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I'm trying to develop an SPV Bitcoin client which makes use of a library requiring bitcoin core (a running bitcoind service). However, from what I understand, Bitcoin Core is full node, meaning that it stores the whole blockchain.
My question is: there exists a service which is similar to bitcoind (that is it provides a JSON-RPC server), without needing the whole blockchain?
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Yes, bitcoind with pruning is similar to bitcoind, though some RPCs are disabled (naturally, because of pruning).
bitcoind in pruning mode does not store the whole blockchain, and can reduce your space usage to 2GB instead of 85GB.
See the release notes here and here.
Update: There is also a Full Block SPV wallet PR by Jonas Schnelli. Which is even lighter than pruning mode, since it only downloads blocks from the creation of the wallet.
Thanks. I didn't know that bitcoind had a pruned version. This could actually be very useful.
In the meanwhile I found a good compromise by adopting the bitcored wallet service, which provides with a full node server that can serve a number of light wallet clients. – FedFranzoni – 2016-10-28T11:32:50.320
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As Alin explained today the lightest version is pruned mode. However there are pull requests for an even lighter version, called full block downloading SPV mode, or full-SPV mode.
Keep an eye on these two pull requests. You are also free to contribute:
Complete hybrid full block SPV mode
Add simple light-client mode (RPC only)
2"full node" doesn't mean it stores the full blockchain. It means it's a fully validating and has downloaded the while thing, but it not necessarily keeps everything. You may want to look into pruning for more info on that. – Jannes – 2016-10-07T20:57:20.463
@Jannes: Thanks for the clarification. However, as you say, it still needs to download the whole chain (thus requiring a certain amount of disk space). So my question still applies: I need something lighter than a full node, that is an SPV working with headers only, which provides an RPC service, similar to that offered by bitcoind. – FedFranzoni – 2016-10-10T15:15:11.130
1It needs to download the whole blockchain, but it doesn't need to store it. You don't need more than a few GB of disk space. An SPV client does not provide you with the same security guarantees and trustlessness as a full node. – Jannes – 2016-10-11T17:20:10.220