What is Base64? Encoding explained (with examples)

Base64 is an encoding that turns binary data (bytes) into text using a limited alphabet. It’s commonly used to embed images (data URIs), send binary safely in JSON, or move data through systems that expect text.

What Base64 is (and isn’t)

• Base64 is not encryption. Anyone can decode it.
• Base64 increases size by about 33%.
• Base64 is reversible—it’s meant for compatibility, not secrecy.

Common use cases

• Data URIs (small assets embedded directly in HTML/CSS)
• APIs that transport binary inside JSON payloads
• Emails and MIME attachments
• JWTs use a URL-safe Base64 variant (Base64url)

Standard Base64 vs Base64url

Base64url is a URL-safe variant used by JWTs. It swaps characters like + and / for - and _ to avoid URL escaping.

Read the full breakdown: Base64url vs Base64 .

Examples

Encode plain text

Input:  hello
Output: aGVsbG8=

Decode a Base64 string

Input:  eyJmb28iOiJiYXIifQ==
    Output: {"foo":"bar"}

Try it instantly

Use the tool page to encode/decode text, images, JSON, and files: Base64 Encoder & Decoder .

Related

• Base64url vs Base64 (JWT-friendly encoding)
• JWT Decoder (JWTs are Base64url encoded)
• JSON Formatter (format JSON before encoding)
• All tools