Spec + codegen
Define a counterparty dialect once; generate typed Java. Messages stay data on the wire — behaviour lives in your app.
Spec-driven · microsecond-class · 2026 ESP matrix benchmark
Four Hearts (4H) — Java FIX engine
Low-latency FIX infrastructure for FX ESP and sell-side integration — typed session objects from wire bytes, measured nine ways against QuickFIX/J and FIX Antenna on identical payloads.
Measured nine ways — not marketed
9 cells · identical ExampleBank ESP payloads · median p50 on TCP
5,000 warmup · 50,000 iterations · 3 runs per cell · _4h vs QuickFIX/J 2.3.2 vs FIX Antenna Java 2.27.0
| client ↓ server → | _4h | QuickFIX/J | FIX Antenna |
|---|---|---|---|
| _4h | FASTEST 21.6 µs | 104.3µs | 93.7µs |
| QuickFIX/J | 94.2µs | 77.0µs | 83.0µs |
| FIX Antenna | 89.9µs | 84.4µs | 63.5µs |
Homogeneous diagonal (bold green) for speed claims. Cross-engine cells ~84–104 µs for all stacks.
21.6 µs
Fastest matrix cell (p50, _4h↔_4h)
9 / 9
Client×server cells pass on TCP
38k
Quote ops/s on homogeneous diagonal
90 days
Free non-production evaluation
Fastest cell in a 9-way ESP matrix — every cross-engine pair passes on the wire with identical grouped payloads. Not a cherry-picked slide: re-run the matrix on your hardware.
The problem
Teams need low latency, stable memory, and clean integration without rebuilding session machinery for every counterparty.
- Open source — cheap, slow, tag soup, operational pain
- Commercial — fast, expensive, often still tag-oriented APIs
- In-house — years of dialect maintenance, fragile session logic
The 4H answer
Session pipeline
FIX bytes become typed session messages through a pub/sub kernel you wire once.
Embeddable kernel
A library, not a monolithic server. You own the process layout and deployment topology.
Measured, not marketed
21.6 µs p50 on the homogeneous diagonal; best client and server averages in the same 3×3 matrix. Honest caveats published.
Why desks care
- Fastest quote path, measured nine ways — not a single cherry-picked run.
- Best stack whether you send or receive — lowest row and column averages in the matrix.
- Interop is a test suite, not a slide — identical ESP payloads, all cross-engine pairs on TCP.
Proven in production
Barclays, Deutsche Bank, Citi, Goldman Sachs, Morgan Stanley, Currenex, Commerzbank, Lucid, Traiana, and other sell-side / venue profiles.
Start here
Free evaluation
Non-production licence · ExampleBank + Lucid · up to 2 concurrent FIX sessions.
Learn
FIX fundamentals and hands-on guides with the evaluation package (ExampleBank + Lucid).
4H Academy
Short lessons and quizzes — learn FIX and 4H with a playful track.
Contact
Enterprise, OEM, or tailored Professional plans — we reply within two business days.
Honest caveats: cite the homogeneous diagonal (21.6 µs) for speed claims; cross-engine cells are ~84–104 µs for all stacks. 4H does not claim sub-5 µs or “world’s fastest FIX.” Full methodology in the sales pitch.