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AI · November 6, 2023

Open-source model and scorecard for measuring hallucinations in LLMs

Hi all! This morning, we released a new Apache 2.0 licensed model on HuggingFace for detecting hallucinations in retrieval augmented generation (RAG) systems. What we've found is that even when given a "simple" instruction like "summarize the following news article," every LLM that's available hallucinates to some extent, making up details that never existed in the source article -- and some of them quite a bit. As a RAG provider and proponents of ethical AI, we want to see LLMs get better at this. We've published an open source model, a blog more thoroughly describing our methodology (and…

Open-source model and scorecard for measuring hallucinations in LLMs launched on November 6, 2023 with 65 votes, #1,135 of 4,333 launches that month and more than 90% of that year's launches. The site was still online in September 2026, 2 years on.

In plain words

An open-source model and evaluation tool for detecting hallucinations in large language models, particularly in retrieval augmented generation systems. It identifies instances where LLMs fabricate details not present in source material during tasks like summarization. The tool includes an Apache 2.0 licensed model on HuggingFace, evaluation results comparing popular LLMs, and methodology documentation. Designed for developers and organizations building RAG systems who want to measure and improve hallucination rates in their models.

written from the facts on this page · September 2026

From the sources

Vectara launches open-source Hallucination Evaluation Model (HEM) that provides a FICO-like score for grading how often a generative LLM hallucinates in Retrieval Augmented Generation (RAG) systems. Today, we’re happy to announce the release of our open-source Hallucination Evaluation Model! One of the top concerns of enterprises considering adopting generative AI has been the possibility of LLMs generating hallucinations . Hallucinations come in many forms that could negatively affect a business: While many businesses acknowledge the benefits of generative AI, the risks of these hallucinations have held many back. Some attempts have been made in the past to quantify or at least qualify…from vectara.com

In the maker’s words, at launch

Hi all! This morning, we released a new Apache 2.0 licensed model on HuggingFace for detecting hallucinations in retrieval augmented generation (RAG) systems. What we've found is that even when given a "simple" instruction like "summarize the following news article," every LLM that's available hallucinates to some…

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