Portrait of Bennett Hollstein

Bennett Hollstein

@vantezzen

Fullstack Product Engineer focused on thoughtful products, robust systems, and practical AI.

Berlin, Germany

Selected projects

Quick wins for my ROAS?
get_campaign_metrics

WaveMetrics Sidekick

AI teammate for Google Ads accounts

  • Vercel Eve
  • MCP
  • LangFuse
  • Multi-agent
Fresnel

Fresnel

Virtual relighting on macOS

  • SwiftUI
  • CoreML
  • Metal
  • AI
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Name
Agree

autoform

Instant React form for your schema

  • 230k+ monthly downloads
  • 3.5k GitHub stars
  • TypeScript

Wrapped for TikTok

Year-in-review for TikTok

  • 10M peak monthly users
  • NextJS

Work experience

Fullstack DeveloperatSmarketer

Oct 2025 – Present · 11mo

Build AI-native product features and agent workflows using TypeScript, Python and modern LLM tooling, including subagents, MCP integrations, memory and durable execution across Next.js, Django/Laravel, PostgreSQL, Redis, AWS and Vercel

Working Student Fullstack DeveloperatSmarketer

May 2020 – Sep 2025 · 5yr 4mo

Helped develop a scalable conversion measurement and attribution platform, including asynchronous processing and AWS-based ingestion infrastructure

Education

M.Sc. Applied Computer ScienceatHTW Berlin

2023 – 2025 · Final grade 1.3

Master thesis on object placement in Augmented Reality

B.Sc. Applied Computer ScienceatHTW Berlin

2019 – 2022 · Final grade 1.28, magna cum laude

Bachelor thesis on optimizing web applications for Google’s Core Web Vitals

Let’s talk

You can reach me via email at

hello@vantezzen.io