Convert from Instagram Shortcode to Id and Back using big-integer

InstagramIdConvert.js

var bigint = require( 'big-integer' )

var lower = 'abcdefghijklmnopqrstuvwxyz';
var upper = lower.toUpperCase();
var numbers = '0123456789'
var ig_alphabet =  upper + lower + numbers + '-_'
var bigint_alphabet = numbers + lower

function toShortcode( longid )
{
	var o = bigint( longid ).toString( 64 )
	return o.replace(/<(\d+)>|(\w)/g, (m,m1,m2) =>
	{
		return ig_alphabet.charAt( ( m1 )
		  ? parseInt( m1 ) 
		  : bigint_alphabet.indexOf( m2 ) )
	});
}

function fromShortcode( shortcode )
{
	var o = shortcode.replace( /\S/g, m =>
	{
		var c = ig_alphabet.indexOf( m )
		var b = bigint_alphabet.charAt( c ) 
		return ( b != "" ) ? b : `<${c}>`
	} )	
	return bigint( o, 64 ).toString( 10 )
}

toShortcode(  '908540701891980503' ) // s.b. 'ybyPRoQWzX'
fromShortcode( 'ybyPRoQWzX' ) // s.b. '908540701891980503'

Same here. Spent 2 days trying to fix this basic conversion which FB could do it for us. It makes total sense.

For anyone comes across this... this short code converter only works to generate the ig_id, but the facebook graph api ids are different and this doesn't work for thate

Examples shown above:
17889455560051444
17883949432067035

These are both ids from the ig graph api

In Python if anyone is interested!

>>> id_to_shortcode = lambda instagram_id: base64.b64encode(instagram_id.to_bytes(9, 'big'), b'-_').decode().replace('A', ' ').lstrip().replace(' ', 'A')
>>> def shortcode_to_id(shortcode):
...     code = ('A' * (12-len(shortcode)))+shortcode
...     return int.from_bytes(base64.b64decode(code.encode(), b'-_'), 'big')

Thanks for sharing the code for the python functions. It was very helpful to me. I organized them for better understanding:

import base64


def shortcode_to_id(shortcode: str) -> int:
    code = ('A' * (12-len(shortcode)))+shortcode
    return int.from_bytes(base64.b64decode(code.encode(), b'-_'), 'big')


def id_to_shortcode(pk: int) -> str:
    bytes_str = base64.b64encode(pk.to_bytes(9, 'big'), b'-_')
    return bytes_str.decode().replace('A', ' ').lstrip().replace(' ', 'A')


print(id_to_shortcode(3549837394260045367))
print(shortcode_to_id("DFDjk1fRK43"))

hii anyone found how to get asset id from shortcodes ?

it's not possible.

Here is a simpler way to do the decode part using built-in BigInt and Base64URL handling. This is typescript but you can easily remove the types if you want.

function instagramShortCodeToId(shortCode: string) {
  const paddedShortCode = shortCode.padStart(12, 'A');
  //const bytes = Buffer.from(paddedShortCode, 'base64url'); // if you want to use Node
  const bytes = Uint8Array.fromBase64(paddedShortCode, { alphabet: 'base64url' });

  let id = 0n; // this is a BigInt
  for (let i = 0; i < bytes.length; i++) {
    // shift by one byte and add next byte
    id = (id << 8n) + BigInt(bytes[i]);
  }

  return id;
}

and a bonus of extracting the timestamp in milliseconds

function instagramIdToTimestampMs(id: bigint) {
  const instagramEpochMs = 1314220021721n;

  const offsetTimestamp = id >> (64n - 41n);
  const timestampMs = offsetTimestamp + instagramEpochMs;

  return Number(timestampMs);
}

function instagramShortCodeToTimestampMs(shortCode: string) {
  return instagramIdToTimestampMs(instagramShortCodeToId(shortCode));
}

implementing the encode should be pretty straightforward using the same approach.