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Sushant Nandwani

Senior Software Engineer at Kleinanzeigen · Berlin

I'm Sushant. I build AI-powered products end to end: Java services, the LLM layer, and the interface people actually touch.

01

About

I'm a senior full-stack engineer at Kleinanzeigen, one of Germany's largest online marketplaces. I work on the tools commercial sellers run their business on, and on the AI features and developer tooling behind them.

Most weeks are split between Spring Boot services and Astro and React frontends. I like owning a feature from the data model to the pixel, keeping architecture boring, and making pages fast.

Lately that means LLM features in production, agentic workflows for code review, and MCP tools that let AI assistants work with our real systems.

  1. Kurukshetra 2016 · BTech
  2. Bangalore 2021 · Capgemini
  3. Koblenz 2022 · MSc
  4. Berlin 2024 · Kleinanzeigen
02

Experience

  1. 2024 – Now

    Senior Software Engineer at Kleinanzeigen

    Berlin · previously Full Stack Engineer

    • Architected and led Business Hub, the new portal for commercial sellers, and owned the phased migration of 1M+ users onto it under live production constraints.
    • Moving features off the Java/Spring MVC monolith into a Spring Boot service with hexagonal architecture: REST endpoints, plus Feign, GraphQL and gRPC clients to downstream services.
    • Built a self-healing pull-request pipeline of three agentic workflows (review, suggest, fix), now a shared GitHub Action other teams are adopting.
    • Built an internal MCP server with 38 test-data tools, so engineers create test users, ads and accounts from Claude Code instead of an admin UI.
    • Ran A/B tests across freemium acquisition and onboarding, contributing to 30%+ year-over-year customer growth.
    • Maintained the shared design system and authored the Playwright end-to-end testing strategy adopted across teams; cut CI/CD time by 60%.
    • Java
    • Spring Boot
    • TypeScript
    • React
    • Astro
    • LLMs
    • MCP
  2. 2023 – 2024

    Full Stack Developer at Hintbox

    Koblenz

    • Owned large product initiatives end to end: architecture, implementation and launch.
    • Built a TypeScript and React frontend framework of modular components, lifting engagement by 20%.
    • Designed Django REST APIs that responded 30% faster, and automated test-data setup, cutting it by ~80%.
    • TypeScript
    • React
    • Django
  3. 2023

    Frontend Developer at Deloitte

    Germany

    • Built data-intensive interfaces for machine-learning analytics tools.
    • Refactored the component architecture for a 25% rendering performance gain.
    • React
    • Data visualisation
  4. 2021 – 2022

    Software Analyst at Capgemini

    Bangalore

    • Led the front-end modernisation of Amgen's global portal, from jQuery to React.
    • Performance work across React, Sitecore and Bootstrap made the portal 20% faster worldwide.
    • React
    • Sitecore

Education

  • 2024MSc Web and Data Science at University of Koblenz
  • 2020BTech Computer Science at Kurukshetra University
03

Skills

AI & LLMs
Claude API · Gemini · AWS Bedrock · AWS SageMaker · LLM evals · Tool calling & MCP · Agentic workflows · RAG & pgvector
Backend
Java · Spring Boot · Kotlin · Node.js · Python · REST · gRPC · GraphQL · SQL
Frontend
TypeScript · React · Astro · Next.js · Tailwind CSS · Design systems · D3.js · Web performance
Delivery
AWS · Docker · GitHub Actions · CI/CD · Playwright
Languages
English (fluent) · Hindi (native) · Punjabi (native) · German (A1)
04

Projects

  • job-scout (opens in a new tab)

    2026

    A job-search pipeline with Claude in four tool-less roles. It scans company job boards, screens every posting for text aimed at AI before a model reads it, scores fit with an explainable formula, and prepares a fact-checked CV for each strong match. It never applies on its own.

    TypeScript · Claude · SQLite · Docker

  • pr-review-agent (opens in a new tab)

    2026

    A GitHub Action that reviews pull requests with any OpenAI-compatible model. The model reads the diff and gets no tools, so it can comment but never change your code.

    TypeScript · GitHub Actions · Zero dependencies

  • Stilllight

    2025

    A photo gallery that publishes itself. Drop a photo in a folder and it is resized, stripped of GPS data and uploaded to Cloudflare R2, then appears on the site with no rebuild.

    Astro · Node.js · Cloudflare R2Source (opens in a new tab)
05

Writing

All writing New posts by feed: RSS

06

What I believe

  1. The boring decisions early on are why we move fast now. Not the framework choice.

    From “Building a commercial portal for Kleinanzeigen”

  2. AI is most useful when you give it context.

    From “Building a commercial portal for Kleinanzeigen”

  3. Legacy migration is unglamorous, and it's where all the user value ships.

    From “Building a commercial portal for Kleinanzeigen”

  4. AI review isn't replacing human review. It means the first human pass starts from a better place.

    From “AI code review on every pull request”

  5. Imagine your code as a bridge. Would you drive over it?

    Borrowed from Ines Akrap · From “Would you drive over your code?”

07

Outside work

  • Photography

    I photograph buildings and streets, mostly on a pocket-sized Sony RX100 VII. The photos live on Stilllight, a gallery I built that publishes itself.

    See the photos

  • Running

    I run most weeks, usually long, easy runs through Berlin, and I train for half marathons. I also ride, often indoors on Zwift.

  • In the room

    You'll find me at hackathons and conferences: START Hack in St. Gallen, performance.now() in Amsterdam, and volunteering at WeAreDevelopers.

    What I took from performance.now()

Say hello.

Email is the quickest way to reach me.

nandwanisushant@gmail.com

Prefer a terminal?curl iamsushant.dev/cv.txt

Need a CV? Print this page and it turns into one.

Asking an AI about me? Point it at iamsushant.dev/llms.txt.