claude-dev-suite Fulcrum
C++ Electrum-protocol server. Faster than electrs for query throughput, at higher RAM cost.
Repo: github.com/cculianu/Fulcrum.
Setup
Bitcoin Core with txindex=1. Then Fulcrum:
[options]
datadir = /var/lib/fulcrum
bitcoind = 127.0.0.1:8332
rpcuser = ...
rpcpassword = ...
tcp = 0.0.0.0:50001
ssl = 0.0.0.0:50002
Indexes ~1-2 days; ~10-15 GB additional disk.
When to choose Fulcrum
- High-traffic public Electrum server.
- Power users with multiple wallets connecting.
- BTCPay backend with many invoices.
When to choose electrs
- Personal use, low traffic.
- Resource-constrained devices.
- Simpler config preferred.
Compatibility
Same as electrs — Sparrow, Electrum, BTCPay, etc.
Common bugs
- High RAM usage (8+ GB) → tune
db_max_open_files,cache_size. - TLS cert mismatch on SSL endpoint → wallets fail to connect.
- Bitcoin Core RPC connection drops → Fulcrum reconnects but may miss blocks; restart in extreme cases.