# Raj Chhapariya — AI / Data Engineer

> Personal portfolio and project case studies for Raj Chhapariya, an AI / Data Engineer based in Bengaluru, India.

AI / Data Engineer building data and LLM systems, evaluated RAG pipelines, in-process analytics with DuckDB, and web and mobile products. Open to projects, collaborations and AI / Data Engineering roles.

## Core Pages
- [Homepage](https://rajchhapariya.space/): Overview of featured projects.
- [About](https://rajchhapariya.space/about): Background, approach and experience.
- [Projects](https://rajchhapariya.space/projects): Case studies and products.
- [Resume](https://rajchhapariya.space/resume): Experience, education, skills and PDF downloads.
- [Full LLM Context](https://rajchhapariya.space/llms-full.txt): Longer project descriptions with the figures and their sample sizes.

## Case Studies
- [Agentic RAG Knowledge Assistant](https://rajchhapariya.space/projects/agentic-rag-assistant): RAG pipeline that audits its evidence before answering. On a 32-question held-out test set (from a 40-question dataset: 8 development, 32 held-out; test set of 24 answerable, 4 unanswerable and 4 false-premise questions) it had 0 of 4 hallucinations on unanswerable questions (hybrid baseline: 4 of 4), but lower accuracy on the 24 answerable ones (45.8% vs 60.4%) and about 17.7 s latency vs 1.86 s. Frozen results from before later auditor fixes; small samples.
- [AI Data Analyst Agent](https://rajchhapariya.space/projects/ai-data-analyst): Data analysis agent with four fixed tools, SQL restricted to single SELECT/WITH statements by regex keyword guardrails (35 blocked keywords) on an in-memory DuckDB connection, and a numeric check on its answers. 20-question benchmark.
- [Resume Roaster](https://rajchhapariya.space/projects/resume-roaster): Live resume analysis and rewriting product built with Next.js 16, Supabase and the OpenAI API. Founder & Independent Developer.
- [JanDarshan](https://rajchhapariya.space/projects/satta-darshan): Independent, open-source civic information platform for India with a 3D parliament view. Live at https://jan-darshan.vercel.app.

## Other Projects
- [Truly](https://trulyapp.online/): Social platform built around structured 60-minute video circles. Founder & Developer, since April 2026.
- [Namma Metro Guide](https://play.google.com/store/apps/details?id=com.rajch.nammametroguide): Unofficial Bengaluru Metro guide for Android, published on Google Play, built solo.
- [VyaparStack](https://vyaparstack-nine.vercel.app/): GST invoicing web application.
- MandateStack: B2B subscription billing platform (Jul 2026, private).

## Writing
- [Hybrid Retrieval Systems in Production](https://rajchhapariya.space/blog/hybrid-retrieval-bm25-dense-embeddings-rrf): BM25, dense retrieval and Reciprocal Rank Fusion, with a worked RRF example.
- [Deterministic Guardrails for LLM Agents](https://rajchhapariya.space/blog/deterministic-guardrails-sql-pydantic-llm-agents): fixed tools, SQL keyword filtering versus AST parsing, and the limits of each.
- [In-Process Columnar OLAP with DuckDB](https://rajchhapariya.space/blog/in-process-columnar-olap-duckdb-architecture): columnar storage, vectorized execution and when an in-process engine fits.
- [Next.js 16 App Router Architecture](https://rajchhapariya.space/blog/nextjs-16-app-router-server-components-ssr): Server and Client Components, serialization, streaming and static regeneration.
- [Evaluating Hallucination and Citation Faithfulness in RAG](https://rajchhapariya.space/blog/evaluating-hallucination-citation-faithfulness-rag): evaluation metrics, a citation-structure check and offline testing.

## Links
- [GitHub Profile](https://github.com/Rajchhapariya): Source repositories.
- [LinkedIn Profile](https://www.linkedin.com/in/rajchhapariya/): Professional background.
- [X / Twitter](https://x.com/raj_chhapariya)
- [Resume PDF](https://rajchhapariya.space/resume-enhanced.pdf): Two-page resume.
- [Sitemap XML](https://rajchhapariya.space/sitemap.xml)