Promptfoo vs 
Langfuse
Promptfoo vs Langfuse compared for 2026 — features, license, ease of use, performance and which one to choose. Unit tests for your prompts vs See what your LLM app actually did.
Updated regularly · curated by OpenSourceAI.tech
Promptfoo vs Langfuse at a glance
| Spec | Promptfoo | Langfuse |
|---|---|---|
| Category | LLM / RAG framework | LLM / RAG framework |
| Type | Prompt testing | LLM observability |
| License | MIT | MIT |
| Runs locally | Yes | Yes |
| Primary language | TypeScript | TypeScript |
| Ease of use | Beginner | Intermediate |
| Best for | teams shipping prompts to production | debugging and monitoring LLM apps in production |
| GitHub stars | 23.3k | 31.3k |
How Promptfoo and Langfuse score
| Criterion | Promptfoo | Langfuse |
|---|---|---|
| Popularity | 3.5 | 4.0 |
| Maintenance | 5.0 | 5.0 |
| Ease of use | 5.0 | 3.5 |
| Privacy | 5.0 | 5.0 |
| License freedom | 5.0 | 5.0 |
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
Langfuse
Langfuse traces every LLM call, tool use and cost in your application, with prompt management and evaluation built in — self-hostable.
- Full tracing of chains and agents
- Cost and latency tracking
- Self-hosted, MIT licensed
Key differences
Promptfoo is prompt testing, while Langfuse is lLM observability. Promptfoo leans more beginner-friendly, whereas Langfuse is more suited to intermediate users. In short, Promptfoo fits teams shipping prompts to production, and Langfuse fits debugging and monitoring LLM apps in production.
Which should you choose?
Choose Promptfoo for teams shipping prompts to production. Choose Langfuse for debugging and monitoring LLM apps in production.
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 Langfuse easier to use?
Promptfoo is generally the easier of the two to get started with, while Langfuse rewards more setup with more control.
Are Promptfoo and Langfuse free?
Promptfoo is free and open source (MIT), and Langfuse is free and open source (MIT). Neither charges for the core software.
Can I run Promptfoo and Langfuse locally?
Promptfoo: yes · Langfuse: yes. Both can be used without sending your data to a third-party cloud where their setup allows.
Promptfoo vs Langfuse — which should I pick in 2026?
Choose Promptfoo for teams shipping prompts to production. Choose Langfuse for debugging and monitoring LLM apps in production.
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