Senior Backend Engineer, Shopping Agents

Fusion AI Labs

. Own architecture, code, deploys, monitoring, and on-call for systems that transact around the clock .

Posted 10/19/2026full-timeRemote • PolandSeniorWebsite

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 programming and production system ownership. Capable of developing advanced search and ranking systems while ensuring correctness in payment handling and adapting to evolving requirements.

Highest-signal resume keywords

Python ProgrammingProduction System OwnershipInfrastructure DevelopmentSearch And Ranking SystemsE-Commerce Background

ATS Keywords

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Applicant Tracking System Keywords

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Hard Skills

Backend DevelopmentInfrastructure SystemsObservabilityDatabase ManagementAI-First Product DevelopmentMachine LearningDeep LearningEmbedding-Based RetrievalLLM Query UnderstandingReranking

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, deploys, monitoring, and on-call for systems that transact around the clock
Build and operate checkout agents using frontier-model computer-use agents driving 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
Build infrastructure that generates, validates, and monitors product ingestion
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
Strong Python skills
Experience owning production systems end to end, including deploys, databases, observability, and on-call
Ability to address systemic causes rather than isolated incidents
Ability to work on adversarial systems
Strong focus on correctness for systems handling customer payments
Ability to work without a finished specification in a changing roadmap
Nice to have: experience building AI-first products or LLM-based agents in production
Nice to have: working knowledge of classic machine learning and deep learning
Nice to have: background in e-commerce, payments, or fraud and risk infrastructure

Benefits

Comp & perks

Remote work arrangement
Full-time employment