base62.js

function toBaseN(num, base) {
  if (num === 0) {
    return '0';
  }
  var digits = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
  var len = Math.min(digits.length, base);
  var result = ''; 
  while (num > 0) {
    result = digits[num % len] + result;
    num = parseInt(num / len, 10);
  }
  
  return result;
}

function fromBaseN(str, base) {
  if (str === null || str.length === 0) {
    return 0;
  }
  var digits = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
  var len = Math.min(digits.length, base);
  var result = 0;
  for (var i=0 ; i<str.length ; i++) {
    var p = digits.indexOf(str[i]);
    if (p < 0 || p >= base) {
      return NaN;
    }
    result += p * Math.pow(digits.length, str.length - i - 1);
  }
  return result;
}

function toBase62(n) {
  if (n === 0) {
    return '0';
  }
  var digits = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
  var result = ''; 
  while (n > 0) {
    result = digits[n % digits.length] + result;
    n = parseInt(n / digits.length, 10);
  }
  
  return result;
}

function fromBase62(s) {
  var digits = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
  var result = 0;
  for (var i=0 ; i<s.length ; i++) {
    var p = digits.indexOf(s[i]);
    if (p < 0) {
      return NaN;
    }
    result += p * Math.pow(digits.length, s.length - i - 1);
  }
  return result;
}

base62.php

if (!function_exists('base62_encode')) {
    /**
     * Convert a 10 base numeric string to a 62 base string
     *
     * @param  int $value
     * @return string
     */
    function base62_encode($value)
    {
        return to_base($value, 62);
    }
}

if (!function_exists('base62_decode')) {
    /**
     * Convert a string from base 62 to base 10 numeric string
     *
     * @param  string $value
     * @return int
     */
    function base62_decode($value)
    {
        return to_base10($value, 62);
    }
}

if (!function_exists('to_base')) {

    /**
     * Convert a numeric string from base 10 to another base.
     *
     * @param $value  decimal string
     * @param int $b base , max is 62
     * @return string
     */
    function to_base($value, $b = 62)
    {
        $base = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $r = $value % $b;
        $result = $base[$r];
        $q = floor($value / $b);

        while ($q) {
            $r = $q % $b;
            $q = floor($q / $b);
            $result = $base[$r] . $result;
        }

        return $result;
    }
}

if (!function_exists('to_base10')) {
    /**
     * Convert a string from a given base to base 10.
     *
     * @param  string $value string from given base
     * @param  int $b base, max is 62
     * @return string
     */
    function to_base10($value, $b = 62)
    {
        $base = '0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ';
        $limit = strlen($value);
        $result = strpos($base, $value[0]);

        for ($i = 1; $i < $limit; $i++) {
            $result = $b * $result + strpos($base, $value[$i]);
        }

        return $result;
    }
}

base62.py

#!/usr/bin/python
# -*- coding=UTF-8 -*-

from __future__ import print_function, division

BASE62 = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"

def encode(num, alphabet=BASE62):
    """Encode a positive number in Base X

    Arguments:
    - `num`: The number to encode
    - `alphabet`: The alphabet to use for encoding
    """
    if num == 0:
        return alphabet[0]
    arr = []
    base = len(alphabet)
    while num:
        num, rem = divmod(num, base)
        arr.append(alphabet[rem])
    arr.reverse()
    return ''.join(arr)

def decode(string, alphabet=BASE62):
    """Decode a Base X encoded string into the number

    Arguments:
    - `string`: The encoded string
    - `alphabet`: The alphabet to use for encoding
    """
    base = len(alphabet)
    strlen = len(string)
    num = 0

    idx = 0
    for char in string:
        power = (strlen - (idx + 1))
        num += alphabet.index(char) * (base ** power)
        idx += 1

    return num

if __name__ == '__main__':
    print(encode(123004569870))
    print(decode('2agqDFK'))