I am trying to Decode the Raw hex data of a Coinbase Block to check my understanding of the DS but I am facing some difficulties in decoding marked by a ? below:

Q1. Can someone please check the existing understanding/interpratation and help explain and fill the gaps (marked by ?)

Q2. Is there a simple standalone program/library in to do the same? I have seen few parsers (though haven't used) but they require the complete blockchain .dat files that i cannot afford to download for this task.

The block is: https://www.blockchain.com/btc/block/485300


[PARAMETER]           [VALUE]

[Block Header]
version             - 00000020
Previous Block hash - 53f7ebc735f54ac8d4ebcc1eeb3d3bdea89603bdd27431000000000000000000
Merkel Root         - ff964ec70ea5a5356a04fdb044ca6c59ffda2dd6be02c63d9ea58fb6d46e0199
time                - 1a22bb59
bits                - 1801310B
nonce               - f6df26f8

01 - transaction count

[Tx List]
version                 - 01000000
<?>                     - 0001
input ct                - 01
prev tx                 - 0000000000000000000000000000000000000000000000000000000000000000
prev out n              - ffffffff
coinbase script length  - 31
coinbase script         - 03b46707244d696e656420627920416e74506f6f6c6b2f4542312f4144362f4e59412f332059bb221ab8080000615c0300
sequence                - ffffffff
Output count            - 02
value 1                 - 807c814a00000000
Script 1 length         - 19
Script 1                - 76a914660371326d3a2e064c278b20107a65dad847e8a988ac
value 2                 - 0000000000000000
Script 2 length         - 26
Script 2                - 6a24aa21a9ede2f61c3f71d1defd3fa999dfa36953755c690689799962b48bebd836974e8cf9
<?>                     - 0120
witness transaction id  - 000000000000000000000000000000000000000000000000000000000000000000000000
  • Q1 segregated witness aka segwit Also to be clear multibyte numbers are little-endian, and you've swapped bits to big-endian but not the others. Aug 25, 2021 at 3:50
  • @dave_thompson_085 thank you. updated the structure above for the seg_wit transaction id. just 4 bytes above unclear. can you please clarify those also?
    – J.Doe
    Aug 25, 2021 at 9:19

1 Answer 1


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Typically, the first question mark refers to flag and the second question mark refers to tx_witnesses

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