Location: Remote Type: Paid Internship — Part-time or Full-time (3–6 months)

About Us CelestiOS is building the Decision Layer for your day. Backed by LvLUp ventures

Most calendars assume every hour is equally usable. They aren't. We are building an adaptive AI system that reads your calendar, your patterns, and your wearable data (Oura, Whoop, Apple Health) — and decides what you should actually do, when, and what to skip.

We are a fast-moving, founder-led startup building in public. We aren't trying to be another productivity tool; we are bridging the $20B calendar market and the $5B self-tracking market to fix how knowledge workers actually execute.

The Role We're looking for an AI Engineering Intern who is obsessed with building intelligent systems and equal parts scrappy. You won't be fetching coffee or fixing minor CSS bugs. You will be building the core brain of the product—working directly with the founder to turn complex decision-support theories into working AI prototypes.

We sound like a sharp engineer who ships fast and cares about the details. Your code should sound the same.

What You'll Do

• Build and ship AI-powered product features and prototypes from zero to one
• Work directly with LLMs, AI agents, RAG pipelines, and personalization systems
• Develop the backend services that connect calendars, health APIs, and our decision engine
• Experiment with recommendation algorithms that restructure a user's day based on cognitive load and energy
• Collaborate directly with the founder on product vision and technical architecture

Who You Are

• A Python wizard who writes clean, fast code
• Deeply familiar with LLMs, AI agents, or machine learning—you actually tinker with them, not just read about them
• Experienced with APIs and backend development, with a strong grasp of system design
• A self-starter who doesn't wait for a perfectly scoped Jira ticket to start building
• Someone who can see a Founding Engineer role in their future

Bonus Points

• You have hands-on experience with LangChain, or LlamaIndex