Staff Backend Architect — Scalable AI Hiring Platform

Socket.dev; Hinoba-an; On-site; PHP 1,800,000 - 2,800,000; Full time

Job summary

FirstWork is hiring a Staff Backend Engineer to architect scalable AI-powered HR operations platforms. You will own core domains such as the agent runtime, rules engine, and data models, while pushing LLM-driven features deeper into the product and ensuring deterministic, auditable outcomes.

You will design safety, evaluation, and data-architecture components to support enterprise-scale AI decisions across global workflows, with a focus on performance and reliability.

Qualifications

• 8+ years of professional backend engineering experience.
• Experience scaling a first architecture to enterprise scale.
• Deep relational database expertise with production saturation diagnosis.
• Production experience with LLM or vision-model systems and cost control.
• Experience with multi-tenant, configurable products.
• Measurement-first approach: profiling and traces before opinions.
• Influence through clear writing and demonstrated results.

Responsibilities

• Take end-to-end ownership of core domain: the agent runtime, the compliance and rules engine, the worker data model, or integrations.
• Push LLMs and agentic AI deeper into the product, and draw the line between inference and deterministic rules.
• Design the safety properties of agents that act in external systems, including idempotency, retries, isolation, and human escalation.
• Build the evaluation and accuracy infrastructure that makes AI decisions defensible in a regulated context.
• Keep inference viable at scale through model routing, caching, and batching, with cost per transaction as a tracked metric.
• Design data models with long‑lived constraints, including audit logs, compliance clocks, and credential lifecycles.
• Drive the data architecture roadmap: read replicas, logical sharding, CDC‑fed projections, and a search tier.
• Enforce multi‑tenancy, permissions, and audit trails as invariants guaranteed by design and by test.
• Act as a technical lead through design review, incident command, and mentoring senior engineers.
• Work directly with product and customers to turn bespoke requests into platform capabilities.

Skills

Backend engineering

Relational databases

Distributed systems

LLMs / AI models

Multi-tenant architecture

Performance optimization

Tools

PostgreSQL

Distributed systems tooling

Job description

FirstWork is hiring a Staff Backend Engineer to architect scalable AI-powered HR operations platforms. You will own core domains such as the agent runtime, rules engine, and data models, while pushing LLM-driven features deeper into the product and ensuring deterministic, auditable outcomes.

You will design safety, evaluation, and data-architecture components to support enterprise-scale AI decisions across global workflows, with a focus on performance and reliability.