What is the difference between Base64 and Base64URL?

Standard Base64 uses + , / , and = padding, which are all reserved characters in URLs. Base64URL (RFC 4648 Section 5) replaces + with - and / with _ , and typically omits padding. This is the encoding used inside JWT tokens — each of the three JWT segments is Base64URL-encoded, not standard Base64.

Why do I see garbled text after decoding Base64?

The most common cause is a character encoding mismatch . Base64 encodes raw bytes, not text. If the original data was UTF-8 but your decoder assumes Latin-1 (or vice versa), accented characters and emoji will render incorrectly. Always ensure the encoding used at decode time matches the one used at encode time. Our tool defaults to UTF-8, which handles the vast majority of modern text correctly.

When should I use data URIs vs external files?

Data URIs ( data:image/png;base64,... ) inline binary content directly in HTML or CSS, saving an HTTP request. They are ideal for small assets under 2-4 KB — icons, simple SVGs, tiny sprites. Beyond that size, the 33% Base64 overhead plus the inability to cache the asset separately makes external files more efficient. Modern HTTP/2 multiplexing has also reduced the cost of extra requests.

What is HTML entity encoding and when do I need it?

HTML entity encoding converts characters that have special meaning in HTML into safe escape sequences: < for < , & for & , " for double quotes, etc. You need it whenever you inject user-generated content into HTML to prevent XSS (Cross-Site Scripting) attacks. Never trust raw user input — always encode before rendering. Validate the structure of your sanitized output with our HTML Validator .

How do I encode emoji and special characters in URLs?

Emoji and non-ASCII characters must first be encoded as UTF-8 bytes, then each byte is percent-encoded. For example, the emoji "smile" (U+1F600) becomes 4 bytes in UTF-8 and percent-encodes to %F0%9F%98%80 . In JavaScript, encodeURIComponent() handles this automatically. Test your encoded URLs with our URL Parser to confirm they decode correctly.

Base64 Encoder & Decoder

Free online encoder and decoder for Base64, URL encoding, HTML entities, and hexadecimal conversion

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Standard base64 encodingSupports UTF-8 and emoji

Encoding Guide

What is Base64 and When to Use It

Base64 is a binary-to-text encoding scheme that represents binary data using a 64-character ASCII alphabet (A-Z, a-z, 0-9, +, /). It works by taking every three bytes (24 bits) of input and splitting them into four 6-bit groups, each mapped to one of the 64 characters. When the input length is not a multiple of three, = padding characters are appended to signal the decoder how many bytes to discard.

This 33% size overhead is the cost of safe transport through text-only channels. Common use cases include:

Data URIs: Embedding small images directly in HTML or CSS (data:image/png;base64,...) eliminates an extra HTTP request, improving performance for icons and sprites under ~2 KB.
Email attachments (MIME): SMTP is a 7-bit protocol, so binary files must be Base64-encoded before being attached. The MIME standard (RFC 2045) mandates this encoding.
API payloads: When you need to transmit binary blobs inside JSON — which only supports text — Base64 is the standard approach. JWTs use a URL-safe variant called Base64URL that replaces +/ with -_ and omits padding.

URL Encoding Explained

URL encoding (also called percent-encoding) is defined in RFC 3986 and converts characters that are unsafe or reserved in a URI into a %XX hex representation. For example, a space becomes %20, an ampersand becomes %26, and a forward slash becomes %2F. This ensures that special characters do not break URL parsing.

In JavaScript, two functions handle URL encoding, and choosing the wrong one is a common bug:

encodeURI() encodes a full URI, leaving reserved delimiters like :, /, ?, #, and & intact. Use it when you have a complete URL and want to sanitize non-ASCII characters without breaking the structure.
encodeURIComponent() encodes everything except unreserved characters (A-Z a-z 0-9 - _ . ~). Use it for individual query parameter values, form data, or any fragment that will be embedded inside a larger URL.

A practical rule: if the string is a value going into a URL, use encodeURIComponent. If it is already a URL, use encodeURI. Test encoded URLs with our URL Parser to verify the result.

Encoding vs Encryption vs Hashing

These three concepts are frequently conflated, but they serve fundamentally different purposes. Understanding the distinction is critical for building secure systems.

Encoding (Base64, URL encoding, Hex) transforms data into a different representation for safe transport. It is fully reversible and uses no secret key. Anyone who sees the encoded output can decode it instantly. Encoding provides zero security — it is a format conversion, not a protection mechanism.
Encryption (AES, RSA, ChaCha20) transforms data into ciphertext using a secret key. Only someone with the correct key can decrypt and read the original data. Encryption is reversible by design, but only for authorized parties. Use encryption when data must be confidential in transit or at rest.
Hashing (SHA-256, BLAKE3) produces a fixed-size one-way digest. It cannot be reversed — there is no key that unlocks the original input. Hashing is used for integrity verification, fingerprinting, and password storage. Generate hashes with our Hash Generator.

A common anti-pattern is Base64-encoding a password or API key and treating it as "secure." It is not. If you need to protect sensitive data, use encryption. If you need to verify integrity without exposing data, use hashing. Encoding is only for format compatibility.

Frequently Asked Questions

Hash

MD5, SHA, BLAKE2/3

JSON

Validate, format & convert JSON

Base

Binary, Octal, Hex

URL

Parse & build URLs

URL Encoding Explained

In JavaScript, two functions handle URL encoding, and choosing the wrong one is a common bug:

encodeURI() encodes a full URI, leaving reserved delimiters like :, /, ?, #, and & intact. Use it when you have a complete URL and want to sanitize non-ASCII characters without breaking the structure.
encodeURIComponent() encodes everything except unreserved characters (A-Z a-z 0-9 - _ . ~). Use it for individual query parameter values, form data, or any fragment that will be embedded inside a larger URL.

A practical rule: if the string is a value going into a URL, use encodeURIComponent. If it is already a URL, use encodeURI. Test encoded URLs with our URL Parser to verify the result.

Base64 Encoder & Decoder

Encoding Guide

What is Base64 and When to Use It

URL Encoding Explained

Encoding vs Encryption vs Hashing

Frequently Asked Questions

What is the difference between Base64 and Base64URL?

Why do I see garbled text after decoding Base64?

When should I use data URIs vs external files?

What is HTML entity encoding and when do I need it?

How do I encode emoji and special characters in URLs?

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Hash

JSON

Base

URL

Encoding Guide

What is Base64 and When to Use It

URL Encoding Explained

Encoding vs Encryption vs Hashing

Frequently Asked Questions

What is the difference between Base64 and Base64URL?

Why do I see garbled text after decoding Base64?

When should I use data URIs vs external files?

What is HTML entity encoding and when do I need it?

How do I encode emoji and special characters in URLs?