Encode and Decode Base64 Online
Base64 encoding converts binary data into a safe ASCII string. It's used in data URIs, JWT tokens, email attachments, and APIs that transport binary data over text channels.
Common Base64 use cases
- Embed images in CSS as data URIs (background: url('data:image/...'))
- Inspect JWT token segments (header and payload are Base64url encoded)
- Encode API credentials in HTTP Basic Auth headers
- Decode email attachment content
- Pass binary data in JSON payloads
Base64 vs Base64url
Standard Base64 uses +, /, and = characters. Base64url (used in JWTs and URLs) replaces + with - and / with _, and omits padding =. Irreva's tool handles both variants.
Frequently Asked Questions
Does Base64 encrypt data?
No — Base64 is encoding, not encryption. Anyone can decode a Base64 string instantly. Don't use it to hide sensitive data.
Why does Base64 output look longer than the input?
Base64 expands data by ~33% — three bytes of input produce four characters of output.