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RAGLens: a study on understanding, evaluating, and comparing retrieval-augmented generation techniques (2nd Gen)

Kit Ho Chan

DR-NTU (Nanyang Technological University), 2026

28 participants

Abstract

Retrieval-Augmented Generation (RAG) has become a core building block of modern large language model applications, yet there is no one-size-fits-all solution, the effectiveness of different pipeline configurations varies across datasets, domains, and query types. Most existing research focuses on introducing new techniques and reporting benchmark performance, leaving a gap in practical tooling that supports developers in navigating, comparing, and understanding these choices. This project presents RAGLens (Gen-2), a cloud-deployed, developer-centred platform for exploring, comparing, and evaluating RAG pipelines. Building on the first-generation prototype, this second-generation system addresses three key limitations: limited accessibility, the absence of formal user evaluation, and insufficient support for emerging techniques. RAGLens (Gen-2) supports nine RAG techniques across pre-retrieval, retrieval, and post-retrieval stages, providing a learning-oriented interface with technique-specific explorer pages, step-by-step execution traces, side-by-side comparison with automated G-Eval scoring and Meta-LLM recommendation, and benchmark evaluation using RAGAS. To ground the system in real developer needs, a structured developer survey was conducted with 25 respondents spanning varying roles and experience levels. Findings revealed that current RAG development practices are largely ad hoc, evaluation confidence is low, and developers seek tools that support interpretability,…

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