Free Online Base64 Encoder Decoder

What is Base64 encoding?

Base64 is an encoding scheme that converts binary data into a sequence of ASCII characters. It's commonly used to embed images inline in HTML/CSS (data:image/png;base64,...), to encode credentials in HTTP Basic Auth, and to include binary data in JSON or Firebase RTDB.

The URL-safe variant replaces the + and / characters with - and _, making the string safe to use in a URL without additional encoding.

Is Base64 a form of encryption?

No. Base64 is just an encoding — anyone can decode it without keys. To actually encrypt data, use encryption tools like AES, or check out the HMAC-SHA256 page.

Why is Base64 longer than the original?

Base64 uses 6 bits per character instead of the standard 8, so every 3 original bytes become 4 Base64 characters — roughly a 33% size increase.

When to use a Base64 encoder

This tool encodes and decodes text or files to Base64, with support for URL-safe Base64 and image preview, processing everything locally in your browser.

When to use it

You need to convert a file (e.g. an image) into a Base64 string to embed in HTML, CSS or JSON.

You need to decode a Base64 string received from an API or another system to read its content.

You need the URL-safe variant of Base64 to use it in URL parameters without problematic characters.

When NOT to use it

You think Base64 protects or encrypts your data: it's just a reversible encoding with no key, not a security method. To protect data you need real encryption.

Alternatives

Our text cipher tool when the goal is to protect the content, not just represent it as text.

Native language functions (e.g. btoa/atob in JavaScript, base64 in Python) if you're already writing code and just need a one-off conversion.

Common mistakes

Treating Base64 as a security method: anyone can decode it instantly, with no key needed.

Forgetting the difference between standard and URL-safe Base64: the standard version uses characters (+ and /) that need encoding when placed in a URL, causing errors if not handled.

Encoding very large files as Base64 for transfer: it increases the payload size by roughly a third compared to the original binary file.

Frequently asked questions about Base64 encoding

No, Base64 is a reversible encoding with no key: anyone can decode it instantly. It should not be used to protect sensitive data, only to represent binary data as text.

The standard version uses the characters + and / which can cause problems if placed directly in a URL; the URL-safe version replaces these characters with - and _ so it can be used without extra encoding in URL parameters.

Yes, the tool also supports encoding files (with a preview for images), in addition to encoding/decoding plain text.

⚙️ Base64