Free Online Base64 Encoder & Decoder

Our Base64 tool lets you encode any plain text into Base64 format or decode Base64 strings back to readable text instantly. It fully supports UTF-8 characters including emojis, accented letters, and non-Latin scripts. Everything runs in your browser — your data never leaves your device.

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that represents binary data using a set of 64 printable ASCII characters: uppercase letters (A-Z), lowercase letters (a-z), digits (0-9), plus (+), and slash (/), with equals (=) used for padding. It was designed to safely transmit binary data through systems that only handle text.

The name "Base64" comes from the fact that it uses 64 different characters to represent data. Every 3 bytes of input data are converted into 4 Base64 characters, which means Base64-encoded data is approximately 33% larger than the original. This size increase is the tradeoff for universal text compatibility.

Common Uses for Base64

Email attachments — the MIME standard uses Base64 to encode binary file attachments so they can travel through email systems that were originally designed for plain text only.

Data URIs in HTML/CSS — small images, fonts, and files can be embedded directly into HTML or CSS using Base64-encoded data URIs, eliminating extra HTTP requests and improving page load performance for small assets.

API authentication — HTTP Basic Authentication encodes the username and password combination in Base64 before sending it in request headers. Note that Base64 is encoding, not encryption — it provides no security on its own.

Storing binary data in JSON/XML — since JSON and XML are text-based formats, binary data like images or files must be Base64-encoded before being included as string values.

JWT tokens — JSON Web Tokens use a URL-safe variant of Base64 (Base64URL) to encode the header and payload segments of the token.

Base64 vs Encryption

A critical distinction: Base64 is not encryption. It is a reversible encoding scheme with no secret key — anyone can decode Base64 data instantly. Never use Base64 alone to protect sensitive information like passwords, API keys, or personal data. For actual security, use proper encryption methods like AES-256 or TLS.

Frequently Asked Questions

Is Base64 encoding secure?

No. Base64 is encoding, not encryption. It is trivially reversible by anyone. It is designed for data transport compatibility, not security. Never rely on Base64 to hide or protect sensitive information.

Why is the Base64 output longer than the input?

Base64 converts every 3 bytes of input into 4 characters of output, resulting in approximately 33% size increase. This is inherent to the encoding scheme and cannot be avoided. The tradeoff is that the output is guaranteed to be safe ASCII text.

Does this tool support file encoding?

This tool encodes and decodes text. For encoding binary files (images, PDFs, etc.) to Base64, you would need a file-based encoder. The underlying principle is the same — the file's binary content is converted to a Base64 text string.

What characters are used in Base64?

Standard Base64 uses 64 characters: A-Z, a-z, 0-9, + (plus), and / (slash), with = (equals) for padding. The URL-safe variant replaces + with - (hyphen) and / with _ (underscore) to avoid issues in URLs.

Can Base64 handle Unicode and emojis?

Yes. Our tool first encodes the text as UTF-8 bytes, then applies Base64 encoding. This correctly handles all Unicode characters including emojis, accented letters, Chinese, Arabic, and other non-Latin scripts.