Senior Backend Engineer, Shopping Agents

Fusion AI Labs

. Own checkout agents: architecture, coding, 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 infrastructure systems with a strong focus on Python, observability, and production system ownership. Capable of developing resilient systems that handle variability and ensure correctness in payment processing.

Highest-signal resume keywords

Backend System DevelopmentPython ProgrammingProduction System OwnershipInfrastructure ScalabilityAI-First Product Experience

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Hard Skills

Backend DevelopmentInfrastructure SystemsPythonDatabase ManagementObservabilityProduction DeploymentsError ResolutionEmbedding-Based RetrievalLLM Query UnderstandingReranking

Soft Skills

Problem SolvingAdaptabilityAttention to Detail

Industry Keywords

E-CommercePaymentsFraud InfrastructureRisk InfrastructureMachine LearningDeep Learning

Tech Stack

Tools & technologies

Python

About the role

Key responsibilities & impact

Own checkout agents: architecture, coding, deployments, monitoring, and on-call for systems transacting around the clock
Build and operate frontier-model computer-use agents driving live checkouts at scale
Develop infrastructure that handles retailer variability and enables rare failure and automatic recovery
Scale product ingestion from hundreds of sources to thousands
Build infrastructure that generates, validates, and monitors itself
Implement search and ranking 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 resolve underlying classes of production problems rather than only individual incidents
Ability to work on adversarial systems where external factors actively create challenges
Strong focus on correctness for systems handling customer payments
Ability to work without a finished specification in a rapidly changing environment
Nice to have: production experience building AI-first products or LLM-based agents
Nice to have: working knowledge of classic machine learning and deep learning, including retrieval and ranking
Nice to have: background in e-commerce, payments, or fraud and risk infrastructure