Practical overview
When it fits
Use it during RAG development when you need structured evaluation, especially if creating a golden-answer dataset for every test query is impractical.
Who it is for
- Developers evaluating retrieval-augmented generation systems.
- Teams comparing RAG configurations or runs.
- Practitioners who want to measure RAG quality without preparing golden answers for every query.
Documented uses
- Evaluate RAG results using metrics that do not require golden answers or golden chunks.
- Run optional evaluation against reference answers when they are available.
- Review per-query scores and intermediate outputs to investigate results.
- Compare evaluation results across configurations or runs.
Requirements & limits
The project is open source under the Apache-2.0 license. The documented installation is through pip or from source; using the Vectara connector requires a Vectara account and API credentials.
- Core UMBRELA and AutoNuggetizer metrics do not require golden answers or golden chunks; reference-answer evaluation is also available.
- Some metrics use an OpenAI API key, while factual-consistency evaluation has separate HHEM and Vectara API options.
- The documented Vectara workflow needs a corpus, querying-permission API key, Customer ID and corpus key.
- The toolkit provides per-query scoring, intermediate outputs and plotting utilities for comparing runs.
Check current requirements in the official documentation. Source-based guidance does not mean OpenViST has run or independently tested this project.
Configure a Vectara RAG evaluation
Prepare a query set and configure the documented Vectara evaluation workflow.
Before you start
- Python 3.9 or later.
- A Vectara account, corpus containing indexed data, querying-permission API key, Customer ID and corpus key.
- An OpenAI API key for the default LLM judge used by some metrics.
- For factual-consistency evaluation, either a Hugging Face token and access to the Vectara HHEM model, or a Vectara API key for its Factual Consistency API.
Steps
Install the toolkit with the command below.
pip install open-rag-evalCreate a CSV of evaluation queries with a single column named
query.Edit
eval_config_vectara.yaml: set the input query file, generated-answer and result-file values, results folder, and Vectara corpus key in the connector configuration.Choose evaluator and metric settings, then use the installed command-line tool to run the evaluation.
Expected outcome
The configured workflow runs an evaluation and can produce per-query scores and result artifacts for analysis.
Guide limitations
- The guide requires credentials and configuration for the selected connector and metrics.
- The default LLM judge used in some metrics requires an OpenAI API key.
- HHEM factual-consistency evaluation requires a Hugging Face token and model access; the alternative uses Vectara's Factual Consistency API.
Compare options for Retrieval-augmented applications
These projects document a common task and share a project role. This is a source-based comparison, not an execution benchmark or a guarantee of interchangeability.
| Project | Documented purpose | Platform | Access and requirements |
|---|---|---|---|
| Open Rag Eval | Evaluate RAG results using metrics that do not require golden answers or golden chunks. | Server | The project is open source under the Apache-2.0 license. The documented installation is through pip or from source; using the Vectara connector requires a Vectara account and API credentials. |
| Sentrev | Compare retrieval performance across embedding models on a document collection. | CLI | The project is an open-source Python package under the MIT license. Its README documents installation with pip or from source. |
| Diragnosis | Generate synthetic evaluation questions from supplied documents. | Docker, Linux, macOS, Self-hosted | The repository identifies the software as open source under the MIT license. The README documents a local Docker application and a pip-installable Python package. |
Sources & review
Source record details
- Source availability
- Active
- Sources checked
- 13 October 2026
- Original website title
- vectara/open-rag-eval · Official homepage title · retained in its source language

