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Senior Backend Engineer - Ads ML System

Job in Toronto, Ontario, M5A, Canada
Listing for: Faire
Part Time, Per diem position
Listed on 2026-01-12
Job specializations:
  • IT/Tech
    Machine Learning/ ML Engineer, AI Engineer
Salary/Wage Range or Industry Benchmark: 156000 - 214500 CAD Yearly CAD 156000.00 214500.00 YEAR
Job Description & How to Apply Below

About this Role:

Faire’s Ads teams are building the next generation of marketplace intelligence — powering personalized discovery and efficient ad delivery for our brands and retailers. Our systems connect the right products with the right buyers through intelligent pricing, auction mechanisms, and large-scale retrieval and ranking pipelines.

As a Senior Backend Engineer, you’ll take ownership of the core algorithms and infrastructure that shape the way our ads and search systems decide what to show, to whom, and at what price. You’ll partner with Data Science and Infrastructure teams to design training workflows, deploy models, and operate low-latency inference services, owning the end-to-end model lifecycle (feature generation → training → evaluation → deployment → monitoring) for Ads retrieval, ranking, and pricing.

This role offers a rare opportunity to shape both product and technical direction in a fast-moving, high-impact area at Faire.

What You’ll Do:

  • Own critical services within our Kotlin-based backend, driving reliability, scalability, and low-latency performance across billions of ad and search events.
  • Design and evolve large-scaleretrieval, ranking, and pricing systems to optimize relevance, performance, and marketplace efficiency.
  • Develop auction-based delivery systems and scoring pipelines that balance advertiser ROI with retailer experience.
  • Collaborate cross-functionally with Data Science to prototype, evaluate, and productionize machine learning models and their training workflows.
  • Build and operate online inference services (e.g., feature access, real-time scoring, canary/shadow deploys) with clear latency and reliability SLOs.
  • Mentor engineers and contribute to team best practices in design reviews, performance tuning, and system architecture.
  • We’re Excited About You Because You Have:

  • Experience:

    5+ years in backend systems, including 2+ years in designing, deploying, and scaling ML inference and online serving systems.
  • Technical Depth:
    Proficiency in Kotlin, Java, or similar object-oriented languages; comfort with distributed systems, service design, and performance optimization.
  • ML Fluency:
    Hands-on experience with model training pipelines and operating production online inference/serving, including deploying models to real-time scoring paths on ads/search/ranking.
  • Collaboration:

    Strong communication skills and a track record of partnering with cross-functional stakeholders, from DS to PM, to deliver complex systems.
  • Mindset:
    Curiosity and a drive to understand complex market dynamics; passion for applying data and algorithms to real-world business problems.
  • Education:

    Bachelor’s degree in Computer Science/Engineering or equivalent industry experience.
  • Technologies We Use and Teach:

  • Kotlin, Java, Python
  • Snowflake, Airflow, Spark
  • Tensor Flow, PyTorch, AWS
  • Hugging Face Transformers, Pandas, Num Py
  • JUnit, Hibernate, Guice, Jersey
  • HTTP, JSON, Protocol Buffers
  • MySQL, Dynamodb, Cockroach

    DB, Elasticsearch
  • Salary Range:

    Canada: the pay range for this role is $156,000 - $214,500per year.

    This role will also be eligible for equity and benefits. Actual base pay will be determined based on permissible factors such as transferable skills, work experience, market demands, and primary work location. The base pay range provided is subject to change and may be modified in the future.

    Hybrid Faire employees currently go into the office 2 days per week on Tuesdays and Thursdays. Effective starting in January 2026, employees will be expected to go into the office on a third flex day of their choosing (Monday, Wednesday, or Friday). Additionally, hybrid in-office roles will have the flexibility to work remotely up to 4 weeks per year. Specific Workplace and Information Technology positions may require onsite attendance 5 days per week as will be indicated in the job posting.

    Applications for this position will be accepted for a minimum of 30 days from the posting date.

    Why you’ll love working at Faire

  • We are entrepreneurs:
    Faire is being built for entrepreneurs, by entrepreneurs. We believe entrepreneurship is a calling and our mission is to empower entrepreneurs to chase their dreams. Every member of our team is taking…
  • Position Requirements
    10+ Years work experience
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