David Grömling

Software engineer in Frankfurt. I make software do less work, and I'd like that to count for the climate.

Roots
What guides my choices
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Roots: what guides my choices

Teaching in Kigali

Rwanda · 2009 – 2010

Volunteered at the Maison des Jeunes de Kimisagara, teaching computer skills to 30 students.

theelternhub.com

Maintainer · 2025 – today

I build and maintain theelternhub.com, a bilingual English/Spanish site for parents.

Why green tech

The taproot

Most of my work has been about systems wasting less: idle warehouses switched off, dead code deleted, the same work on less hardware. I want that to count for more than a smaller bill.

Trunk: education

BSc Informationssystemtechnik

Technische Universität Darmstadt · 2011 – 2014

Electrical engineering and computer science in one degree: how hardware spends energy and how software spends hardware.

Exchange year

University of Illinois Urbana-Champaign · 2014 – 2015

A year of computer science in the US.

MSc Informationssystemtechnik

Technische Universität Darmstadt · 2015 – 2018

Networks, distributed systems and real-time computing.

Branches: roles

Research assistant

TU Darmstadt · 2016 – 2017

  • Built Linux kernel modules for real-time datacenter applications, with a 2 µs bound on packet processing
  • Co-authored the RideSense paper on ticketless public transport

Software engineer, Cisco

San Jose, CA · 2017 – 2018

  • Built the Network Assurance Engine, a new product, and contributed to its launch
  • Built Service Chain Support, Contract Preferred Group Support and Event Normalization
  • Made it 60% faster through profiling and better architecture

Software engineer, Cisco

Frankfurt · 2018 – 2021

  • Managed a team of four engineers spread across time zones: planning, standups, 1:1s
  • Led the UI migration from Angular to React
  • Merged the Network Insights and Assurance Engine products on one shared data model
  • Built the Compliance and Pre-Change Analysis features

Founding senior software engineer, Keebo

Frankfurt · 2021 – today

Keebo tunes cloud data warehouses automatically so they run with less waste.

  • Founding team member; helped land the first 10 paying customers within six months
  • Led the Databricks export pipeline (Airflow, BigQuery, savings estimation)
  • Interviewed and onboarded new hires

Keeping the platform healthy

Keebo · 200-module monorepo

  • Owned the CI/CD pipeline
  • Raised dependency remediation from 5% to 82%, with zero critical CVEs
  • Modernized Gradle, Spring Boot and Angular
  • Wrote the team's engineering standards and did 1,700+ code reviews

AI-assisted development

Keebo · team-wide

Introduced AI-assisted development across the team, and set the practices that keep generated code reviewable.

Apples: achievements

RideSense: Towards Ticketless Transportation

IEEE Vehicular Networking Conference · 2016

Co-authored research on making public transport ticketless and easier to use.

doi.org/10.1109/VNC.2016.7835965

60% faster

Cisco Network Assurance Engine · 2017

Increased performance by 60% through better software architecture and profiling: the same work on less hardware.

Query routing, >99% uptime

Keebo · Envoy and Go

Launched Keebo's query-routing product with more than 99% uptime: every query goes to the warehouse that can run it most cheaply.

Auto-suspend, patented

US Patent 11,693,857 B1 · 2023

Designed the optimization that switches warehouses off when nobody needs them. It drives the largest share of customer savings, and its guardrails added a further 2%.

Co-inventor with the company founders: “Managed tuning for data clouds”.

Making Data Clouds Smarter at Keebo

ACM SIGMOD ’23 · Industrial Track

Paper on automated warehouse optimization using data learning.

doi.org/10.1145/3555041.3589681

400,000+ lines of dead code removed

Keebo · platform health

Deleted more than 400,000 lines of dead code from a 200-module monorepo: less to build, test and ship on every change.

Next

The next branch

Open to new roles

I'm looking for software engineering roles in green tech: energy, grids, mobility, climate data. Anywhere that making systems run leaner means less carbon.