Principal Software Engineer

About Downstream

Downstream is a marketplace platform transforming the waste and construction industries from the ground up. We're on a mission to bring simplicity, transparency, and sustainability to two of the most essential — but often overlooked — sectors of our economy.

We make it easy for contractors, builders, and businesses to find and book critical services like dumpster rentals, hauling, site services, and equipment — all in a few clicks. No endless calls, no confusing pricing, no waiting around. Our platform connects customers with vetted, reliable providers so they can get what they need, when they need it.

We're not just about convenience — we're about impact. By streamlining logistics and digitizing the supply chain, we're helping reduce waste, cut emissions, and build a cleaner, more sustainable future. Let's build better, together.

About the role

We're looking for a Principal Software Engineer to shape Downstream's company-wide technical strategy and solve our most complex engineering challenges. You'll set long-term direction for the marketplace platform and its AI-native capabilities, ensuring our Django foundation, data architecture, and agentic systems can support the next stage of growth. You'll advise leadership, lead critical cross-team technical decisions, and establish engineering standards that scale with the business.

What you'll do

• Define company-wide technical direction for the marketplace platform, including Django services, APIs, data models, and system boundaries
• Own highly complex, cross-team technical problems that affect platform scalability, resilience, security, and business continuity
• Set architectural strategy for agentic AI systems, including multi-agent coordination, planning, tool use, memory or state management, and controlled execution
• Determine when to build, adopt, or extend frameworks such as LangChain, LangGraph, OpenAI, Hugging Face, or custom orchestration
• Establish the technical principles and reference architectures for embedding intelligent decisioning into logistics, pricing, supplier matching, and other core workflows
• Advise executive and product leadership on technical strategy, investment priorities, architectural risk, and build-versus-buy decisions
• Define company-wide standards for software quality and production AI systems, including evaluation, security, privacy, observability, reliability, and cost controls
• Lead resolution of high-impact technical risks and align senior technical contributors across teams
• Develop Staff and Senior engineers through technical mentorship and by creating clarity around difficult architectural decisions

Role specifics

• Ownership: accountable for technical strategy and the resolution of the company's most complex cross-team engineering problems
• Architecture: sets durable platform and AI architecture principles that guide multiple teams and product generations
• AI responsibility: establishes how agentic systems are designed, evaluated, governed, and operated as a core part of the marketplace
• Leadership: advises company leadership and creates alignment across engineering, product, and business stakeholders

Who you are

• You have a distinguished record of designing and evolving large or business-critical software systems, with deep Django/Python expertise or the ability to lead within that stack
• You've led company-wide or multi-team architecture and resolved technically complex, ambiguous problems
• You have deep experience with production AI/LLM systems and agentic architectures, including reasoning, planning, tool use, orchestration, and evaluation
• You can make high-consequence decisions about frameworks, architecture, data, security, reliability, and long-term technical investment
• You can translate technical strategy into practical roadmaps and standards that teams can execute
• You're a trusted technical advisor who communicates clearly with engineers, product leaders, and executives
• Experience in construction technology, logistics, equipment rentals, or marketplace platforms is a plus

Compensation

$170,000–$210,000 per year (Series A compensation band).

Benefits

Downstream is an equal opportunity employer. We consider all applicants for employment without regard to race, color, religion, sex, sexual orientation, gender identity or expression, national origin, age, disability, genetic information, veteran status, or any other protected status under applicable law.

• Medical, dental, and vision insurance
• 401(k) with a company match
• Company equity — be an owner in what we're building
• Paid time off, paid holidays, and floating holidays
• Parental and bereavement leave