Byte Array Tools

Byte Array to Base64 Converter

Convert a byte array to Base64 or URL-safe Base64, and decode Base64 back to a byte array in decimal, hex or code form.

Switch between raw bytes and Base64 in either direction - useful when an API, a JWT or a config file carries binary data as text.

Byte Array → Base64 Base64 → Byte Array

Byte array

URL-safe Base64 (- and _, no = padding)

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Base64 makes data about a third larger - it is an encoding for transport, not compression or encryption.

What Is the Byte Array to Base64 Converter?

Base64 writes binary data using only letters, digits, + and /, so it can travel through JSON, email, URLs and config files. This tool converts a byte array to Base64 and Base64 back to a byte array, including the URL-safe variant used by JWTs and many web APIs.

When to Use It

An API expects a file or a key as Base64 and you have the raw bytes.
You received Base64 and need the bytes as an array for code or a test.
Checking a URL-safe Base64 value (with - and _) from a token.

How to Use It

Choose the direction: Byte Array → Base64 or Base64 → Byte Array.
Paste the input. Switching direction feeds the current result back in, so you can round-trip.
For encoding, tick URL-safe if needed; for decoding, choose the array format.

Example

The bytes 0x42, 0x79, 0x74, 0x65, 0x61, 0x72, 0x79, 0xFB, 0xFF encode to Qnl0ZWFyefv_ in URL-safe Base64 - the standard form would be Qnl0ZWFyefv/. Nine bytes make exactly twelve characters, so no = padding is needed.

Understanding the Output

Every 3 bytes become 4 Base64 characters, so Base64 is about 33% larger than the data. When the length is not a multiple of 3, standard Base64 adds one or two = signs; URL-safe Base64 usually drops them.

Limitations

Base64 is an encoding, not encryption - anyone can decode it. To encode or decode text rather than bytes, the Base64 Encoder / Decoder is simpler; for images, use Image to Base64.

Frequently Asked Questions

A Base64 variant that replaces + with - and / with _ so the value can be used in URLs and file names without escaping, and usually drops the = padding. JWTs and many web APIs use it. The decoder here accepts both variants.

Base64 turns every 3 bytes into 4 characters. When the data length is not a multiple of 3, the last group is padded with one or two = signs. Nine bytes need no padding; ten bytes need two = signs.

No. Base64 is a reversible encoding that anyone can decode without a key. It is used to carry binary data through text-only channels, not to hide it. Use proper encryption for secrets.

The Base64 Encoder / Decoder works with text. This tool works with raw bytes, so it can handle binary data that is not valid text, and it outputs byte arrays for code.