Langfuse
Open source LLM engineering platform for observability, metrics, evaluations, prompt management, and datasets
10K+
GitHub Stars
3B+
Traces/Month
4K+
Companies
Overview
Langfuse is an open source LLM engineering platform that provides comprehensive observability, tracing, and evaluation capabilities for AI applications. Built with a modular architecture, it offers production-grade tracing for complex LLM chains and agents, automated evaluations, prompt management with versioning, and cost tracking across providers. Langfuse was acquired by ClickHouse in 2025, bringing enterprise-scale data infrastructure to LLM observability. It integrates with all major frameworks including LangChain, LlamaIndex, OpenAI SDK, and supports self-hosting for data sovereignty requirements.
The Verdict
Who Should Use Langfuse?
Best For
- Teams needing full data control (self-hosted)
- Multi-model, multi-framework architectures
- Production LLM debugging and optimization
- Cost tracking across multiple providers
- Companies with compliance requirements
Not Ideal For
- Pure LangChain shops (LangSmith more native)
- Teams wanting zero setup (use Helicone gateway)
- Simple single-model apps (overkill)
- Non-technical teams needing hand-holding
What's Great
- Fully open source with self-hosting option
- Framework-agnostic - works with any LLM stack
- Production-grade tracing with nested spans
- Built-in prompt management and versioning
- LLM-as-judge automated evaluations
- Real-time cost tracking per trace
- ClickHouse backing for massive scale
Watch Out For
- Self-hosted requires DevOps expertise
- UI less polished than commercial alternatives
- Learning curve for full feature utilization
- Some advanced features require Pro tier
- Limited native integrations vs LangSmith
Pricing
Hobby
$0
50K observations/mo, unlimited users
Pro
$59/mo
Unlimited observations, advanced features
Team
$499/mo
SSO, RBAC, priority support
Self-Hosted
Free / Enterprise
Full control, your infrastructure
View all features & details
Core Features
- LLM tracing with nested spans
- Prompt management & versioning
- LLM-as-judge evaluations
- Human annotation workflows
- Dataset management
- Cost & latency analytics
- Session replay & debugging
- A/B testing support
Integrations
- LangChain / LangGraph
- LlamaIndex
- OpenAI SDK
- Anthropic SDK
- Vercel AI SDK
- Haystack
- Instructor
- Flowise / Langflow
Deployment
- Managed cloud (EU/US)
- Self-hosted (Docker/K8s)
- ClickHouse data backend
- PostgreSQL metadata store
- S3-compatible blob storage
Security & Compliance
- SOC 2 Type II
- GDPR compliant
- SSO (Enterprise)
- RBAC permissions
- Data residency options
How It Compares
| Feature | Langfuse | LangSmith | Helicone | W&B Weave |
|---|---|---|---|---|
| Open Source | Yes (MIT) | No | Yes | No |
| Self-Hosted | Yes | No | Yes | No |
| Free Tier | 50K obs/mo | 5K traces/mo | 100K req/mo | Limited |
| LangChain Native | Via SDK | Native | Via proxy | Via SDK |
| Multi-Provider | All providers | All providers | Gateway proxy | All providers |
| Prompt Mgmt | Built-in | Built-in | No | No |
| Evaluations | LLM-as-judge | Online evals | Basic | Advanced |
| Starting Price | $0 (self-host) | $39/mo | $0 | $0 |
| Best For | Full control | LangChain users | Simple proxy | ML teams |
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