
Ranjana Rajendran
Verified Expert in Engineering
Software Engineer and Developer
Seattle, WA, United States
Toptal member since May 7, 2026
Ranjana is a software engineer with 10+ years of experience building production ML infrastructure at Amazon Web Services (AWS) and Mastercard. She has a strong background in MLOps, distributed systems, and scaling ML pipelines. She has focused on LLM deployment, retrieval systems, and model serving, continuously applying rigorous engineering to real-world AI systems.
Portfolio
Experience
- Linux - 20 years
- Java - 20 years
- Cloud - 20 years
- DevOps - 20 years
- Python - 20 years
- Distributed Systems - 10 years
- Machine Learning Operations (MLOps) - 10 years
- Big Data - 10 years
Preferred Environment
Machine Learning, Machine Learning Operations (MLOps), Big Data, Distributed Systems, Data Processing, Spark, Hadoop, MapReduce, Cloud, DevOps, Amazon EC2, EMR, ECS, MySQL, PostgreSQL, SQLite, Oracle, Python, Java, C, C++, Scala, Flask, Spring, REST APIs, Streamlit, Plotly, Dash, Matplotlib, Tableau, Kerberos, Sentry, JSON Web Tokens (JWT), OAuth 2, Git, Visual Studio
The most amazing...
...projects I've undertaken as a software engineer involved building ML infrastructure at AWS and Mastercard.
Work Experience
Lead Software Engineer
Mastercard
- Engineered PII suppression and identity workflow systems powering ML-based fraud scoring for enterprise customers, ensuring compliance with privacy regulations while maintaining less than 100-milliseconds latency.
- Built distributed ETL pipelines processing terabytes of identity data using Spark on Databricks and EMR, orchestrated via Apache Airflow, with automated data quality checks and observability dashboards.
- Designed and managed a Redis-backed identity graph with 50+ million entities, enabling real-time ML fraud scoring with dynamic suppression and stateful updates.
- Co-invented a patented fraud detection system integrating multi-signal reasoning and real-time anomaly detection with production ML pipelines.
System Development Engineer
Amazon Web Services (AWS)
- Owned monthly build and release cycles for Amazon Elastic MapReduce (EMR), maintaining 99.9% service up-time across ML and big data frameworks. Developed automated Java-based deployment tools, reducing release time by 40%.
- Built and maintained an integration testing framework with 200+ automated tests covering all EMR applications, reducing release-blocking bugs by 60% and ensuring reliability for downstream ML pipelines.
- Resolved 100+ critical integration issues between ML frameworks and the underlying operating system, reducing customer-impacting incidents by 40%.
- Designed and integrated new Amazon EC2 compute types (GPU instances, Graviton processors) and applications into EMR, enabling distributed deep learning training and improving ML workload performance by up to 50%.
- Participated in 24/7 on-call rotation, triaging and resolving production incidents for ML and big data workloads, maintaining high service availability for enterprise customers.
- Authored technical documentation and collaborated with product managers to launch new EMR features, directly supporting data scientists and ML engineers at Fortune 500 companies.
Senior Developer Support Engineer
Qubole
- Optimized large-scale data and feature engineering pipelines on Qubole’s Hadoop-as-a-service platform using MapReduce, Spark, Apache Hive, and Spark SQL.
- Enabled downstream ML model training and analytics through scalable distributed data processing pipelines.
- Improved pipeline runtimes by up to 70%, accelerating large-scale data processing and ML workflows.
- Reduced pipeline failures by 90%, increasing reliability and operational stability of ML data pipelines.
- Collaborated with engineering and product teams to enhance platform capabilities based on real-world ML and data science challenges.
Hadoop Engineer
Altiscale
- Troubleshot and optimized customer Apache Hive, Spark, and Spark SQL applications, achieving up to 50% query performance improvements through partition tuning, memory configuration, and query plan optimization.
- Performed Java performance and memory profiling using Eclipse Memory Analyzer to diagnose and resolve OOM errors and bottlenecks in production.
