I think it's just a renamed blk0001.dat file, but I can't find any references as to what it actually is other than a "binary blockchain" ....

  • As this has been marked as a duplicate, should I delete it or is there another way I can confirm that it is a duplicate?
    – Indolering
    Mar 16, 2014 at 22:36
  • The question is prominently marked as a duplicate and it has a valid answer, so it is fine to keep it. Some people might chose different terms to search for the same thing, so it is good to have several different question headers to point to the question. Also see: Why are some questions marked as duplicate?
    – Murch
    May 12, 2015 at 8:08

1 Answer 1


The bootstrap.dat file contains a serialized copy of the blockchain, usually up to the latest checkpoint released for the official client. The official bitcoin client will read this file when starting to create the blockchain without downloading it from the peer nodes. The file will then be renamed to bootstrap.dat.old so it won't be reprocessed when the client is restarted.

A Python script used to create the file can be found here. You will need an up-to-date pynode chain database.

If you have the Armory code, you can compile this C++ program. This uses the blockchain data blocks created by the official bitcoin client.

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