Founding Software Engineer - YC Backed AI Startup
Day One Partners is working with a Y-Combinator backed AI startup thats building a platform for product and engineering teams to integrate Large Language Models (LLMs) into their software. They are growing fast and looking for a Founding Full Stack AI Software Engineer to join their core team.
This role is fully in-person, working side-by-side with the CEO, CTO, and engineers at their Woodland Hills, Los Angeles office. Its a hands-on, high-impact opportunity to help shape both the product and the company at an early stage.
About the Role
As a Founding Engineer, youll play a critical role in designing and building AI-powered tools for software teams. Youll work across the stack, collaborating directly with leadership to deliver features that solve customer problems. This isnt a role for someone who just takes ticketsthis is for someone who cares about the user experience, wants to know how their code impacts customers, and is excited to build from scratch.
What Youll Do
Work closely with the CTO and founding team to design and develop core product features
Build end-to-end systems across the stack (frontend, backend, and AI components)
Develop AI-powered features using LLMs and frameworks like LangChain, Llama Index, and OpenAI
Implement scalable architectures with a focus on reliability and performance
Ship production-ready code with proper testing and documentation
Directly impact product decisions and strategy based on customer feedback
What Were Looking For
Currently located in Los Angeles (required)
4+ years of software engineering experience, including at least 1 year at a senior level
2+ years of hands-on experience developing AI applications with LLMs, including retrieval-based methods, fine-tuning, or agent-based architectures
Experience with AI frameworks such as LangChain, Llama Index, OpenAI, or similar
Strong skills in Svelte, Python, TypeScript, and Postgres
Excited to work in-office, Monday through Saturday, with a small, tight-knit team
Comfortable in an early-stage startup environment where speed, ownership, and learning are core to success
Nice to Have
Experience deploying, monitoring, and maintaining LLMs in production
Previous startup experience, especially in fast-growth environments
Why Join
Get in at the ground level of a Y-Combinator backed AI startup with a proven leadership team
Work alongside highly experienced founders with track records scaling companies to $100M+ in revenue
Build products that help teams bring AI-powered features to their users without the need for in-house AI expertise
Have a major impact on the companys success and growth
Competitive salary and meaningful equity
Be part of a fast-moving team that values hard work, customer focus, and continuous learning
If youre an engineer passionate about AI and excited to help build a foundational platform, reach out to Day One Partners to learn more. For immediate consideration, email your resume to [email protected] with the subject Day One YC SWE
Apply Now
This role is fully in-person, working side-by-side with the CEO, CTO, and engineers at their Woodland Hills, Los Angeles office. Its a hands-on, high-impact opportunity to help shape both the product and the company at an early stage.
About the Role
As a Founding Engineer, youll play a critical role in designing and building AI-powered tools for software teams. Youll work across the stack, collaborating directly with leadership to deliver features that solve customer problems. This isnt a role for someone who just takes ticketsthis is for someone who cares about the user experience, wants to know how their code impacts customers, and is excited to build from scratch.
What Youll Do
Work closely with the CTO and founding team to design and develop core product features
Build end-to-end systems across the stack (frontend, backend, and AI components)
Develop AI-powered features using LLMs and frameworks like LangChain, Llama Index, and OpenAI
Implement scalable architectures with a focus on reliability and performance
Ship production-ready code with proper testing and documentation
Directly impact product decisions and strategy based on customer feedback
What Were Looking For
Currently located in Los Angeles (required)
4+ years of software engineering experience, including at least 1 year at a senior level
2+ years of hands-on experience developing AI applications with LLMs, including retrieval-based methods, fine-tuning, or agent-based architectures
Experience with AI frameworks such as LangChain, Llama Index, OpenAI, or similar
Strong skills in Svelte, Python, TypeScript, and Postgres
Excited to work in-office, Monday through Saturday, with a small, tight-knit team
Comfortable in an early-stage startup environment where speed, ownership, and learning are core to success
Nice to Have
Experience deploying, monitoring, and maintaining LLMs in production
Previous startup experience, especially in fast-growth environments
Why Join
Get in at the ground level of a Y-Combinator backed AI startup with a proven leadership team
Work alongside highly experienced founders with track records scaling companies to $100M+ in revenue
Build products that help teams bring AI-powered features to their users without the need for in-house AI expertise
Have a major impact on the companys success and growth
Competitive salary and meaningful equity
Be part of a fast-moving team that values hard work, customer focus, and continuous learning
If youre an engineer passionate about AI and excited to help build a foundational platform, reach out to Day One Partners to learn more. For immediate consideration, email your resume to [email protected] with the subject Day One YC SWE
Apply Now