Free Online Security & Crypto Tools
Encrypt, decrypt, hash, sign, and verify data directly in your browser. All tools use the Web Crypto API and process data 100% client-side.
Why Use Browser-Based Security Tools?
Security and cryptography tools handle some of the most sensitive data you work with: API tokens, private keys, passwords, encrypted messages, and security headers. Using online tools that upload your data to remote servers introduces unnecessary risk. Every security tool on ThisDevTool runs entirely in your browser using the Web Crypto API, which is a built-in browser feature that provides hardware-accelerated cryptographic primitives. Your keys, tokens, and sensitive data never leave your device.
Encryption and Decryption
The AES Encryption tool uses AES-256-GCM with PBKDF2 key derivation to encrypt and decrypt text with a password. This is the same encryption standard used by governments and financial institutions. The RSA Key Generator creates 2048-bit or 4096-bit RSA key pairs and exports them in PEM format, which you can use for SSH, TLS, and code signing.
Hashing and Integrity Verification
The Hash Generator computes SHA-256, SHA-384, SHA-512, and SHA-1 digests of any text input using the Web Crypto API. The HMAC Generator creates keyed-hash message authentication codes for verifying both data integrity and authenticity. The File Checksum Verifier calculates and compares file hashes to confirm download integrity, detecting corruption or tampering.
JWT (JSON Web Token) Tools
JSON Web Tokens are the standard for API authentication and single sign-on. The JWT Decoder splits tokens into their header, payload, and signature components, displaying claims like expiration, issued-at, and custom fields. The JWT Builder constructs tokens with custom claims and header options, useful for testing API authentication flows during development.
Security Headers
Properly configured HTTP security headers are essential for protecting your web applications. The CSP Generator builds Content Security Policy headers with a form-based interface, directive explanations, and a strictness rating that helps you balance security with compatibility. The CORS Header Builder generates Cross-Origin Resource Sharing configurations with code snippets for Express, Nginx, Apache, and Flask. The SRI Hash Generator creates Subresource Integrity hashes for CDN scripts and stylesheets.
Certificate and Authentication Tools
The SSL Certificate Decoder parses PEM-encoded X.509 certificates and displays the subject, issuer, validity dates, and extensions. The TOTP Generator creates time-based one-time passwords compatible with Google Authenticator and other 2FA apps. The PBKDF2 Password Hasher generates and verifies password hashes with configurable iterations for secure password storage testing.
Classical Ciphers
For educational purposes and CTF challenges, we also offer classical cipher tools including the Caesar Cipher with brute force and frequency analysis, and the ROT13 Cipher with ROT5, ROT47, and custom rotation variants. These tools are excellent for learning the fundamentals of cryptography and for solving encoding puzzles.
Frequently Asked Questions
Is it safe to use online encryption tools?
It depends on the tool. ThisDevTool's security tools run 100% in your browser using the Web Crypto API — a built-in browser feature that provides cryptographic primitives. Your data never leaves your device. There are no server requests, no logging, and no data storage. You can verify this by inspecting the page source or monitoring network activity in your browser's developer tools.
What is the difference between hashing and encryption?
Hashing is a one-way function that converts input into a fixed-length digest (e.g., SHA-256 produces a 256-bit hash). You cannot reverse a hash to get the original input. Encryption is a two-way process that transforms data using a key, and the original data can be recovered with the correct key. Use hashing for password storage and data integrity checks. Use encryption when you need to securely transmit and later decrypt data.
What is a JWT and how do I decode it?
A JWT (JSON Web Token) is a compact, URL-safe token format used for authentication and authorization. It consists of three Base64-encoded parts: a header (algorithm and type), a payload (claims like user ID and expiration), and a signature. Our JWT Decoder splits the token and displays the header and payload as formatted JSON, along with the expiration time and other metadata.
What is a Content Security Policy (CSP)?
A Content Security Policy is an HTTP response header that controls which resources (scripts, styles, images, fonts, frames) a browser is allowed to load on your page. CSP prevents cross-site scripting (XSS), clickjacking, and data injection attacks by whitelisting trusted sources. Our CSP Generator provides a form-based builder with directive explanations and a strictness rating.
How do CORS headers work?
CORS (Cross-Origin Resource Sharing) headers control which external domains can make requests to your API. The key headers are Access-Control-Allow-Origin (which domains), Access-Control-Allow-Methods (which HTTP methods), and Access-Control-Allow-Headers (which request headers). Our CORS Header Builder generates these headers with code snippets for Express, Nginx, Apache, and Flask.