# NexusFIX - C++23 High-Performance FIX Protocol Engine

> Open-source C++23 FIX protocol engine. 3x faster than QuickFIX with zero-allocation design, AVX2 SIMD acceleration, and lock-free order book.

## NexusFIX

Ultra-low latency FIX protocol engine built with Modern C++23. 3x faster than QuickFIX with zero heap allocations on the hot path.

- [View on GitHub](https://github.com/Lattice9AI/NexusFIX)

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## Performance at a Glance

Measured on Linux with GCC 13.3, 100,000 iterations.

| Metric | Value |
|--------|-------|
| ExecutionReport Parse | 246ns |
| vs QuickFIX | 3x Faster |
| Throughput | 4.17M Messages/Second |
| Heap Allocations on Hot Path | 0 |

[See Full Benchmarks](https://silverstream.tech/nexusfix/benchmark)

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## Core Capabilities

Built for ultra-low-latency financial messaging with modern C++ best practices.

### Zero-Allocation Hot Path
Pre-allocated message pools and arena allocators eliminate GC pauses. Consistent sub-microsecond latency on the critical path.

### AVX2 SIMD Tag Parsing
Vectorized FIX tag parsing processes 32 bytes per cycle. 3x throughput improvement over traditional byte-by-byte parsers.

### Lock-Free Order Book
Wait-free concurrent order book with atomic operations. Supports millions of order updates per second without contention.

### FIX 4.2 / 4.4 / 5.0
Full protocol coverage from FIX 4.2 to FIXT 1.1 / FIX 5.0 SP2. Session management, heartbeat, and sequence number recovery built-in.

### Modern C++23
std::expected for error handling, std::span for zero-copy views, concepts for compile-time validation, consteval for compile-time computation.

### io_uring Async I/O
DEFER_TASKRUN + registered buffers + multishot recv. 7-27% faster I/O with ~30% fewer syscalls than epoll.

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## How It Works

### 1. Accept & Parse
Incoming FIX messages are received via io_uring async I/O and parsed using SIMD-accelerated tag extraction into zero-copy message views.

### 2. Route & Match
Parsed messages flow through a rule-based routing engine to the lock-free order book for matching or forwarding to downstream venues.

### 3. Respond & Log
Execution reports are serialized from pre-allocated buffers and sent back with nanosecond-precision timestamps and persistent journaling.

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## Presented at C++Online 2026

NexusFIX was presented as an open-content poster at C++Online 2026, the premier virtual C++ conference.

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## Dive Deeper

### Performance Deep Dive
Full benchmark tables, optimization phases, and technique comparisons against QuickFIX.
[Read more](https://silverstream.tech/nexusfix/benchmark)

### Interactive Q&A
182 expert-answered questions covering architecture, performance, C++23 techniques, and roadmap.
[Read more](https://silverstream.tech/nexusfix/chatbot)

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## Get Started with NexusFIX

MIT licensed. Drop-in replacement for QuickFIX with zero API friction.

```bash
git clone https://github.com/Lattice9AI/NexusFIX.git
cd NexusFIX
./start.sh build
```

- [Star on GitHub](https://github.com/Lattice9AI/NexusFIX)

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## Related Projects

- [QuantNexus](https://silverstream.tech/quantnexus/) - AI-Powered Desktop Quantitative Trading Platform
- [ClawNexus](https://silverstream.tech/clawnexus/) - The Internet for AI Agents