Base64 Encoder and Decoder

Encode text or images to Base64 and decode Base64 strings back — with instant image preview, fully client-side. Decoding access tokens? Try the JWT decoder for header and payload inspection.

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Reference

Base64 notes

What is Base64?

Base64 is a binary-to-text encoding scheme that represents bytes as ASCII characters. It is commonly used when binary data must be stored or transferred through text-only formats such as JSON, HTML, CSS, email, and environment variables.

How does the Base64 tool work?

The Base64 encoder converts UTF-8 text or image bytes into a Base64 string. The Base64 decoder reverses that process and can display image data URLs for preview. Base64 changes how data is represented; it does not compress, encrypt, or protect the original content.

When should you use Base64?

Encoding text values for JSON payloads and API tests
Decoding Base64 strings copied from logs, tokens, or configuration
Embedding small images as data URLs in HTML or CSS
Previewing Base64 image output before using it in a page
Working with MIME email attachments and text-safe binary data

What are the limitations of Base64?

Base64 is encoding, not encryption, and anyone can decode it
Encoded output is usually about 33% larger than the original bytes
Large Base64 images can increase HTML, CSS, or JSON file size quickly
Invalid padding or non-Base64 characters will cause decode errors
Base64 strings are not designed to be human readable

Base64 examples

encode Hello -> SGVsbG8=

encode Hello World! -> SGVsbG8gV29ybGQh

encode Pokémon are pocket monsters -> UG9rw6ltb24gYXJlIHBvY2tldCBtb25zdGVycw==

decode SGVsbG8= -> Hello

decode SGVsbG8gV29ybGQh -> Hello World!

decode UG9rw6ltb24gYXJlIHBvY2tldCBtb25zdGVycw== -> Pokémon are pocket monsters

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