Senior Full-Stack Engineer

Company details

Description of the offer

Are you an experienced engineer looking for an exciting start-up opportunity in the process of finding PMF?

Keep reading!

We’re Koast, on a mission to revolutionize Meta media buying with AI-powered workflows. We’re looking for a talented Senior Full-Stack Engineer to join our growing engineering team (currently 2 people!). As the third member of our technical team, you’ll take full ownership of core systems, from data models to production deployments. You’ll play a crucial role in building features that power sophisticated ad campaigns reaching millions of people globally.

What You’ll Do Daily

• Backend Mastery
  Architect, implement, and operate our Node.js + TypeScript services – data models through CI/CD – without hand-holding.
• Front-End Craftsmanship
  Ship React components using hooks and state libs, nail pixel-perfect UIs, and squash cross-browser quirks.
• LLM Feature Integration
  Design prompts, manage streaming, and build rate-limit/cost controls around GPT-class models.
• End to End Feature Lifecycle
  Take features from spec → prototype → code → deploy → monitor, owning each step without hand-holding.

Must-Have Technical Experience

• Node.js & TypeScript (5+ yrs) — you’ve owned production services from spec to scale.
• React (3+ yrs) — modern hooks, state libs, and deep browser-debug skills.
• End-to-End Product Mindset — you think in features, not tickets, and drive them all the way home.
• LLM-Powered Features — hands-on prompt design, streaming integrations, and cost/rate-limit handling.
• AI-Augmented Dev — Copilot/Cursor (or similar) are your daily co-pilots.

Nice-to-Have (Will Make Us Smile)

• NestJS or another opinionated Node framework
• Next.js / React Server Components
• Dev-ex tooling: GitHub Actions, automated testing, observability, profiling
• Design-system fluency: Tailwind, MUI, Chakra, or custom component libs

How You Work

We live by these values – if they sound like you, you’ll fit right in….

• Mastery: You push beyond “good enough,” constantly honing your craft.
• Push the Boundaries: You tackle ambitious challenges and unlock new possibilities.
• Embrace the Challenge: You collaborate shoulder-to-shoulder when the stakes are high.
• Responsibility: You own your commitments, deliver on time, and keep teammates aligned.
• Dedication: You dive head-first into tough problems, iterating until they’re solved.
• Collaboration: You communicate clearly, share knowledge freely, and build together.

Why Koast.ai?

• Early-Stage Impact
  Your work will define our architecture and ship features that 100+ customers rely on every day.
• AI & Ads at Scale
  Join the frontier of AI-powered media buying – supercharge budgets and decision-making in real time for some of the best ad teams in the world.
• Growth & Ownership
  Start as a contractor, grow into a full-time role, and potentially earn equity.
• Remote & Flexible
  Work from anywhere on your schedule—just deliver high-quality code (and have fun doing it!).

 Bonus: Send a 1–2 min video introducing yourself and why this role excites you—we’ll bump you to the top of the stack!

Ready to apply?

Email your resume, GitHub/portfolio links, and (if you like) that intro video to hello@koast.ai with the subject line “Koast to the moon.” In your email, we’d love to hear how you’ll make an impact here that no “regular” engineer could. That’s it!

Can’t wait to build the future of autonomous ad buying with you!

Location of employment

How to apply?