Base64 Encoder/Decoder - Free Online Base64 Tool

Plain Text

Base64

Features

100% Private

All encoding and decoding runs locally in your browser. Your data never leaves your device.

Instant Conversion

Encode or decode Base64 strings in milliseconds with zero server round-trips.

URL-Safe Mode

Generate URL-safe Base64 by replacing +, /, and = with URL-friendly characters.

Full UTF-8 Support

Correctly encodes and decodes multi-byte Unicode characters including emoji and CJK text.

One-Click Copy

Copy the encoded or decoded result to your clipboard with a single click.

No Installation

Works in any modern browser — no extensions, plugins, or accounts required.

How to Use

Enter Your Text or Base64 String

Paste plain text in the left panel to encode, or paste a Base64 string in the right panel to decode.

Choose Your Operation

Click "Encode" to convert text to Base64, "Decode" to convert Base64 back to text, or "URL-Safe Encode" for URL-compatible output.

Copy the Result

Click the "Copy" button to copy the result to your clipboard, ready to paste into your code, email, or API request.

Base64 vs Other Encoding Methods

Method	Character Set	Size Overhead	Best For
Base64 (Standard)	A-Z, a-z, 0-9, +, /	~33%	Email attachments, data URIs, JWT
Base64 (URL-Safe)	A-Z, a-z, 0-9, -, _	~33%	URL parameters, filenames
URL Encoding	%XX hex pairs	Up to 300%	URL query strings
Hex Encoding	0-9, A-F	100%	Hash digests, color codes
ASCII85	33-117 ASCII range	~25%	PDF internals, PostScript

Frequently Asked Questions

What is Base64 encoding?

Base64 is a binary-to-text encoding scheme that represents binary data using 64 ASCII characters (A-Z, a-z, 0-9, +, /). It is commonly used to embed binary data in text-based formats such as HTML, CSS, JSON, and email (MIME). Every 3 bytes of input produce 4 characters of output, resulting in roughly 33% size increase.

What is URL-safe Base64?

URL-safe Base64 replaces the standard + and / characters with - and _ respectively, and omits the trailing = padding. This variant is safe to use directly in URLs, query parameters, and filenames without additional percent-encoding. It is used in JWT tokens, OAuth signatures, and many web APIs.

Is Base64 encryption?

No. Base64 is an encoding scheme, not encryption. Anyone can decode Base64 without a key. It is designed for data transport, not security. If you need to protect sensitive data, use proper encryption algorithms like AES-256 before encoding.

Why does Base64 increase file size?

Base64 maps every 3 bytes of binary data to 4 ASCII characters, increasing data size by approximately 33%. This trade-off is necessary because many protocols (email, JSON, XML) only support text. For large files, consider using direct binary transfer instead.

Is my data secure when using this tool?

Yes. All encoding and decoding happens entirely in your browser using JavaScript's built-in btoa() and atob() functions. No data is transmitted to any server. Your text never leaves your device.

What are common use cases for Base64?

Base64 is widely used for embedding images as data URIs in HTML/CSS, encoding email attachments (MIME), transmitting binary data in JSON APIs, storing credentials in HTTP Basic Authentication headers, and encoding JWT (JSON Web Token) payloads.

Related Tools

About Base64 Encoder / Decoder

Encode and decode Base64 online free with FreeToolBox — instantly convert text strings, URLs, and data to Base64 encoding and back. Base64 is a fundamental encoding scheme in web development, widely used across APIs, email systems (MIME), authentication protocols (HTTP Basic Auth, JWT), and data embedding (HTML data URIs, CSS background images). Every web developer encounters Base64 regularly, whether debugging API responses, embedding small assets inline, or handling file uploads in JSON payloads.

This tool runs entirely in your browser using JavaScript's native btoa() and atob() functions — no data is ever sent to a server. It supports standard Base64 (RFC 4648) and URL-safe Base64 (replacing + with - and / with _, stripping = padding) for safe use in URLs and filenames. Full UTF-8 Unicode support means you can encode emoji, Chinese characters, Arabic text, and any other multi-byte content correctly. Simply paste your text, click a button, and copy the result. Completely free, no account required, no rate limits.