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Free Base64 Encoder & Decoder — Instant, Browser-Based

Encode text to Base64 or decode Base64 strings instantly. Supports Unicode. Runs in your browser — no data transmitted. ...

Input

Our Base64 encoder and decoder converts text to Base64 format or decodes Base64 strings back to plaintext — instantly in your browser using native JavaScript. Supports full Unicode through UTF-8 encoding. No data is transmitted to any server. Ideal for encoding data in APIs, embedding images in CSS, encoding email attachments, and preparing data for URL transmission.

What Is Base64 Encoding?

Base64 is a binary-to-text encoding scheme that converts binary data into an ASCII string format using 64 printable characters (A–Z, a–z, 0–9, +, /). It is used when binary data needs to be stored or transmitted in contexts that only support text. The name "Base64" refers to the 64 characters used in the encoding alphabet.

Base64 is not encryption — it is encoding. Anyone with the Base64 string can decode it back to the original. Use it for data portability, not data security. Encoded strings are approximately 33% larger than the original input.

Common Use Cases

API & JSON Data

Transmit binary data like images or files in JSON payloads where only text is supported. The Base64 string can be included as a JSON field value.

CSS Image Embedding

Embed small images directly in CSS as data URIs: background-image: url("data:image/png;base64,..."). Reduces HTTP requests for small icons.

Email Attachments

MIME email standard uses Base64 to encode attachments for transmission through text-only email protocols. Most email clients handle this automatically.

Authentication Headers

HTTP Basic Auth encodes credentials as Base64 in the Authorization header: Authorization: Basic [base64(username:password)].

JWT Token Payloads

JSON Web Tokens use Base64URL (a variant) to encode their header, payload, and signature segments. Decode a JWT here to inspect its contents.

Binary in URLs

Pass binary data through URLs by Base64-encoding it first. Use the URL-safe variant (replace + with - and / with _) for use in query parameters.

Frequently Asked Questions

Is Base64 the same as encryption?

No. Base64 is encoding, not encryption. Anyone with the Base64 string can decode it back to the original content trivially. Do not use Base64 to hide sensitive information. Use it for data portability — when you need to represent binary data as text.

Why is the Base64 output longer than the input?

Base64 encoding converts every 3 bytes of input into 4 Base64 characters. This means Base64-encoded data is approximately 33% larger than the original. The equals signs (=) at the end are padding to ensure the output length is a multiple of 4.

What is the difference between Base64 and Base64URL?

Standard Base64 uses + and / characters which have special meaning in URLs. Base64URL (used in JWTs and URL parameters) replaces + with - and / with _ to make the output URL-safe. This tool uses standard Base64.

Can Base64 encode any type of data?

Base64 can encode any binary data — text, images, files, audio. This tool accepts text input and encodes the UTF-8 representation. For encoding images or binary files, you would need a file-input version of the tool.