I work on the plumbing of electronic markets: FIX engines, order gateways, and the post-trade and settlement systems behind them. Mostly Java, some Solidity. I like problems where correctness is not optional, where a dropped message or a drifted sequence number is a real loss, not a retryable error.
Most of what's worth looking at is merged into other people's projects. 👇
🔗 quickfix-j/quickfixj #1181 · merged into QFJ 3.0.1
A disabled, disconnected FIX session was skipping its scheduled reset. An early return in Session.next() sat above the SessionSchedule block, so messages queued via sendToTarget() (and the sequence numbers they advanced) were never cleared at the scheduled boundary, causing message loss when the counterparty reconnected and logged on. Moved the guard below the schedule block so the reset runs; added a regression test reproducing the exact scenario. Reviewed line-by-line by the maintainer.
🔗 hyperledger/besu #10127 · Hyperledger Besu
Made three hard-coded DiscV5 peer-discovery constants (interval, timeout, minimum peer ratio) configurable via CLI flags. Defaults unchanged, so existing behaviour is preserved.
🔗 kafbat/kafka-ui #1768 · merged into 1.5
fillKey() was passing empty headers to the key deserializer instead of the actual record headers, breaking custom serdes that resolve their schema from a registry via headers. One-line fix to match fillValue(), plus a unit test.
🔗 redis/jedis #4482 · Redis Java client
Stabilised a flaky CI failover test: a 20ms freeze window could expire mid-loop on a loaded runner and trigger a spurious second failover attempt. Widened the timing windows proportionally. Test-only, no production change.
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Distributed trade lifecycle simulator, compliance through settlement. Event-driven Spring Boot microservices over Kafka, FIX ingress, T+2 settlement, MiFID II reporting.
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Overcollateralized DeFi stablecoin with Chainlink oracles. 91.65% test coverage, 20 invariants, CI/CD with Slither and Aderyn.
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On-chain IPO lifecycle infra for post-Aug-2025 HKEX rules: sealed commit-reveal bookbuilding, Merkle-verified allocation, real-time float monitoring. Top 7 finalist, DeFi track, HashKey Chain Horizon Hackathon (Hong Kong).
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🚧 ForgeFIX/J (WIP)Low-latency FIX order gateway. QuickFIX/J ingress, Aeron/Agrona bus, in-memory matching engine, Chronicle Queue persistence, SBE codecs, JMH benchmarks.
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Systems 
Markets 
Contracts 
Data 
