode remain available as an explicitly selected option for interoperability — for example, when working with existing legacy CryptoJS-protected values or systems that require a specific legacy method. The CBC (Cipher Block Chaining) mode works by XOR-ing each block with the previous scrambled block before encryption, with a nonce seeding the chain. Both aes-256-cbc and aes-128-cbc variants are supported; the difference lies in key size — 256 bits versus 128 bits — which directly affects the number of possible key combinations an attacker must exhaust.

Additional supported algorithms on this page include:

AES-128-CBC — AES with a 128-bit key in CBC mode; fast and widely interoperable, suitable for many standard applications.
AES-256-GCM / AES-GCM — authenticated encryption with integrity checking via the GCM mode; the recommended default for all new string encryption.
AES-256-CBC — strong block cipher mode; use when the recipient system requires CBC format support.
ChaCha20 (with Poly1305 for identity verification) — a modern stream cipher offering excellent protection performance, particularly on devices without hardware AES acceleration.
Camellia (including Camellia-128, Camellia-192, Camellia-256) — a Japanese standard with comparable strength to AES; camellia-128-cbc, camellia-192-cbc, and camellia-256-cbc modes are supported for interoperability.
ARIA (including ARIA-128, ARIA-192, ARIA-256) — the Korean national encryption standard; variants such as aria-128-cbc, aria-192-cbc, and aria-256-cbc cover a range of key size requirements.
CAST / CAST5 — a flexible and industry-standard block cipher used in various industry security standards.
SEED — widely adopted in specific regional deployments and international encryption standards.
Blowfish — a fast, legacy-friendly symmetric algorithm with variable key length; still found in some existing system implementations.
IDEA — the International Data Encryption Algorithm, a 64-bit block cipher used historically in PGP email protection.
3DES / DES-EDE3 — Triple DES applying the older DES algorithm three times for greater strength; available strictly as a historical format for legacy interoperability.
RC2, RC5 — older variable-key algorithms included for legacy format support; RC2-40 and RC2-64 sub-variants exist alongside standard RC2.
XOR-based key cypher — a xor cipher / xor based approach where each character in the source content is treated as an integer (you can treat as integer any character input), exclusive or'd (XOR) with the next character in the key phrase (also treated as an integer). The results are collected as an integer output, then output as a comma-delimited list — a set of integers separated by commas — in the result field. Decryption works in an inverse manner: each integer is read from the comma-delimited list, XOR'd with the next character of the key, then converted to character and appended output to the result field. This is a foundational teaching example of xor key cypher logic and bitwise operations.

AES-256 encryption is widely regarded as the gold standard of symmetric encryption — the same government-grade encryption level used by financial institutions worldwide. A full 256-bit key means \(2^{256}\) possible keys, a number so large that no classical hardware could brute-force it within the lifetime of the universe. Note that key size does not determine the size of protected data directly; rather, padding, the nonce, the verification tag (in GCM/CCM modes), and base64 representation of the binary output collectively determine how much larger the protected result is versus the original source. For a short sentence, expect the output to be roughly 60–100 bytes larger than the source — relevant when sizing database columns or working within API payload limits. The aes-wrap key-wrapping mode is also available for wrapping other encryption keys securely.

Algorithms to Avoid — Outdated and Unsecure Algorithms

Several outdated algorithms remain in the list for historical reference and legacy interoperability but should never be chosen for protecting real sensitive data:

DES (Data Encryption Standard) — uses a 56-bit key, trivially breakable with modern hardware in hours. Replaced by AES for all modern uses.
RC4 — a fast stream cipher with serious known weaknesses and cryptographic attacks; banned from TLS since 2015.
RC4-HMAC-MD5 — combines a broken stream cipher with MD5 for a message authentication code (HMAC); doubly problematic.
DESX / DES-EDE3 — extensions of DES that add marginal strength but still fall far short of AES key size protection.
RC2-40, RC2-64 — short-key variants with trivially small keyspaces, originally designed for export restrictions.
ECB mode (ECB) — any algorithm in Electronic Codebook mode encrypts identical blocks to identical protected values, leaking patterns. Avoid for any structured data.

These unsecure algorithms are listed here only to support interoperability with older-format data. For any new encryption or encrypt strings workflow, stick to AES-256-GCM or AES-256-CBC. The broader supported list also includes modes like CFB, OFB, CTR, CCM, OCB, and XTS for specialised use cases — for instance, one XTS variant is optimised for disk-level file encryption at rest, while CTR mode turns AES into a stream cipher suitable for encrypt logs or streaming data scenarios. Security professionals can also use these modes to encrypt files and decrypt files in specialised workflows.

Quantum-Safe Encryption — An Emerging Consideration

Quantum computers threaten some existing cryptographic systems — particularly public-key schemes like RSA encryption and ECC encryption that rely on the difficulty of factoring large numbers. Symmetric encryption such as AES-256 is more resilient: quantum attacks (Grover's algorithm) effectively halve the key protection level, reducing a 256-bit key to roughly 128-bit equivalent strength — still computationally secure. Newer post-quantum approaches under active standardisation by NIST include lattice-based methods, code-based methods, and digest-based schemes. These methods aim to be quantum-safe encryption — resistant to both classical and quantum adversaries. The field remains in active development; adopting AES-256 today gives you a future-proof foundation while quantum-safe standards mature. Public-key schemes used for key exchange should be monitored closely as post-quantum standards finalise.

