WILLIAM SUN
Summary - Senior Software Engineer & AI Builder
AI-focused Software Engineer (8 yoe) who architected revenue-critical ad platforms powering $10B+ in annual spend, and shipped production LLM features end-to-end. Eager to go deeper on RAG pipelines, eval frameworks, and open-weight fine-tuning.
Recent (AI) Projects
- Therapy Bot (2025): LLM triage bot that classifies user messages and routes them to the best-fit modality (CBT, RO-DBT, somatic-mindfulness, growth-mindset coaching), swapping persona-specific system prompts on the fly
- AWS Cloud Resume (2025) - This site, deployed on AWS (Lambda, API Gateway, DynamoDB, CloudFront, IaC/Terraform)
- TrySniff.com, 2024 - LLM-driven dog food safety app that checks whether your leftovers are safe to share
- 90apps.info, 2024 - "90 AI apps in 90 days" challenge, focusing on rapid prototyping and real-world feedback.
Professional Experience
Los Angeles, CA
2019 – 2024
2019 – 2024
- Led a year-long, $10B+ integration of the Google Reach Planner into Display & Video 360 as technical lead, collaborating with 10+ senior cross functional stakeholders to set OKRs and coordinate resources.
- Drove E2E launch, including five bug bashes and stages, delivering $3.9B/quarter in planned ad revenue.
- Prototyped internal LLM tool to summarize large-scale forecasting data and automate report generation for stakeholders, integrating both structured and unstructured data.
- Redesigned account selection system to support 10m+ accounts/campaigns, 20+ filters, in-memory and server-side processing—reducing timeouts and latency.
- Partnered with a Zurich team to merge metrics and insights, leveraging data to inform product roadmaps.
- Architected and deployed Java microservices for multi-currency ad billing calculations, caching exchange rates to optimize performance.
Acorns
Fullstack Software Engineer
Irvine, CA
2017 – 2019
2017 – 2019
- Launched check deposit and money transfer features to 150k beta users, working with 6 teams to align roadmap.
- Rebuilt 15+ page React signup flow (signup.acorns.com) & improved test coverage 96%.
Education
Yale University
B.S. in Computer Science
New Haven, CT
2013 – 2017
2013 – 2017
Skills
- LLM / GenAI Tools: LangChain, OpenAI, LangGraph, RAG pipelines
- Languages: Python, Spark, SQL, Java, JavaScript/TypeScript
- Frameworks: React, Node.js, Next.js, Angular
- Cloud & Infra: GCP, AWS, Terraform, IaC, CI/CD, Serverless, CloudFront/CDN, Docker, Vercel, Supabase, PostgreSQL, Redis,
- Other: Cursor/Claude expert, prompt engineering, few-shot prompting, LLM routing