Free Developer Tool — 100% Client-Side

Base64 Encoder / Decoder

Name: Base64 Encoder / Decoder - WebUtil
Author: WebUtil

Encode or decode text and files to and from Base64 format instantly.

Input

Output

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data in an ASCII string format. It is widely used for transmitting data over media that are designed to handle textual data. A Base64 encoder converts data into this format, while a Base64 decoder converts it back. Our free Base64 encoder online runs entirely in your browser for instant, private conversions.

Encode vs Decode

Encode

Converts text or binary data into a Base64 string. Useful for embedding data in HTML, CSS, or JSON, or for transmitting binary data through text-based protocols like HTTP.

Decode

Converts a Base64 string back to its original text or binary form. Useful for reading API payloads, decoding JWT tokens, or extracting embedded data from web pages.

Why Developers Use Base64

API Authentication — Basic Auth headers use Base64 encoded credentials.
Embedding Images — Convert images to Base64 data URIs for inline display in HTML or CSS.
JSON Payloads — Encode binary data as Base64 strings within JSON API payloads.
JWT Tokens — JSON Web Tokens use Base64url encoding for their header, payload, and signature.
Email Attachments — MIME encoding uses Base64 to transmit file attachments via email.

Common Use Cases

Base64 encoding is essential in modern web development. API developers use it daily for encoding request payloads, debugging authentication headers, and processing data from third-party services. Frontend developers use it to embed small images directly into CSS or HTML to reduce HTTP requests. Security professionals decode Base64 strings to inspect JWT tokens and API credentials during penetration testing.

How to Use This Base64 Tool

To encode text to Base64, type or paste your text into the input field and click Encode to Base64. To decode Base64 back to text, paste the encoded string and click Decode from Base64. The tool handles UTF-8 characters correctly, so emoji, non-Latin scripts, and special characters are all supported. Use the Copy button to copy the result to your clipboard.

Base64 Encoding Examples

Text → Base64

"Hello World" → SGVsbG8gV29ybGQ=

JSON → Base64

{"key": "value"} → eyJrZXkiOiAidmFsdWUifQ==

Base64 encoding, standardized under RFC 4648, is a binary-to-text encoding scheme that translates arbitrary binary data into a sequence of 64 printable ASCII characters (A-Z, a-z, 0-9, +, /). In modern web development, network protocols such as HTTP, MIME email, and JSON are designed to transmit textual data. When developers need to transmit binary payloads—such as images, PDF documents, cryptographic keys, or compiled WebAssembly modules—over text-only channels, Base64 ensures the data passes through firewalls, gateways, and mail servers without character corruption. Base64 works by dividing binary input into 6-bit chunks, each representing a value from 0 to 63 mapped to the standard Base64 index table, using '=' padding characters to ensure the total output length is a multiple of four. A critical engineering distinction to remember is that Base64 is an encoding format, NOT encryption: it provides zero confidentiality and can be decoded by anyone with access to the string. WebUtil's Base64 Encoder / Decoder processes both plain text and files directly in your browser using native JavaScript Uint8Array and the FileReader API, guaranteeing that private keys, credentials, and confidential files never leave your computer.

How to Do This in Code

const encoded = btoa('hello world');
const decoded = atob(encoded);

import base64
encoded = base64.b64encode(b'hello').decode()
decoded = base64.b64decode(encoded)

import "encoding/base64"

encoded := base64.StdEncoding.EncodeToString([]byte("hello"))
decoded, _ := base64.StdEncoding.DecodeString(encoded)

echo -n 'hello' | base64
echo 'aGVsbG8=' | base64 -d

Popular Developer Tools

JSON Formatter

Format, validate, and beautify JSON data

Base64 Encoder

Encode and decode Base64 instantly

JWT Decoder

Decode and inspect JWT tokens

Regex Tester

Test regular expressions in real-time

Hash Generator

Generate MD5, SHA-1, SHA-256 hashes

Deploy Your Next Project Fast

Get $200 free credit on DigitalOcean to deploy your apps with blazing-fast infrastructure.

Try DigitalOcean

Related Tools

JSON Formatter

Format, validate, and beautify your JSON data with syntax highlighting and error detection.

URL Encoder / Decoder

Encode or decode URLs and query parameters for proper web transmission.

HTML Entities Encoder

Convert special characters to HTML entities and vice versa for safe web rendering.

Related Guides & Tutorials

Encoders 5 min read

Base64 Encoding: Methods, Use Cases, and Best Practices

A deep dive into Base64 encoding, when to use it, common pitfalls, and how it works under the hood.

Base64 Encoder / Decoder FAQ

What is Base64 encoding and why is it used?

Base64 encoding translates binary data into 64 ASCII characters so it can be safely transmitted across text-based protocols like HTTP, JSON, XML, and email without character corruption.

Is Base64 considered encryption or secure?

No. Base64 is strictly an encoding mechanism, not encryption. Anyone who intercepts a Base64 string can decode it back to original data instantly. Never rely on Base64 for data security—always use AES or RSA encryption for sensitive data.

Why does Base64 increase data size by ~33%?

Base64 represents 3 bytes (24 bits) of binary data using 4 ASCII characters (32 bits). This mathematical ratio causes an unavoidable 33% increase in data transfer size.

What is the difference between standard Base64 and Base64URL?

Standard Base64 uses '+' and '/' characters, which have special syntactic meanings in URLs and file systems. Base64URL replaces '+' with '-' and '/' with '_', and often omits '=' padding to make tokens URL-safe.

How do Data URIs work with Base64 in HTML and CSS?

A Data URI allows small images and fonts to be inlined directly into HTML or CSS using the syntax: data:image/png;base64,iVBORw0KGgo... This eliminates an extra HTTP request at the expense of caching efficiency.