Flex Crossroads Talent Jobs (NOW HIRING)

Title: Sr. Full-Stack Founding Engineer — AI Platform

Department: Technology / Software

Location: Kansas City, MO — Crossroads Arts District (preference in-office with flex to work from home as needed)

Type: Direct Hire / Perm

Status: US Citizen / Green Card Permanent Resident / W2 Exempt - Unable to Sponsor or work C2C

Salary: $150K–$200K (some flex, based on talent)

Reports To: Chief Technology Officer

SUMMARY:

Our client is a sixth-generation, family-owned heavy/civil contractor based in Kansas City, in business since 1880. They have built 845+ bridges and placed 3,500+ lane miles of pavement across the Midwest and is currently behind some of the region's largest infrastructure projects. Underneath that 145-year track record, our client is investing in modern technology — including a new AI-powered software platform meant to bring everyone on a complex project (contractors, craftsmen and field supervisors, estimators, architects, mechanical and electrical engineers, quality control, and project management) together on one system.

As a Sr. Full-Stack Founding Engineer, you will help build this platform from an early stage, working directly with the CTO. This is a high-ownership, full-stack role — you own features across the entire stack, make real architecture decisions, ship them, and keep improving on the results. This is not a maintenance role on someone else's system; it is a builder's seat inside a company that builds physical infrastructure and is now investing seriously in software and AI.

RESPONSIBILITIES:

Build & Own the Stack

• Design, build, and ship full-stack features across frontend, backend, and data layers.
• Own systems end-to-end — auth, multi-tenancy, billing, and deployment — as connected concerns, not isolated tickets.
• Make pragmatic architecture decisions early, ship them, and refine as the product and requirements evolve.

AI & Data

• Build and maintain Python services that power data pipelines and AI workloads.
• Integrate LLMs (Claude / Anthropic and others) into real product workflows — not demos.
• Apply sound data modeling and query design in Postgres to keep the platform fast and reliable as it scales.

Integration & Reliability

• Wire up third-party and enterprise APIs, handling authentication, rate limits, and pagination.
• Build systems that recover gracefully when upstream services misbehave.

Team & Culture

• Collaborate directly with the CTO and early team to set technical direction.
• Contribute to a fast-moving, low-process culture that values ownership, directness, and judgment.

REQUIREMENTS:

• 4+ years building production SaaS — you have owned auth, multi-tenancy, billing, and deployment as a system, not as someone else's problem.
• Full-stack TypeScript — comfortable across the frontend and backend; our stack is Next.js with a modern Postgres-backed backend-as-a-service layer (Supabase/Deno).
• Front-end craft — as a founding engineer you own UI design decisions and build clean, functional user-facing features in React / Next.js and TypeScript.
• Python web service experience — FastAPI, Flask, Django, or similar; we run Python services for data pipelines and AI workloads.
• LLM integration experience — you have shipped a real product feature using an AI model (Claude, GPT, or similar) in a production workflow.
• Third-party integration experience — you have wired up enterprise APIs, handled rate limits, and recovered gracefully when upstream services misbehave.
• Strong Postgres — row-level security, views, and query optimization; not just ORM-level familiarity.
• Data management & analysis — comfortable working with data across systems, validating it, and analyzing it to make sure it's accurate and usable, not just stored.
• Early / founding engineer background — you have built in a small-team environment before and know how to make a decision, ship it, and fix it if it's wrong.
• Open-stack orientation — modern web/cloud tooling; this is not a Java or .NET shop
• Cultural fit — ownership, directness, and the ability to move fast without heavy process.

NICE TO HAVE:

• Direct experience with Claude / Anthropic models.
• Experience with Supabase and Deno Edge Functions specifically.
• E-commerce or marketplace platform experience (catalog, cart, checkout, payments, order lifecycle).
• Construction tech, field-operations software, or other complex multi-stakeholder platform experience.

WHY THIS ROLE:

• Real ownership on a platform being built from the ground up, backed by an established, financially stable company.
• Work directly with a CTO who brings 20+ years of SaaS leadership experience.
• Fast-moving hiring process; compensation is open for the right person.