Langfuse vs Promptfoo: Observability, Prompts & Evals Comparison
Compare Langfuse and Promptfoo side by side. Both are tools in the Observability, Prompts & Evals category.
Updated March 10, 2026
The short answer
Choose Langfuse if fully open-source with MIT license and free for commercial use with no usage limits.
Choose Promptfoo if completely free and open source (MIT license).
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Quick Comparison
| Category | Observability, Prompts & Evals | Observability, Prompts & Evals |
| Pricing | Open Source | — |
| Best For | Teams who want open-source LLM observability they can self-host and customize | — |
| Website | langfuse.com | promptfoo.dev |
| Key Features |
| — |
| Use Cases |
| — |
Pros & Cons: Langfuse vs Promptfoo
- +Fully open-source with MIT license and free for commercial use with no usage limits
- +Acquired by ClickHouse in January 2026, providing strong backing and future investment
- +Active development with strong community support and comprehensive documentation
- +Transparent pricing model based on units rather than complex metric calculations
- +Deep integrations with major frameworks like LangChain, OpenAI, and LlamaIndex
- −Recent acquisition by ClickHouse may lead to platform changes and strategic shifts
- −Smaller team of 7 employees may impact support capacity
- −Enterprise pricing at $3,450-$5,700/month can be expensive for mid-sized teams
- +Completely free and open source (MIT license)
- +Fast with quality features like live reloads and caching
- +Built-in red teaming and security vulnerability scanning
- +Trusted by large companies with strong community
- −CLI-focused creates friction for non-technical users
- −Limited observability for complex production agents
- −No version control for prompts, data, or metrics
- −Offline nature hits ceiling for production scale
Pricing: Langfuse vs Promptfoo
- · MIT license
- · Up to 10k probes/month
- · All core features
- · CLI and browser UI
- · Hosting costs
- · Database expenses
- · LLM API calls
- · Variable by usage
- · Advanced features
- · Higher probe limits
- · Priority support
- · Custom security
When to Choose Langfuse vs Promptfoo
- Self-hosted LLM monitoring
- Open-source tracing for AI applications
- Prompt versioning and management
About Langfuse
Langfuse is an open-source LLM engineering platform that provides comprehensive tools for traces, evaluations, prompt management, and metrics to debug and improve LLM applications. Founded in Berlin, Germany in 2022, Langfuse quickly became a leading platform in the LLM observability space. The platform features MIT-licensed open-source core with no usage limits for commercial use, making it highly accessible to teams of all sizes. Langfuse offers deep integration with popular frameworks including LangChain, OpenAI, LlamaIndex, and LiteLLM. The platform provides detailed tracing capabilities, evaluation tools, comprehensive prompt management, and rich metrics tracking. In January 2026, Langfuse was acquired by ClickHouse, Inc., marking a significant transatlantic venture exit and validating the platform's technology and market position. The acquisition demonstrates the value of Langfuse's approach to LLM observability, evaluations, and prompt management.
About Promptfoo
Promptfoo is an open-source tool for testing prompts, agents, and RAGs, with AI red teaming, pentesting, and vulnerability scanning for LLMs. Built under MIT license, Promptfoo was originally developed for LLM apps serving over 10 million users in production. The platform compares performance across GPT, Claude, Gemini, Llama, and more with simple declarative configs supporting command line and CI/CD integration. The Community version includes up to 10,000 probes monthly at no charge, with infrastructure costs typically USD 50-500 monthly for hosting and LLM API calls. Developers praise Promptfoo for its speed, quality-of-life features like live reloads and caching, security features including red teaming, and budget-friendly open-source model. However, the CLI-focused approach creates friction for non-technical team members, and the platform lacks end-to-end observability, version control for prompts, and test management features needed for complex production agents.
What is Observability, Prompts & Evals?
Tools for monitoring LLM applications in production, managing and versioning prompts, and evaluating model outputs. Includes tracing, logging, cost tracking, prompt engineering platforms, automated evaluation frameworks, and human annotation workflows.
Browse all Observability, Prompts & Evalstools →Other Observability, Prompts & Evals Tools
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