Senior Backend Engineer – Shopping Agents

Fusion AI Labs

. Own architecture, code, deployments, monitoring, and on-call for systems transacting around the clock .

Posted 9/24/2026full-timeRemote • GermanySeniorWebsite

Core Competencies

Role fit

Core Competencies

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Demonstrates expertise in building and operating backend and infrastructure systems with a strong focus on Python, observability, and production system ownership. Capable of developing AI-first products and addressing adversarial systems in a dynamic e-commerce environment.

Highest-signal resume keywords

Python ProgrammingProduction System OwnershipInfrastructure MonitoringAI-First Product DevelopmentE-Commerce Background

ATS Keywords

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Hard Skills

Backend DevelopmentInfrastructure SystemsDatabase ManagementObservabilityMachine LearningDeep LearningEmbedding-Based RetrievalLLM Query UnderstandingRerankingCaching

Soft Skills

Problem SolvingAdaptabilityAttention to Detail

Industry Keywords

E-CommercePaymentsFraud InfrastructureRisk Infrastructure

Tech Stack

Tools & technologies

Python

About the role

Key responsibilities & impact

Own architecture, code, deployments, monitoring, and on-call for systems transacting around the clock
Build and operate checkout agents that drive live checkouts at scale
Make checkout-agent failures rare and recovery automatic across changing retailer systems
Scale product ingestion from hundreds of sources to thousands using self-generating, self-validating, and self-monitoring infrastructure
Develop search and ranking systems using embedding-based retrieval, LLM query understanding, reranking, and caching
Work directly with the CTO

Requirements

What you’ll need

5+ years building backend and infrastructure systems, with strong Python
Experience owning production systems end to end, including deploys, databases, observability, and on-call responsibilities
Ability to address adversarial systems and failure modes
Strong focus on correctness for systems handling real customer payments
Ability to work without a finished specification in a small, changing environment
Experience building AI-first products or LLM-based agents in production (nice to have)
Working knowledge of classic ML and deep learning for retrieval and ranking (nice to have)
Background in e-commerce, payments, or fraud and risk infrastructure (nice to have)