Founding Engineer · Certus AI (Y Combinator S25)

Robert
Vetter

I'm Robert, studying IT-Systems Engineering at the Hasso Plattner Institute. Right now I'm a founding engineer at Certus AI in San Francisco, building voice AI that answers the phone for restaurants.

Before that: research at Fraunhofer, a semester at Berkeley, and a lot of programming competitions.

Portrait of Robert Vetter
Berlin · San Francisco
01

About

I grew up in Erfurt and spent most of school doing competitions: informatics, physics, maths. I wasn't especially good at any of them to begin with. I just kept going after most people stopped, and that turned out to be the main thing.

In years 11 and 12 two friends and I worked on a research project with Fraunhofer IIS, teaching a small neural network to pick the right clustering algorithm for a dataset. Two years of work, and the first problem I'd had where nobody could tell me the answer.

These days I write code at a startup whose customers are small, mostly family-run restaurants. If our system drops a call, someone loses an order that day. It's a good kind of pressure to work under.

Languages

  • German Native
  • English C1, Cambridge Advanced
  • Latin Latinum

Interested in

  • LLM systems
  • Algorithms
  • Quantitative finance
  • Energy markets

Away from the screen

  • Chess
  • Piano since 2012
  • Swimming
  • Reading

Tools I reach for

Languages
PythonTypeScriptJavaScriptJavaC++CSQLBash
AI / ML
LLM systemsRAG & retrievalFine-tuningReinforcement learningPyTorchscikit-learnNumPyPandas
Web & infra
Next.jsReactNode.jsPostgreSQL / SupabaseDockerGitLinuxGCPVercel
02

Experience

Certus AIY Combinator S25

since Oct 2025

Founding Engineer, San Francisco / remote

  • I built the onboarding system that turns a new restaurant into a working voice agent in about an hour. It used to take the founders days of manual setup. The pipeline assembles an agent out of roughly twenty smaller ones (ordering, reservations, catering, FAQs) and then does everything around it: buying the phone number, the database, the knowledge base, billing, going live.
  • We went from around 20 restaurants to over 150 in that time, and every new sale can now go live the same day.
  • I also own the ordering engine, which is an LLM for understanding what people say and a state machine for everything that has to be correct, plus the menu ingestion and validation stack behind it.
  • The dashboard restaurants use to run their service is mine too: call logs, what callers actually wanted, order insights, and the settings they change themselves.
  • I report to the CEO and sit in on product and pricing calls. A few things in production started as something I heard on a customer call and just went and built.
Voice AINext.jsSupabaseLLM systems

Bundesliga AI HackathonDFL, AWS and EintrachtTech

Apr 2025

Challenge winner, Frankfurt

  • Three of us won the chatbot challenge for the official Bundesliga app with a prototype that actually ran on both platforms by the end of the weekend.
  • Our concepts went into Captain, the feature that shipped in the app in 2026, and we were brought into the design work for it.
LLMPrototyping

Fraunhofer SCAIAlgorithms and Scientific Computing

Aug 2024

Research intern, computational finance, Sankt Augustin

  • A month on reinforcement learning for portfolio optimisation. I implemented PPO and DQN agents and benchmarked them against classical Markowitz mean-variance portfolios on historical equity data.
  • Mostly I learned how easy it is to build a backtest that lies to you. I took the NYIF course on machine learning for trading alongside it.
Reinforcement learningPythonBacktesting

Jane Streetinvite only

Oct 2024

Quantitative Trading Camp, London

  • A few days in London with a small group of STEM students from Germany and Switzerland. Probability, market microstructure, and a lot of mock trading against each other.
ProbabilityMarket microstructure

Fraunhofer IISschool research project

2022 to 2024

Research contributor, Nuremberg

  • The two-year research project I did in school, supervised by Fraunhofer IIS. We taught a small neural network to look at a dataset and pick which clustering algorithm to use, a decision people normally make by hand. I coordinated the three of us.
  • It won the Fraunhofer IDMT special prize at Jugend forscht, the Albert Schweitzer school prize and first place in the Inverso Software Challenge. I wrote it up publicly afterwards.
Neural networksClusteringResearch
03

Projects

Most of what I write day to day is in private company repos, so this is the public half.

Tessera

2026

An evidence layer for AI agents

Every claim the agent makes has to point back to the exact record it came from, and anything it can't prove it refuses instead of guessing. Actions get previewed and need a human to approve them, and you get a receipt you can check offline. There's a second verifier written from scratch in JavaScript to keep the first one honest, and a proof over 461,544 enumerated states that a PASS really does mean the decision was clean.

