AI / ML Engineer

About Goaltree

Goaltree is a habit tracker and AI goal planner. Tell it what you want and AI breaks it into milestones, daily tasks and habits, then a coach with a voice, a face and a personality keeps you on track. It runs on web, iPhone and Android in six languages.

AI is the product, not a feature. One sentence becomes a full plan with milestones, targets, tasks and habits, streamed as it's written. A coach chats, calls you with realtime voice and a lip-synced face, logs a meal from a photo, and changes your plan with tools.

We use hosted frontier models (including xAI's Grok for realtime voice, TTS and vision, and fast inference providers for background tasks) and spend our effort on prompts, tools, evaluation, latency and cost.

What you'll do

• Improve goal decomposition: better plans, better questions, streaming that feels instant, sensible fallbacks when a model is slow or wrong.
• Design and harden coach tools (add to Today, set deadlines, freeze a goal, log a habit amount, post to a grove) across text chat and realtime voice.
• Push realtime voice further: turn-taking, interruptions, focus sessions, quick-call mode, resumable sessions, transcription accuracy with key terms.
• Build evaluation sets and regression checks for plans, coach replies and tool use, so changes are measured, not guessed.
• Own safety and tone: coach personas and characters that stay supportive, never abusive, and drop the act when someone is struggling.
• Track cost and latency per feature and per user, and make the trade-offs that keep the product fast and affordable.

What we're looking for

• 3+ years shipping LLM-powered features to real users, not just prototypes.
• Strong prompt engineering and tool/function-calling experience, with structured outputs and streaming.
• Hands-on with evaluation: you build test sets and catch regressions before users do.
• Solid TypeScript; our AI code lives in Convex actions alongside the rest of the backend.
• Care about the human on the other side: the coach should feel helpful, honest and kind.

Nice to have

• Realtime speech-to-speech or WebRTC/WebSocket audio pipelines.
• Vision models, TTS and voice cloning.
• Model routing across providers, caching and cost control.
• Experience with MCP or agent tool ecosystems.

How we work

• Remote-first and async. We write things down, keep meetings rare and short, and protect long stretches of focus time.
• Small team, big surface area. You will own whole features end to end: idea, design, build, ship, measure.
• AI-native. We build with AI coding tools every day and expect you to be fluent with them, while still caring about every line that ships.
• Quality bar: fast, accessible, translated, tested. Every feature lands on web and mobile, in all six languages.

How to apply

Send a short note about something you built that you are proud of, plus a link to your work (GitHub, portfolio, a live product), to jobs@goaltree.ai with the role in the subject line.