I'm running a full node, because I want to support the Bitcoin network, and because I'm interested in the backend mechanisms in Bitcoin.

Now, SegWit2x is approaching. I believe it's important for Bitcoin to increase the block size, so I would like to somehow support the doubling of the block size. Can I somehow support SegWit2x through my choice of full node software? If I can choose between Bitcoin Core, Bitcoin ABC, Bitcoin XT, and Bitcoin Classic: Are there any feature differences that would make those more or less supportive of the block size doubling?

  • 2
    As it stands, asking which one is "best" is primarily opinion based, it would be better to reword your question to ask which software is available to run Nov 6, 2017 at 22:20

2 Answers 2


If I can choose between Bitcoin Core, Bitcoin ABC, Bitcoin XT, and Bitcoin Classic

None of these software support Segwit2x. Currently your only choice of Full node software for Segwit2x is btc1.

  • Thanks! A follow-up question: Am I correct in thinking that plain Bitcoin Core currently does not support SegWit2x? Nov 7, 2017 at 6:51
  • Yes, Bitcoin Core does not support segwit2x.
    – Ava Chow
    Nov 7, 2017 at 6:58
  • But it says here that BTC1, Bitcoin Unlimited & Bitcoin Classic are compatible.... segwit2x.github.io/segwit2x-announce.html
    – confused
    Nov 7, 2017 at 21:32
  • And this is alert on the main unlimited site pointing to this statement : medium.com/@peter_r/… - where it says for example that: "What this means for Bitcoin Unlimited node operators: [...] No action is required from Bitcoin Unlimited node operators."
    – confused
    Nov 7, 2017 at 21:36

Bitcoin Core will not follow the B2x blockchain tip, as B2x requires a block exceeding Bitcoin's blockweight limit at fork height which Bitcoin Core will reject as invalid.

BTC1 is the reference implementation of the New York Agreement and thus will follow the B2x blockchain.

Bitcoin Unlimited is an implementation of the Bitcoin protocol that doesn't enforce the current blockweight limit and thus will follow the B2x blockchain.

BitcoinABC is an implementations of the Bitcoin Cash protocol and will thusly not follow the B2x chain.

I've not kept up to date on Bitcoin XT and Bitcoin Classic. It seems that today the former is an implementation of the Bitcoin Cash protocol and the latter may be following Bitcoin but allowing a higher blockweight.

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