Input: any old Bitcoin address e.g.


Output: the FirstBits, in this case 1BCN1u

  • can you please tell where I can read about old and new bitcoin addresses? Oct 18, 2013 at 23:49
  • @SalvadorDali - I don't understand what you mean "old and new addresses"
    – ripper234
    Oct 19, 2013 at 14:31

2 Answers 2


Blockchain.info has APIs to generate and resolve firstbits.

Get firstbits,


Get address,




  • What is the purpose of this?
    – bvpx
    Oct 18, 2013 at 14:58
  • 1
    @bvpx: Https://en.bitcoin.it/wiki/Firstbits tells us that firstbits are basically a way for bitcoin users to type a few less key strokes (an address shortner for bitcoin addresses). However there are more than a few downsides to it. I hope the information is helpful.n Just start at the beginning and learn everything bitcoin wiki touches on. Feel reese to ask more questions. I always suggest using the search engine before posting so you keep good rep. You can always privately message me. But I am over on my altcoins pool mostly.
    – Joe White
    Oct 18, 2013 at 15:22
  • 2
    This service seems to be out of order currently.
    – akaihola
    Apr 22, 2014 at 5:25

Having seen that yes blockchain.info no longer offers this service I was able to find only one other Block explorer that do offer the FirstBit lookup on addresses:



Hope this helps :)


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