I was unable to find an answer through various searches online, so I figured an expert here might be able to help me...

Why is a tz address in lower case and a KT address in upper case?

Was there a technical reason or some kind of special naming convention chosen for this difference in letter case between these two addresses?

1 Answer 1


You can see in the commit 1c7d7ce7 that the prefix was previously "TZ1". The case was used to distinguish between the two types of adresses. This commit changed the letters to "limit confusion with tz1". Regarding the choice of the new letters, there is no official explanation as far as I can tell but, according to rumors, it may be a reference the first name of a very important member of the Tezos community.

  • To be clear, you mean to say that KT in uppercase was used instead of kt in lowercase because it was grandfathered from the former uppercase TZ1 format?
    – Svek
    Jul 20, 2019 at 3:59
  • 1
    Yes but that's an arbitrary choice. Lowercase was technically possible.
    – Clement J.
    Jul 20, 2019 at 5:57

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