Base64 in Java

How to encode and decode Base64 in Java — with copy-paste examples and a live converter to check your output.

Since Java 8, java.util.Base64 provides standard, URL-safe and MIME encoders/decoders. Always pass an explicit charset when converting between String and byte[].

Encode to Base64 in Java

Java

import java.util.Base64;
import java.nio.charset.StandardCharsets;

String encoded = Base64.getEncoder()
    .encodeToString("Hello, World!".getBytes(StandardCharsets.UTF_8));

Decode Base64 in Java

Java

import java.util.Base64;
import java.nio.charset.StandardCharsets;

byte[] decoded = Base64.getDecoder().decode(encoded);
String text = new String(decoded, StandardCharsets.UTF_8);

Notes & gotchas

Use Base64.getUrlEncoder() for URL-safe output and Base64.getMimeEncoder() for MIME line-wrapped output. Specifying StandardCharsets.UTF_8 avoids platform-dependent encoding bugs.

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Base64 in other languages

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Base64 in Java — FAQ

How do I Base64 encode a string in Java?+

Use the code shown above. Use Base64.getUrlEncoder() for URL-safe output and Base64.getMimeEncoder() for MIME line-wrapped output. Specifying StandardCharsets.UTF_8 avoids platform-dependent encoding bugs.

How do I decode Base64 back to text in Java?+

Use the decode snippet above. Base64 decoding is lossless, so you get the exact original bytes back; decode them with UTF-8 to recover text.

Is Base64 encoding the same across programming languages?+

Yes. Base64 is a standard (RFC 4648), so a string encoded in one language decodes correctly in any other. Only the API differs, not the output.

Does Base64 secure my data?+

No. Base64 is an encoding, not encryption — anyone can decode it. Never use it to protect secrets.