Source Live demo
PythonMCPCryptography

eao-rl

2026

Reinforcement learning for grid batteries

An agent that decides when to charge and discharge a grid battery on real German day-ahead power prices, without being allowed to see the future. I benchmarked it against a perfect-foresight optimiser, which is the most any strategy could ever make, and against the rolling-intrinsic strategy the industry actually uses. The result is one number: how much of the achievable profit it captured. Built on Fraunhofer SCAI's open source EAO framework.

Source
Reinforcement learningEnergy marketsPython

Automated clustering selection

2022 to 2024

The Fraunhofer IIS project

A pipeline that boils any 2D dataset down to ten geometric and statistical features, and a small network that maps those to the best clustering algorithm out of K-Means, DBSCAN, OPTICS and GMM. The point was to automate a choice that analysts normally make by eye.

Source Write-up
Neural networksPython

Older things

  • IOI solutions

    2023

    My solutions from the German qualification rounds for the International Olympiad in Informatics.

  • Stock price prediction

    2023

    Next-day price forecasting with an LSTM, plus the data pipeline behind stock-prediction.rvetter.com. This is the project that got me into machine learning, and it works about as well as that sounds.

  • ANPR

    2023

    Plate detection with a neural net, then OCR on the crop. End to end from photo to string.

  • Two Android apps

    2019 to 2021

    One identifies food, animals and flowers from the camera, on device. The other is a reflex game I wrote when I was 14 and it is exactly as sophisticated as that suggests.

  • OweFlow

    2024

    A Flutter app, written because keeping track of who owes what in a group chat never once worked.

04

Education

Hasso-Plattner-Institut, University of Potsdam

2024 to 2027

B.Sc. IT-Systems Engineering

  • Currently at a 1.4 average. The courses I've enjoyed most are software architecture, algorithms and machine learning.
  • HPI takes roughly 15% of applicants, which I only mention because people outside Germany usually ask.

University of California, Berkeley

Aug to Dec 2025

Semester abroad

  • Efficient Algorithms and Intractable Problems, Computability and Complexity, and a course on economic models.
  • I lived in a co-op where everyone volunteers a day a month, which is how I ended up handing out soup in Oakland. I also helped run the German Evening at the International House.

Albert-Schweitzer-Gymnasium, Erfurt

2020 to 2024

Abitur, 0.76

  • Best in my year and in the top ten in Thuringia.
  • I was in the maths and science specialist section, which had its own entrance exam, and got pulled into the physics centre of excellence a bit later.
05

Awards

since 2025

  • Dr. Friedrich Jungheinrich Foundation scholarship

    One of three picked from a bit over 200 applicants.

since 2024

  • Deutschlandstipendium

    Funded by SAP at HPI.

  • Friedrich Naumann Foundation for Freedom

    Merit scholarship.

  • e-fellows.net

    Online scholarship and network.

2023, 2024

  • Bundeswettbewerb Informatik

    Second and third prize in round two of the national computer science competition.

2023

  • Informatics olympiad, German qualification

    15th of the national top 60. The best four go to the IOI.

2021 to 2024

  • Physics olympiad

    Round two of the German selection, several years running.

  • Bundesweiter Physikwettbewerb

    National round in 2022.

  • Maths and physics olympiads, Thuringia

    State rounds across several years.

2024

  • Albert Schweitzer school prize

    For maths and computer science.

  • Inverso Software Challenge

    First place, which came with a spot in their mentoring programme.

  • Jugend forscht

    Fraunhofer IDMT special prize.

06

Volunteering

Tutoring in Erfurt

since 2022

A few afternoons a week I tutor kids who didn't grow up in Germany, in a refugee accommodation next to the federal labour court. Maths, physics and German. A school friend of mine lives there, which is how I got involved. Several of them are at Gymnasium now.

Looking after my grandparents

since 2018

Both of them have blood cancer. Since year 10 I've been helping out a few times a week: shopping, doctor's appointments, the everyday things.

Marking at the Thuringian maths and physics olympiad

since 2020

A few times a year at the state round. It's the competition that got me started, so it seemed like the least I could do.

Berkeley and Oakland

2025

My co-op ran a monthly volunteering day. We set up a supply tent at a homeless outreach in Oakland and handed out soup. Some of the people who came through had studied, some had run their own companies.

Swimming club and parish

ongoing

I've been at the Erfurt swimming club since I was small and now help at meets and coach the younger groups. At my parish in Erfurt-Süd we ran a fundraiser for kids in the region and collected a bit over 1,000 euros.

07

Contact

If you want to talk about something here, or work on something together, just send me an email.

Email
robert-vetter@gmx.net
University
robert.vetter@student.hpi.uni-potsdam.de

Hasso-Plattner-Institut, University of Potsdam

GitHub
github.com/robert-vetter
LinkedIn
robert-vetter-erfurt
Based in
Berlin · San Francisco