Promptfoo vs Ragas
Both are eval frameworks tools. Here is how they actually differ on price, billing model and deployment.
Promptfoo
The de-facto open-source CLI for LLM eval and red-teaming, driven by declarative YAML. MIT-licensed, ~23.5k stars, and acquired by OpenAI in March 2026 - still open source, now part of OpenAI Frontier.
Ragas
The most-used open-source RAG evaluation library, and deliberately just a library - metrics with no orchestration, no dashboard and no platform. Its ground-truth-free metrics are the reason it wins on speed of adoption.
| Promptfoo | Ragas | |
|---|---|---|
| Category | Eval Frameworks | Eval Frameworks |
| Our rating | 4/5 | 4/5 |
| Starting price | $0 | $0 (open source) |
| Billing meter | No usage metering | No usage metering |
| Free plan | Yes | Yes |
| Free self-hosting | Yes, free | Yes, free |
| Best for | Security and CI teams who want config-driven LLM eval plus serious red-teaming, from an OSS tool with no seat cost | Teams building RAG pipelines who want fast, meaningful retrieval and generation metrics during development, and who already have or want a separate tracing platform. |
Our verdict on Promptfoo
The clearest pick if red-teaming and security testing are part of your eval story, and its YAML-in-git approach fits CI cleanly. The OpenAI acquisition in March 2026 is the thing to weigh - the commitment to stay MIT is on the record, but you are now betting on OpenAI's stewardship of the project. For the free tier alone it is still an easy yes.
Full Promptfoo review →Our verdict on Ragas
Ragas is the best answer to a narrow question, and its narrowness is the point. It is the most-used open-source RAG evaluation library in 2026 and it is purely a metrics library - no orchestration, no dashboard, no platform ambitions. That makes it the fastest thing here to get useful numbers out of, and it composes with whatever tracing tool you already run instead of competing with it. The standout capability is ground-truth-free metrics, which matter enormously in practice because the honest state of most teams is that they have no labelled dataset and are not going to build one soon. Two real caveats. Scoring is LLM-judge-based, so every evaluation run costs model calls and inherits judge bias - a known methodological weakness where a judge tends to be generous toward output from its own model family. And it is RAG-specific. For agents or tool-calling workflows you want DeepEval or a platform built for that shape.
Full Ragas review →Frequently Asked Questions
What is the main difference between Promptfoo and Ragas?
Promptfoo: Security and CI teams who want config-driven LLM eval plus serious red-teaming, from an OSS tool with no seat cost Ragas: Teams building RAG pipelines who want fast, meaningful retrieval and generation metrics during development, and who already have or want a separate tracing platform. Both sit in Eval Frameworks, so the decision usually comes down to billing model and deployment rather than raw capability.
Which is cheaper, Promptfoo or Ragas?
It depends entirely on your workload shape, because they meter differently - Promptfoo bills on no usage metering and Ragas bills on no usage metering. Published starting prices are $0 and $0 (open source) respectively, but those numbers are not comparable until you apply them to the same traffic. Use our cost calculator to model both against your own request volume and span count.
Can I self-host Promptfoo or Ragas?
Promptfoo: Yes, free. Ragas: Yes, free. Free self-hosting means no licence fee, not no cost - you still own the infrastructure, upgrades and on-call.