Quizlet

Sr Backend Engineer

Quizlet$130K — $180K *
Information Technology
Less than 5 years of experience
Job Overview by Ladders

Qualifications

  • 4+ years of experience in backend or data engineering with ownership of production data pipelines/services
  • Proficiency in Python (or Java/Scala) for development; familiarity with orchestration tools like Airflow
  • Hands-on experience with Elasticsearch/OpenSearch production environments
  • Strong SQL skills and experience with data warehouses (e.g. Snowflake, BigQuery)
  • Experience designing and operating APIs for low-latency systems
  • Comfort with cloud infrastructure operations (AWS/GCP/Azure) and cost-performance analysis

Responsibilities

  • Design and maintain data pipelines for ingestion and indexing in Elasticsearch at scale
  • Own index design, including mappings, sharding, and lifecycle management
  • Build and operate infrastructure for hybrid search retrieval combining lexical and vector similarity
  • Integrate embedding generation into pipelines using hosted or open-source models
  • Monitor cluster health, service latency, and drive performance improvements
  • Implement zero-downtime reindexing strategies for schema and data evolution
  • Collaborate with internal teams to optimize cluster sizing and cost

Benefits

  • Encouraged work-life balance with collaboration on managing workloads
  • 20 vacation days provided and expected to be utilized
  • 100% employee health, dental, and vision insurance coverage
  • 401k plan with employer matching
  • Access to professional development resources like LinkedIn Learning
  • Paid Family Leave and wellness benefits available
  • Annual paid time off for participating in volunteer programs
Full Job Description
About the Team:

The Search team (part of Coach & Orchestration) owns the full path from raw content to search results - the pipelines and infrastructure that get content indexed, the services that query it, and the systems that serve it with high relevance and low latency. We're looking for a Backend Engineer who can own this end-to-end: from data ingestion and Elasticsearch index design through the retrieval/query services that power search in production.

You'll bring strong backend and data engineering fundamentals - pipeline design, orchestration, data modeling, and service/API development - with enough exposure to embeddings, vector search, and ML-adjacent concepts to support our hybrid (lexical + vector) retrieval today and our move toward ranking and relevance improvements tomorrow. You'll work at the intersection of data infrastructure, backend services, and search, ensuring our indices are fresh and our retrieval services are performant, reliable, and built to support increasingly sophisticated search.

About the Role:

To support collaboration, we ask employees to be in the office at least two days a week: Wednesday and Thursday.

In this role, you will:
  • Design, build, and maintain data pipelines that ingest, transform, and load content into Elasticsearch indices at scale.
  • Own index design - mappings, analyzers, sharding strategy, and lifecycle management - balancing indexing throughput, query latency, and storage cost.
  • Build and operate the infrastructure for hybrid retrieval, combining lexical (BM25) search with dense vector similarity (kNN/HNSW) in Elasticsearch.
  • Design and maintain the backend retrieval/query services that sit in front of Elasticsearch - API design, request routing, caching, and query fan-out.
  • Integrate embedding generation into pipelines - batching, caching, and re-embedding workflows when models or content change - using off-the-shelf or hosted embedding models.
  • Partner with product and applied ML teams to support the evolution from retrieval into multi-stage ranking, including feeding features to future learning-to-rank systems.
  • Monitor and troubleshoot cluster health, service latency, indexing throughput, and query performance; drive improvements in reliability and observability.
  • Implement zero-downtime reindexing and index cutover strategies (aliasing, blue/green indices) to support continuous schema and data evolution.
  • Establish data quality and validation practices to catch pipeline failures and indexing issues before they reach production.
  • Collaborate with infrastructure/platform teams on cluster sizing, service scaling, and cost optimization.
  • Support experiment rollout for retrieval and ranking changes, working with feature flagging or A/B test infrastructure.
  • Stay current on Elasticsearch/OpenSearch and retrieval-infrastructure best practices, evaluating what's worth adopting.
What you bring to the table:
  • Minimum 4+ years of experience in backend or data engineering, with hands-on ownership of production data pipelines and/or backend services.
  • Strong SQL and experience with data warehouses (Snowflake, BigQuery, Redshift, or similar).
  • Proficiency in Python (or Java/Scala) for pipeline and service development, and experience with orchestration tools (Airflow, Dagster, Prefect, or similar).
  • Experience with dbt for data transformation, modeling, and testing within the warehouse.
  • Hands-on experience with Elasticsearch or OpenSearch in production - index design, mappings, ILM, sharding, and cluster tuning.
  • Experience designing and operating backend services/APIs (REST or gRPC) - request handling, caching, and performance optimization for low-latency, read-heavy systems.
  • Experience with service observability - tracing, metrics, and alerting (Datadog, Prometheus/Grafana, or similar).
  • Comfort with containerization and deployment (Docker, Kubernetes) for production services.
  • Clear, effective communication, with the ability to collaborate well with data scientists, ML engineers, and product partners.
  • Comfort operating in cloud infrastructure (AWS/GCP/Azure), including cost and performance tradeoffs for search infrastructure.
Bonus points if you have:
  • Experience with batch and/or streaming data processing (Spark, Kafka, Flink, or similar).
  • Practical experience with vector search - dense_vector fields, kNN/HNSW, and combining lexical and vector scores for hybrid retrieval.
  • Working familiarity with embedding models (open-source or hosted/API-based) - generating, storing, versioning, and refreshing embeddings at scale.
  • Understanding of retrieval evaluation basics (recall@k, NDCG, MRR).
  • Experience with learning-to-rank libraries (e.g., LightGBM, XGBoost rankers) or exposure to reranking pipelines.
  • Experience with reciprocal rank fusion (RRF) or other hybrid score-blending techniques.
  • Familiarity with vector databases beyond Elasticsearch (FAISS, ScaNN, pgvector, etc.).
  • Prior experience scaling search/retrieval infrastructure in a high-traffic consumer or enterprise product.
Compensation, Benefits & Perks:
  • Collaborate with your manager and team to create a healthy work-life balance
  • 20 vacation days that we expect you to take!
  • Competitive health, dental, and vision insurance (100% employee and 75% dependent PPO, Dental, VSP Choice)
  • Employer-sponsored 401k plan with company match
  • Access to LinkedIn Learning and other resources to support professional growth
  • Paid Family Leave, FSA, HSA, Commuter benefits, and Wellness benefits
  • 40 hours of annual paid time off to participate in volunteer programs of choice

About Quizlet

Quizlet is an online learning platform that provides study tools for students. The company was founded in 2005 by Andrew Sutherland and is based in San Francisco, California. Quizlet's platform allows users to create and share study materials, such as flashcards and quizzes, and offers a variety of study modes to help users learn and retain information. The company has over 50 million active users and has raised over $60 million in funding.
Learn more about Quizlet
Size
200 employees
Industry
Founded
2007

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