Senior+ Data Scientist - ML & Image Generation

Data Scientist

Build and optimize the ML pipeline behind Stickerbox, an AI-powered voice-to-sticker printer for kids.

Hapiko is a Brooklyn-based company building the future of play. Founded by Arun Gupta (former CEO of Grailed, which sold to GOAT Group in 2022) and Bob Whitney (Anthropic, NYT Games), we're on a mission to create safe, hands-on AI experiences that fuel kids' imaginations rather than replace them.

Our first product, Stickerbox, is the world's first voice-to-sticker printer. A device that instantly transforms a child's spoken ideas into printable, colorable stickers. We sold out our first run shipping for the holidays, and it's already being called "one of the first products to make AI feel magical for kids and grounded for parents."

We have a $7M funding round led by Maveron (backers of Lovevery), Serena Ventures, and Ai2 (The Allen Institute). Stickerbox is bringing imagination to life for kids nationwide!

The technical challenge is real. We're running real-time audio transcription, proprietary content safety systems, and custom image generation, all serving thousands of concurrent users with sub-second latency. We're training our own models from scratch, optimizing for kid-friendly aesthetics, and building safety guardrails that actually work. We need a Data Scientist to own data quality, evaluation, and ML optimization across this entire pipeline. You'll work with the team to define what to train on, how to measure success, and how to make our models better every day.

Model Training & Data

- Build and curate large-scale image datasets for training custom models

- Design annotation pipelines and data quality processes

- Analyze training runs and model outputs to guide iteration

- Work with our team to define what to train on and how to evaluate it

ML Pipeline Optimization

- Optimize our transcription pipeline for accuracy and latency

- Improve image generation quality, prompt adherence, and consistency

- Identify bottlenecks and failure modes across the pipeline

- Run experiments and A/B tests to measure improvements

Safety & Content Moderation

- Refine content safety systems for child-appropriate outputs, and develop new ones

- Build on our evaluation datasets for safety edge cases

- Analyze moderation performance and reduce false positives/negatives

- Stay current on best practices for AI safety in generative systems

Evaluation & Metrics

- Build evaluation frameworks to measure model performance at scale

- Define metrics that correlate with user satisfaction (aesthetic quality, relevance, safety)

- Develop automated evaluation pipelines (LLM-as-judge, CLIP scores, human eval)

- Track experiments and communicate findings to the team

Prompt Engineering

- Optimize prompts for transcription accuracy and image generation quality

- Develop systematic approaches to prompt testing and iteration

- Build prompt templates and guidelines for different use cases

Location: NYC only, On-site (flexible on WFH but we like to be in office the majority of the week) in our Brooklyn based office, close to most major train lines.

Salary Range: $150k - $250k base + equity and benefits