I am interested in generating a bitcoin address with the shortest possible FirstBits. By random trial and error I found that 1ijj1 is untaken. Is there a way to find the shortest possible untaken FirstBits? (So I can generate it using vanitygen)

  • If I was an evil person I'd generate 1ijj1 it myself just for the lulz.
    – o0'.
    Commented Feb 5, 2013 at 15:59
  • According to this post all of the 4 character firstbits are taken.
    – Nick ODell
    Commented Feb 6, 2013 at 1:31

1 Answer 1


Yes there is a solution, it is brute-force. Make a loop and add variable characters, test them one by one. Start with one variable characters, try all combinations, add another variable character, try all combinations, rinse, repeat until you find unused firstbits.

  • Okay... But how do I check if a given firstbits is used?
    – lurf jurv
    Commented Feb 5, 2013 at 22:46
  • If I wanted to do it I'd plug into the blockchain API somehow and script the search. If you're going to do a brute-force search you'll have to script it anyway.
    – David
    Commented Feb 5, 2013 at 23:42
  • @David, that seems rather hard on the firstbits website, given that you'd need 5 million requests (ish) to fully search for 5 character firstbits.
    – Nick ODell
    Commented Feb 6, 2013 at 1:30
  • 1
    Hmm. Is there some kind of database I can download of firstbits that I can search through?
    – lurf jurv
    Commented Feb 6, 2013 at 3:26
  • @lurfjurv Download, probably not. However, you can use a program called Abe to make a firstbit database. I wrote a guide about setting up Abe back in November, which I just updated to cover the firstbits feature.
    – Nick ODell
    Commented Feb 6, 2013 at 4:23

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