- Translated customer ML pipeline requirements into product feature requests and authored 20+ knowledge-base articles documenting best practices for big data and ML workloads.
- Configured and troubleshot Kerberos authentication and security in multi-tenant Hadoop environments, ensuring secure access control for enterprise customers.
Solutions Architect
Cloudera
- Deployed and managed CDH clusters (up to 45 nodes) on Amazon EC2 and private cloud infrastructure, supporting enterprise customers running large-scale ML training pipelines and data analytics workloads processing hundreds of terabytes.
- Configured the MySQL back end with master-slave replication for Cloudera Manager and CDH metadata services, ensuring high availability and fault tolerance for cluster management infrastructure.
- Architected Kerberos authentication for CDH with multiple integration patterns: local KDC with backup KDC, one-way cross-realm trust to Active Directory, and direct AD integration for enterprise SSO.
- Designed and implemented batch and real-time data pipelines using Spark, Hive, and Impala on HDFS, enabling automated data ingestion and transformation for ML model training with 99.5% SLA adherence.
- Integrated real-time data sources using Flume and RDBMS ingestion via Sqoop, building data warehouses supporting continuous ML model retraining for enterprise customers.
- Automated end-to-end ML pipeline orchestration using Oozie with integrated monitoring (Tableau dashboards), reducing pipeline failures by 40% and enabling self-service analytics for data science teams.
- Implemented role-based access control (Sentry) for secure multi-tenant access to Hadoop resources.
Experience
Technical Stack Advisor
https://ranjanarajendran.github.io/tech-stack-advisor/ML Model Serving Protocol Comparison
https://ranjanarajendran.github.io/ml-serving-comparison/Group Emotion Detection
https://ranjanarajendran.github.io/ml-projects/Group_Emotion_Recognition_description.htmlSpoiler Alert: NLP Classification
https://ranjanarajendran.github.io/ml-projects/Spoiler_Alert_NLP_Ranjana_Rajendran_description.htmlVolcano Eruption Prediction
https://ranjanarajendran.github.io/ml-projects/Volcano_ML_project_description.htmlFacebook Social Network Clustering
https://ranjanarajendran.github.io/ml-projects/FacebookClusters_RanjanaRajendran_description.htmlEducation
Master's Degree in Computer Science
University of California Santa Cruz - Santa Cruz, California, USA
Bachelor's Degree in Computer Engineering
Cochin University of Science and Technology - Kochi, India
Certifications
Cloudera Certified Specialist in Apache HBase
Cloudera
Cloudera Certified Developer for Apache Hadoop
Cloudera
Skills
Libraries/APIs
REST APIs, Matplotlib, PyTorch
Tools
Claude, Plotly, Tableau, Sentry, Git, Visual Studio, Apache Airflow, Amazon Elastic MapReduce (EMR), Spark SQL, Eclipse Memory Analyzer, Apache Sqoop
Languages
Python 3, Java, Python, SQL, C, C++, Scala
Frameworks
LangGraph, Spark, Hadoop, Flask, Spring, Streamlit, JSON Web Tokens (JWT), OAuth 2, Apache Spark
Paradigms
DevOps, Model Context Protocol (MCP), MapReduce
Platforms
Linux, Amazon EC2, Oracle, Databricks, Kubernetes
Storage
MySQL, PostgreSQL, SQLite, Apache Hive
Other
Distributed Systems, Machine Learning, Machine Learning Operations (MLOps), Big Data, Cloud, Prompt Engineering, Retrieval-augmented Generation (RAG), Agentic RAG Systems, RAG Pipelines, Vector Databases, LangChain, Agentic AI, Large Language Models (LLMs), Artificial Intelligence (AI), Model Monitoring, Model Evaluation, Model Tuning, Statistical Modeling, Data Processing, EMR, ECS, Dash, Kerberos, Computer Science, Computer Engineering, MLflow, A/B Testing, Qdrant, Model Deployment, CI/CD Pipelines
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