LangChain vs Langfuse

LangChain

Langfuse

LangChain · 18 features

• Agents — Tool-using agents with reasoning loops.
• Chains (LCEL) — LangChain Expression Language — pipe primitives into chains.
• Checkpointers (LangGraph) — Persist agent state to SQL, Mongo, Redis, Postgres.
• Document Loaders — 150+ loaders for PDF, HTML, Notion, Google Drive, S3, GitHub, etc.
• Human-in-the-loop — Pause agent for approval, then resume.
• LangGraph — Stateful graph-based agent runtime. Durable, replayable, human-in-the-loop.
• LangGraph Platform — Managed hosting for LangGraph agents with state persistence.
• LangGraph Studio — Desktop IDE for debugging agent graphs.
• LangServe — Deploy chains as FastAPI endpoints.
• Memory — Buffer, summary, entity, vector memory stores.
• Output Parsers — Structured JSON, Pydantic schemas, function calling.
• Prompt Templates — Templating + partial filling + output parsers.
• RAG (Retrieval-Augmented Generation) — Standard patterns + 50+ retrievers.
• Streaming — First-class streaming at every layer.
• Subgraphs — Compose agent graphs hierarchically.
• Text Splitters — Recursive, token, semantic splitters for chunking.
• Tools — 400+ pre-built tools (web search, code, databases, APIs).
• Vector Store Integrations — 60+ vector DBs (Pinecone, Chroma, Weaviate, PGVector, Qdrant, Milvus).

Langfuse · 16 features

• Annotation Queues — Human reviewers rate traces. Unlimited on Pro+.
• Dashboards — Aggregate metrics, cost, quality across projects.
• Datasets — Curate test sets from production traces. Run experiments.
• EU Cloud Region — GDPR-compliant hosting in EU.
• Evaluations — LLM-as-judge, manual scores, custom model-graded evaluators.
• LLM Cost Tracking — Automatic cost calculation per provider/model.
• OpenTelemetry Native — OTel SDK → Langfuse endpoint works out of box.
• Playground — Test prompts + models + variables live.
• Prompt Management — Version, tag, label prompts. Reference from code by label.
• Public API — Full REST API for ingest, query, prompt management.
• Python @observe decorator — One-line decorator to trace any function.
• Self-Hosting — Docker Compose + k8s Helm chart.
• Sessions — Group related traces (conversations, agent runs).
• Tracing — Capture every LLM call, tool call, nested span with inputs/outputs/cost.
• Users Tracking — Segment traces by user ID, track per-user cost.
• Webhooks — Subscribe to trace completion events.