Encryption Best Practices You Should Follow When Using Any Encrypt and Decrypt Tool

Using a powerful encryption tool is only half the equation — proper implementation and disciplined key handling determine whether your data protection holds up in practice. The following encryption best practices reflect guidance from NIST, OWASP, and leading cybersecurity frameworks, and apply whether you're encrypting a single message or architecting a data-protection system.

Use established algorithms. Always choose battle-tested, peer-reviewed strong algorithms — AES-256 for symmetric encryption, and RSA or ECC encryption for public-key exchange. Never rely on custom ciphers or proprietary ciphers invented in-house; obfuscation is not protection, and homegrown designs almost always contain exploitable flaws.
Use strong, random keys. Your encryption key and decryption key should be at least 256 bits and generated by a cryptographically secure random number generator — not a hand-typed phrase or a simple word. Strong random keys are the single most impactful factor in robust protection, regardless of which algorithm you choose. A password-based AES workflow should use a proper password derivation function with a random value to stretch the passphrase into a full-entropy private key.
Hash passwords — don't encrypt them. For user password protection, use one-way hashing via bcrypt or Argon2 — never reversible encryption. Digest hashing produces a fixed-length fingerprint that cannot be reversed; password digest functions with a slow algorithm make brute-force cracking computationally expensive. Store only the hash; use a secure credential store or dedicated vault for secrets you need to retrieve. Password encryption is the wrong tool for credentials — irreversible digest generation is the right one. Encryption is reversible: given the key, you can always recover original text. A digest cannot be reversed — the distinction between transformation and digest matters enormously in password protection.
Manage keys securely. Never hardcode keys in source code or store them alongside your protected data. In production, use a KMS (Key Management Service), an HSM (Hardware Security Module), AWS Secrets Manager, HashiCorp Vault, or another dedicated credential store. Implement key rotation on a regular schedule and enforce strict access controls on who can retrieve production secrets. Good key administration is what separates a theoretically sound encryption scheme from one that is practical and secure.
Encrypt data in transit with TLS. Encryption at rest protects stored data, but you must also encrypt data in transit using TLS to protect internet traffic and network communications. Without it, an attacker can intercept messages in their unprotected form before they ever reach storage. Secure transport protocols form the foundation of web security, email security, and secure communication across all digital communication channels. Use them for every payload, including when you share protected text or store protected values in transit to cloud storage.
Keep libraries updated. Encryption libraries receive patches as new weaknesses are discovered. Continuous updates and regular audit implementation reviews ensure your encryption methods remain hardened against the latest cryptographic attacks. Pinning to an old library version can expose you to known flaws that have long since been fixed upstream. Follow industry security standards and check OWASP guidance regularly.

Encryption is not encoding. Data representation techniques — such as Base64 encoding or base64 encode — change how data is formatted to make it transmission-safe, but they offer zero confidentiality protection: anyone can reverse them instantly with a decoding step. Confusing transformation with protection is a common mistake. Similarly, transformation and digest generation are entirely different operations. Encryption uses a key to protect sensitive data; representation formats use a public, reversible modular conversion; digest functions are irreversible. If you only need a transmission-safe format without confidentiality, use a base64 encode or format-conversion tool instead — need Base64 instead? It's the right tool for translations and format conversion without a protection requirement. For true confidentiality and data protection, always encrypt. This browser-side tool exists for the latter purpose.

Frequently Asked Questions

What format is the encrypted output?: A single Base64 string containing the random salt (16 bytes), the random IV/nonce (12 bytes), and the AES-256-GCM ciphertext (which includes its own authentication tag) concatenated together -- self-contained, so you only need to copy one value to decrypt later, with no separate salt or IV to track.
Why does decryption need the exact same passphrase?: The passphrase is run through PBKDF2 (250,000 iterations, SHA-256) together with the salt stored in the encrypted output to derive the actual AES-256 key -- get the passphrase even slightly wrong and the derived key is completely different, so decryption fails outright rather than producing garbled text (GCM's built-in authentication tag catches this and reports a clear error instead).
Why 250,000 PBKDF2 iterations?: It's a deliberate slowdown that makes brute-forcing a weak passphrase significantly more expensive for an attacker, while still completing in a fraction of a second for a legitimate user with the correct passphrase -- roughly in line with current OWASP recommendations for PBKDF2-SHA256.
Is this the same as a password manager's encryption?: It uses the same well-established building blocks (AES-256-GCM, PBKDF2) that many password managers rely on, but this tool is a simple one-off encrypt/decrypt utility, not a full vault -- there's no key storage, no session, no sync. Use it for sharing a short secret text securely, not as a replacement for dedicated encrypted storage.
Is my text or passphrase sent anywhere?: No. Both encryption and decryption happen entirely in your browser using the Web Crypto API -- nothing is transmitted, logged, or stored. Reload the page and everything is gone.