k6/encoding

Encoding utilities for base64 encoding and decoding

The k6/encoding module provides base64 encoding and decoding functionality as defined by RFC4648.

Import

import encoding from 'k6/encoding';

Functions

b64encode()

Encodes data in base64 format.

input · string | ArrayBuffer · required

The input string or ArrayBuffer object to base64 encode.

encoding · string · default: "std"

The base64 encoding to use:

• "std" - Standard encoding with = padding and +// characters (default)
• "rawstd" - Standard encoding without = padding
• "url" - URL-safe encoding with -/_ instead of +//
• "rawurl" - URL-safe encoding without = padding

return · string

The base64 encoding of the input data.

String encoding

import { check } from 'k6';
import encoding from 'k6/encoding';

export default function () {
  const str = 'hello world';
  const enc = 'aGVsbG8gd29ybGQ=';
  check(null, {
    'is encoding string correct': () => encoding.b64encode(str) === enc,
  });
}

import { check } from 'k6';
import encoding from 'k6/encoding';

export default function () {
  const buf = new Uint8Array([104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]).buffer;
  const enc = 'aGVsbG8gd29ybGQ=';
  check(null, {
    'is encoding ArrayBuffer correct': () => encoding.b64encode(buf) === enc,
  });
}

import encoding from 'k6/encoding';

export default function () {
  const str = 'hello world!';
  const urlSafe = encoding.b64encode(str, 'url');
  console.log(urlSafe); // aGVsbG8gd29ybGQh
}

---

b64decode()

Decodes a base64 encoded string into the original unencoded input.

input · string · required

The string to base64 decode.

encoding · string · default: "std"

The base64 encoding to use:

• "std" - Standard encoding with = padding and +// characters (default)
• "rawstd" - Standard encoding without = padding
• "url" - URL-safe encoding with -/_ instead of +//
• "rawurl" - URL-safe encoding without = padding

format · string

Output format:

• "s" - Return as string
• Unspecified - Return as ArrayBuffer (default)

return · ArrayBuffer | string

The base64 decoded version of the input in either string or ArrayBuffer format.

Decode to string

import { check } from 'k6';
import encoding from 'k6/encoding';

export default function () {
  const str = 'hello world';
  const enc = 'aGVsbG8gd29ybGQ=';
  check(null, {
    'is decoding to string correct': () => encoding.b64decode(enc, 'std', 's') === str,
  });
}

import { check } from 'k6';
import encoding from 'k6/encoding';

export default function () {
  const enc = 'aGVsbG8gd29ybGQ=';
  const expBin = new Uint8Array([104, 101, 108, 108, 111, 32, 119, 111, 114, 108, 100]);
  
  check(null, {
    'is decoding to ArrayBuffer correct': () => {
      const decBin = new Uint8Array(encoding.b64decode(enc));
      if (decBin.length != expBin.length) return false;
      for (let i = 0; i < decBin.length; i++) {
        if (decBin[i] !== expBin[i]) return false;
      }
      return true;
    },
  });
}

import encoding from 'k6/encoding';

export default function () {
  const urlEncoded = 'aGVsbG8gd29ybGQh';
  const decoded = encoding.b64decode(urlEncoded, 'url', 's');
  console.log(decoded); // hello world!
}

Encoding Types

Standard (std)

Default base64 encoding with = padding characters and +// in the alphabet.

Raw Standard (rawstd)

Standard encoding without = padding characters.

URL-safe (url)

URL-safe encoding using - and _ instead of + and /, with padding.

Raw URL-safe (rawurl)

URL-safe encoding without = padding characters.

Use Cases

• Encoding binary data for HTTP headers or URLs
• Encoding authentication credentials (Basic Auth)
• Working with Base64-encoded API payloads
• Converting between binary and text representations
• Handling file uploads as base64 strings

Use URL-safe encoding (url or rawurl) when the encoded data will be used in URLs or filenames to avoid special characters.