Promptfoo vs 
Phoenix
Promptfoo vs Phoenix compared for 2026 — features, license, ease of use, performance and which one to choose. Unit tests for your prompts vs Trace, evaluate and debug LLM apps.
Updated regularly · curated by OpenSourceAI.tech
Promptfoo vs Phoenix at a glance
| Spec | Promptfoo | Phoenix |
|---|---|---|
| Category | LLM / RAG framework | LLM / RAG framework |
| Type | Prompt testing | LLM observability |
| License | MIT | Elastic-2.0 |
| Runs locally | Yes | Yes |
| Primary language | TypeScript | Python |
| Ease of use | Beginner | Intermediate |
| Best for | teams shipping prompts to production | finding why a RAG pipeline fails |
| GitHub stars | 23.3k | 10.6k |
How Promptfoo and Phoenix score
| Criterion | Promptfoo | Phoenix |
|---|---|---|
| Popularity | 3.5 | 3.0 |
| Maintenance | 5.0 | 5.0 |
| Ease of use | 5.0 | 3.5 |
| Privacy | 5.0 | 5.0 |
| License freedom | 5.0 | 3.5 |
Scores are computed automatically from public signals — GitHub stars (popularity), recent commit activity (maintenance), license type (freedom), local-first design (privacy) and onboarding complexity (ease of use). Indicative, not a verdict.
What each one is
Promptfoo
Promptfoo runs your prompts against test cases across models, catching regressions before they reach production, and includes red-teaming checks.
- Regression tests for prompts
- Compares models side by side
- Built-in security red-teaming
Phoenix
Phoenix from Arize traces LLM applications, surfaces failure clusters and runs evaluations, all runnable locally in a notebook or as a server.
- Runs locally, even in a notebook
- Clusters failures to find patterns
- Built-in LLM evaluators
Key differences
Promptfoo is prompt testing, while Phoenix is lLM observability. Their licenses differ (MIT vs Elastic-2.0), which matters if you ship a commercial product. Promptfoo leans more beginner-friendly, whereas Phoenix is more suited to intermediate users. In short, Promptfoo fits teams shipping prompts to production, and Phoenix fits finding why a RAG pipeline fails.
Which should you choose?
Choose Promptfoo for teams shipping prompts to production. Choose Phoenix for finding why a RAG pipeline fails.
There is rarely one winner — many setups use both. The right pick depends on your hardware, your team's skills, and whether you value simplicity or control.
Frequently asked questions
Is Promptfoo or Phoenix easier to use?
Promptfoo is generally the easier of the two to get started with, while Phoenix rewards more setup with more control.
Are Promptfoo and Phoenix free?
Promptfoo is free and open source (MIT), and Phoenix is free and open source (Elastic-2.0). Neither charges for the core software.
Can I run Promptfoo and Phoenix locally?
Promptfoo: yes · Phoenix: yes. Both can be used without sending your data to a third-party cloud where their setup allows.
Promptfoo vs Phoenix — which should I pick in 2026?
Choose Promptfoo for teams shipping prompts to production. Choose Phoenix for finding why a RAG pipeline fails.
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