Testbook is one of India’s largest ed-tech platforms for competitive exam preparation. I was one of the first two data hires β joining as an analyst, and leaving as a senior data engineer who had built the entire data function, a revenue-generating CRM platform, and ML-powered product features.
Starting from zero: I set up Testbook’s first analytics infrastructure β Excel to Jupyter notebooks to live Redash dashboards pulling from MongoDB, BigQuery, and MySQL. These became the operating layer for product, content, and marketing teams. One early win: identifying a post-signup dropout rate of 50% and reducing it to 30% through data analysis and targeted interventions.
The CRM that became a revenue engine: What started as a two-person checkout recovery experiment evolved into a fully custom internal telesales platform. I designed the lead flow architecture, database model, real-time ingestion pipelines (Pub/Sub + Cloud Functions), lead scoring, and attribution strategy. At its peak, this platform contributed to 30% of Testbook’s revenue β built from scratch because nothing off-the-shelf fit the use case.
The T-Score moment: Indian Railways exams use a statistical normalisation method called T-Score to rank millions of aspirants. When a major exam was announced with weeks β not months β to prepare, we saw an opportunity. I built the automation pipeline to compute and deliver personalised T-Scores to every user who attempted our test series, using population-level aggregates decoupled from user-facing delivery. We were the only platform in India offering this at scale. The result: 60% of aspirants for that exam came to Testbook.
Other highlights:
- Built a question difficulty quantification algorithm using Apache Spark β reducing content curation time from months to days and improving educational quality at scale.
- Architected a CDC-based MongoDB consolidation pipeline using Airflow and GCS, saving 50+ dashboards and 1000+ queries from breaking during a critical database migration.
- Founded and scaled the data engineering department to a 4-person team.