Senior Backend Engineer

🚀 Hiring: Senior IC Backend Engineer (Routing, Ledger & Settlement) | AI-Native Settlement Network | UK, NL, PT

At UNYX AI, we are building a secure, institutional-grade programmable settlement and routing infrastructure for NBFIs, EMIs, PSPs, custodians, and market makers. For the first time, we are creating a true programmable alternative to legacy cross-border payment monopolies—redefining how global ecosystems orchestrate multi-hop asset execution.

Trust and absolute execution precision are our currencies. We operate a high-density, low-latency environment with maximum engineering rigor and zero corporate bureaucracy. Right now, we are looking for an elite Senior Individual Contributor (100% hands-on) to own the core transactional, pathfinding, and accounting logic of our system.

Note: This is a pure builder role for an engineer who wants to stay deep in complex algorithms, distributed ledger codebases, and strict financial data structures—not a people manager or a DevOps administrator.💼 What We Offer:

• The Setup: A full-time, long-term contract as an independent service provider. Remote-first flexibility with structural alignment in the UK, NL, or PT time zones.
• Direct Architecture Ownership: Work side-by-side with the founders to shape our core engine. You won't just execute tickets; you will write the economic constraints that safeguard transaction volumes.
• Highly Competitive Compensation: Premium contract rates tailored for top-tier engineering talent capable of maintaining strict mathematical determinism under real-world conditions.

🛠️ What You Will Do:

You will own the backend engineering domain for our core transaction orchestration and financial data architecture. Your daily domain will center on graph theory, multi-currency balance spaces, and transactional atomicity:

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• Build Graph-Based Routing & Pathfinding Engines: Design and implement highly optimized pathfinding pipelines (utilizing Dijkstra on directed graphs weighted by delivered quote metrics) to calculate real-time, multi-hop conversion paths (≥3 hops) across fiat corridors and tokenized assets.
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• Architect Low-Latency Bidding Logic: Program our continuous RFQ loop aggregation system, managing asynchronous quote fanouts, partial fills, deterministic maker selection scoring (weighted price, inventory, latency, reputation), and multi-hop route recomposition.
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• Engineer the Distributed Double-Entry Ledger: Direct our split-storage ledger layer, pairing specialized systems like TigerBeetle (for immutable, ultra-high-performance debits, credits, and code bitmasks) with an operational PostgreSQL sidecar acting as a high-speed read model.
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• Model Complex Financial Mathematical Behaviors: Build code handlers to execute precise programmatic fee strategies—translating complex multi-tenant data structures like Affine linear models, cliff tiering, progressive tranche splits, and min-max collar clamps into deterministic rounding logic.
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• Enforce State-Machine Atomicity & Failure Rollbacks: Build idempotent saga execution patterns handling per-hop atomicity, dynamic timeout mitigations (quote TTL tracking), and compensation simulations that execute placeholder reversing entries if a mid-route settlement aborts.
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• Manage Financial Edge Cases ("Bleed" & Slippage): Build asynchronous pipelines that reconcile intent vs. reality; abstracting network transaction anomalies (on-chain gas burning, pool slippage, and variance balances) by capturing actual confirmation webhooks before writing immutable entries.

🎯 Who We Are Looking For:

• FinTech or Quantitative Core Veteran: You have years of experience deep within financial execution engines, ledger accounting boundaries, or electronic communication networks (ECNs). You are obsessed with strict double-entry standards, where the sum of debits minus the sum of credits must equal zero.
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• Master of Complex Data Structures: You navigate structured polymorphic schemas easily (such as heavily nested ISO 20022 payloads or multi-layer JSONB configuration manifests) and enforce data validation discipline at the application boundaries.
• Security & Isolation Mindset: You understand that "atomicity" is probabilistic until finality. You have hands-on experience enforcing end-to-end cryptographic patterns—such as tokenizing write operations via strict client-side UUID v4 idempotency keys and isolating automated signature components inside Trusted Execution Environments.
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• Deeply AI-Native Builder: You don't just copy-paste from LLMs; you use agentic coding loops, automated simulations, and advanced scripting daily to fuzz-test code paths, inject transactional faults, and validate data topology at scale.

💻 The Stack:

• Core Languages: Strong production proficiency in fast, strongly-typed systems languages—specifically Go (Golang), Rust, C++, or robust modern JVM environments (Java/Kotlin).
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• Storage Systems: Expert-level PostgreSQL (complex JSONB modeling, recursive queries, row-level concurrency locking) and experience with or strong interest in TigerBeetle or similar specialized financial databases.
• Observability & Formats: OpenTelemetry for deep trace coverage across complex multi-step sagas; JSON Schema verification engines; structural protocol communication.

📩 To Apply: Please send your CV/profile directly to jobs@Unyx.ai

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