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Hash Generator & Encoder — SHA-256, MD5, Base64, JWT Decoder

Generate cryptographic hashes, encode and decode Base64, URL, and HTML entities, and decode JWT tokens. All processing happens locally in your browser. No data is ever sent to a server.

All processing happens in your browser. No data is sent to any server.
Output Format:

How It Works

1

Choose Your Tool

Select from Hash Generator, Base64, URL Encode, HTML Entity, or JWT Decoder tabs. Each tool is specialized for its encoding type.

2

Enter Your Data

Type or paste text into the input field. For hashing, you can also upload a file. Results are generated instantly as you type.

3

Copy Results

Copy individual results or all hashes at once. Everything runs in your browser with zero server communication.

Why Use Our Hash & Encoder Tool?

100% Private

All hashing and encoding runs entirely in your browser using native Web Crypto APIs. Your data never leaves your device -- nothing is sent to any server.

5 Tools in One

Hash Generator (MD5, SHA-1/256/384/512), Base64, URL Encoding, HTML Entity encoding, and JWT Decoder in a single unified interface.

File Hashing Support

Hash files of any size directly in the browser using the Web Crypto API. Verify file integrity with SHA-256 or SHA-512 checksums.

Understanding Cryptographic Hash Functions

A cryptographic hash function takes any input and produces a fixed-size output (the hash or digest) that is unique to that input. Even a single character change in the input produces a completely different hash. This property, called the avalanche effect, makes hash functions essential for data integrity verification, digital signatures, and password storage.

Our free hash generator supports five algorithms: MD5 (128-bit), SHA-1 (160-bit), SHA-256 (256-bit), SHA-384 (384-bit), and SHA-512 (512-bit). All SHA hashes are computed using the browser's native crypto.subtle API for maximum performance and security.

When to Use Each Hash Algorithm

  • MD5 -- Fast but cryptographically broken. Use only for non-security checksums (file deduplication, cache keys). Never use for passwords or security.
  • SHA-1 -- Deprecated for security purposes since 2017. Collisions have been demonstrated (SHAttered attack). Use only for legacy compatibility.
  • SHA-256 -- The most widely used secure hash. Used in SSL/TLS certificates, Bitcoin, Git commits, and code signing. Recommended for most applications.
  • SHA-384 -- Truncated version of SHA-512. Used in some TLS cipher suites and government standards (FIPS 180-4).
  • SHA-512 -- Strongest hash in the SHA-2 family. Preferred for maximum security and slightly faster than SHA-256 on 64-bit processors.

Base64 Encoding Explained

Base64 is a binary-to-text encoding scheme that represents binary data using 64 printable ASCII characters. Every 3 bytes of input become 4 Base64 characters, making the output approximately 33% larger than the input. Common use cases include:

  • Data URIs -- Embedding images directly in HTML or CSS without separate HTTP requests.
  • Email attachments -- MIME encoding uses Base64 to transmit binary files over text-based email protocols.
  • API payloads -- Sending binary data (images, files) within JSON or XML API requests.
  • JWT tokens -- Both the header and payload of a JWT are Base64URL-encoded.

URL Encoding Best Practices

URL encoding ensures special characters are safely transmitted in URLs. The key rules are:

  • Reserved characters (: / ? # [ ] @ ! $ & ' ( ) * + , ; =) have special meaning in URLs and must be encoded when used as data.
  • Unsafe characters (spaces, <, >, {'{'}, {'}'}, |, \, ^, ~) should always be encoded.
  • Unreserved characters (A-Z, a-z, 0-9, -, _, ., ~) never need encoding.
  • Use encodeURIComponent() for individual query parameter values. Use encodeURI() for complete URLs where you want to preserve the URL structure.

JWT Token Structure and Security

A JSON Web Token consists of three Base64URL-encoded parts separated by dots: xxxxx.yyyyy.zzzzz. The Header specifies the signing algorithm (e.g., HS256, RS256). The Payload contains claims -- standard claims like exp (expiration), iat (issued at), sub (subject), and custom claims like user roles or permissions. The Signature is created by hashing the header and payload with a secret key.

Important: JWTs are not encrypted by default. The payload is only Base64-encoded, meaning anyone can read it. Never store sensitive data (passwords, credit card numbers) in JWT payloads. Use JWE (JSON Web Encryption) if payload confidentiality is required.

Frequently Asked Questions

What is a hash function and what is it used for?
A hash function converts any input into a fixed-length string that cannot be reversed back to the original data. They are used for data integrity verification (checksums), password storage, digital signatures, and deduplication. Common hash algorithms include MD5, SHA-1, SHA-256, SHA-384, and SHA-512.
What is the difference between SHA-256 and MD5?
SHA-256 is cryptographically secure while MD5 is broken and vulnerable to collision attacks. MD5 produces a 128-bit (32-character hex) hash, while SHA-256 produces a 256-bit (64-character hex) hash from the SHA-2 family. For any security-sensitive application (password hashing, certificate validation, data integrity), use SHA-256 or SHA-512 instead of MD5.
What is Base64 encoding and when should I use it?
Base64 converts binary data into printable ASCII text, commonly used for embedding images and transmitting files. It uses 64 characters (A-Z, a-z, 0-9, +, /) and is widely used in data URIs, JSON/XML payloads, email attachments (MIME), and text-based databases. Base64 is NOT encryption -- it is easily reversible and should never be used for security.
How does URL encoding work?
URL encoding replaces unsafe characters with a percent sign followed by two hex digits, like %20 for spaces. This ensures URLs are transmitted correctly, since certain characters have special meaning in URLs (?, &, =, #). Use encodeURIComponent() for query parameter values and encodeURI() for full URLs.
What is a JWT and how do I read one?
A JWT (JSON Web Token) is a compact, dot-separated token used for authentication and data exchange. It has three parts: Header (algorithm and token type), Payload (claims like user ID, expiration), and Signature (verification hash). Our decoder shows the Header and Payload as formatted JSON and indicates whether the token has expired based on the exp claim.
Is it safe to decode JWTs in the browser?
Yes, decoding JWTs in the browser is safe because it only reads Base64-encoded data, not encrypted secrets. The Signature part requires a secret key to verify but not to decode. Our tool never sends your token to any server. However, be cautious about pasting production tokens containing sensitive data in any online tool that does transmit data.
What are HTML entities and why do they matter?
HTML entities are special codes that safely represent reserved characters like < and & in web pages. For example, < becomes &lt; and & becomes &amp;. Encoding user input as HTML entities prevents Cross-Site Scripting (XSS) attacks by ensuring that HTML tags in user-submitted content are displayed as text rather than executed as code.
Can I hash files with this tool?
Yes, you can hash any file directly in your browser using SHA-1, SHA-256, SHA-384, and SHA-512. The file is read entirely in your browser via the Web Crypto API and never uploaded to a server. Note: MD5 is only available for text input since it uses a JavaScript implementation rather than Web Crypto.

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Last updated: 2025-03-17 · Built & maintained by the Aibrify team — trusted by 10,000+ marketers

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