Founding AI Engineer

RecruitAbility Ltd; Philadelphia (Philadelphia County); On-site; USD 120,000 - 160,000; Full time

Job summary

RecruitAbility Ltd. is seeking a senior product/full-stack engineer to take the sole technical lead role, building a production-grade system from the ground up. You will work directly with the founders to decide architecture, data models, and how to scale for multiple customers.

You will own AI agent integration, maintain a deterministic core, and build evaluation harnesses to validate features before shipping, shaping the product as it evolves with customers.

Qualifications

• 7–12 years of experience as a product or full‑stack engineer.
• Shipped a data-heavy B2B application end to end.
• Built AI agents that run in production, not chatbot wrappers.
• Built evaluation or testing systems for AI-driven features.
• Able to explain where numbers come from and why decisions were made.
• Comfortable working alone, moving fast, and making decisions without a large team.
• Views an evolving product as something to shape, not a fixed spec.
• Current stack is Python on Postgres; language/tools open to new options.

Responsibilities

• Own end-to-end product development, from architecture to production.
• Decide whether to extend current code or rebuild for scale, defending the choice.
• Design data models and multi-customer schemas that grow over time.
• Create an evaluation harness to prove AI features work before shipping.
• Translate customer conversations into working data models, often without a formal spec.

Job description

Our client is a small, founder-led B2B consulting and advisory company with paying customers and a working product concept. The founders have built the initial product themselves, and now need their first dedicated engineer to take it to a finished, production-grade system built to scale. This is a ground-floor role: you’ll work directly with the founders, make the core architecture calls, and shape how the company builds software for years to come.

The opportunity

You’ll be the sole engineer for a stretch, owning the product end to end. You’ll decide whether to extend what exists or rebuild it, and you’ll defend that call. The software principle is simple: the system drafts, people decide. That means AI agents doing real work in production, sitting on top of a reliable, deterministic core.

What you’ll own

• The agentic layer: production AI agents that use tools, with the LLM treated as a component that can fail rather than as the product.
• A deterministic, well-tested core that agents call as a tool, producing results that are reproducible and traceable to their inputs.
• An evaluation harness that proves AI-driven features work before they ship.
• Data modeling and schema design for multi-customer data that grows over time.
• Translating customer conversations into working data models, often without a formal spec.

What we’re looking for

• Roughly 7 to 12 years of experience as a product or full-stack engineer.
• Has shipped a data-heavy B2B application end to end.
• Has built AI agents that run in production, not chatbot or chat-wrapper builds.
• Has built evaluation or testing systems for AI-driven features.
• Cares about getting the numbers right and being able to explain where they came from.
• Comfortable working alone, moving fast, and making decisions without a large team around you.
• Sees an evolving product as something to help shape, not a spec to implement.
• Language and stack are open, the current stack is Python on Postgres.

Nice to have

• Founding engineer or early-stage startup experience.
• Experience building data pipelines from messy business systems.
• Familiarity with agent tooling and protocols such as MCP.

Compensation

Competitive base salary with meaningful founding equity. Especially interested in candidates who want to trade some base salary for a larger ownership stake and a real share in what they build.