Senior Full-Stack Engineer – AI-Powered Voice Technology

Founded in 2014, Underdog.io is the 2nd largest US-based hiring marketplace for tech and product talent. With over 650 hiring partners in pre-seed, seed, and series A-C looking to hire full-time skilled engineers, data, and product professionals. One of our hiring partners founded in 2024 recently received 5M in seed funding and is looking to add a Founding Engineer.

About the Role

We’re building the future of AI-driven voice technology, and we need a Senior Full-Stack Engineer to architect and ship high-impact features that directly shape our product and revenue. You’ll work at the intersection of cutting-edge AI, scalable infrastructure, and customer-facing applications—owning projects from 0→1 prototyping to 1→n scaling.

This is a high-leverage role where you’ll collaborate with top AI researchers, optimize large-scale audio data pipelines, and deploy real-time ML models that redefine how users interact with voice technology. If you thrive in fast-moving, early-stage environments and want to build foundational AI infrastructure, we’d love to hear from you.

What You’ll Do

• Build end-to-end, full-stack features that directly impact customers and revenue.
• Solve high-stakes audio AI challenges, from scalable data pipelines to real-time ML model deployment.
• Drive technical decisions at the frontier of AI, working alongside world-class researchers.
• Own and architect solutions from 0→1 prototyping to 1→n scaling, shaping our core product and infrastructure.

Technical Challenges You’ll Tackle

• Architect and ship customer-facing full-stack features that enable rapid iteration.
• Design scalable engineering solutions for processing and analyzing terabytes of audio data.
• Optimize data pipelines for large-scale audio dataset generation and quality control.
• Develop and deploy audio-focused ML/LLM models, from research to production.

Who You Are

• 3+ years as a senior full-stack engineer with startup experience (1-2 years at an early-stage or high-growth startup).
• Proven track record of shipping end-to-end features that drive revenue and user impact.
• Leadership presence—able to mentor junior engineers and drive technical discussions.
• Exceptional at breaking down complex problems and communicating system designs.

Technical skills:

• Frontend: Next.js, TypeScript, TailwindCSS
• Backend: Node.js, tRPC, PostgreSQL
• Experience (or strong interest) in audio AI, signal processing, or ML deployment

Ideal Background

• CS degree from a top 25 university (or equivalent experience).
• Startup-minded—you thrive in ambiguity and move fast.
• Passion for voice technology, AI, and building from the ground up.
• Startup-minded builders.

Why Join?

• Work on bleeding-edge AI with a world-class team.
• Build foundational infrastructure for a category-defining product.
• Competitive compensation, equity, and the chance to shape the future of voice tech.