Vellum vs Langfuse
A detailed comparison to help you choose between Vellum and Langfuse.
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Verdict: Langfuse wins
Langfuse scores 4.3/5, edging out Vellum at 3.3/5. Engineering teams running LLM apps or agents in production who want framework-agnostic tracing and evaluation with either a cheap managed cloud or a free self-hosted stack.
Vellum LLM app development platform | Langfuse Open-source LLM observability and evaluation | |
|---|---|---|
| Rating | 3.3 (1 review) | 4.3 (1 review) |
| Pricing Model | freemium | freemium |
| Starting Price | Free tier available | Free tier available |
| Best For | Founders and operators who want an always-on, memory-rich personal assistant that acts across their tools — and are comfortable paying hosting plus at-cost usage, or self-hosting on their own keys. | Engineering teams running LLM apps or agents in production who want framework-agnostic tracing and evaluation with either a cheap managed cloud or a free self-hosted stack. |
| Free Tier | ||
| API Access | ||
| Team Features | ||
| Open Source | ||
| Tags | free tierapi access | free tieropen sourceapi access |
| Visit Vellum → | Visit Langfuse → |
Vellum
Pros
- + Memory is inspectable and persistent: by day four it applied preferences I set once, and I could see and correct confidence-scored extractions
- + The permission system asked before emailing new contacts or touching protected files, then stayed out of the way on trusted work
- + Transparent billing: credits are provider cost with no markup — my two weeks of heavy use consumed about $18 in credits
- + Self-hosting the open-source build on your own keys drops the $50/month hosting layer to zero
- + Multi-channel continuity across Mac, iOS, web, Telegram, Slack and email with one identity and task list
Cons
- - The LLM development platform this listing describes is gone — no prompt management, evaluation or workflow product remains at vellum.ai
- - The $50/month Pro price is hosting only and includes zero AI usage; real cost lands near $90/month all-in for a heavy user
- - A full pivot from a small company is a real continuity risk for anyone who commits workflows to it
- - MCP server setup is CLI-level work and connector quality varies across the skills catalog
- - No enterprise SLA, SSO or team administration layer comparable to corporate-grade tooling
Langfuse
Pros
- + MIT-licensed core with free, unrestricted self-hosting — only named enterprise features like audit logs and SCIM need a licence key
- + A 5-seat team at 100k traces runs roughly $69/month versus about $420/month for the main closed alternative (Panoply's independent estimate, consistent with my bills)
- + OpenTelemetry-native tracing across OpenAI SDK, LangChain, LlamaIndex, Pydantic AI, Vercel AI SDK, CrewAI and raw OTLP
- + Graduated usage pricing is transparent and cheap: worked examples on the pricing page match my own invoices (200k units on Core = $37/month)
- + Dataset-backed evaluation with the langfuse/experiment-action GitHub step let me gate prompt changes in CI on a real test set
Cons
- - v3 self-hosting needs Postgres, ClickHouse, Redis and S3 where v2 ran on one container — a four-service system to operate
- - Heavy agent traces render slowly in the UI (issue threads #10391 and #9933 match the multi-second loads I measured)
- - Online evaluations score a sample of traffic rather than everything, so rare failure modes can go unscored
- - UI-configured evaluators cannot be triggered programmatically for scheduled pipelines in my setup
- - Owned by ClickHouse, Inc. since January 2026 — licence unchanged so far, but the vendor-independence profile shifted
Frequently Asked Questions
Which is better, Vellum or Langfuse?▼
Langfuse scores higher at 4.3/5 vs 3.3/5 for Vellum, making it the better-rated option in our comparison.
What is the difference between Vellum and Langfuse?▼
Vellum: Platform for building, testing, and deploying LLM-powered products with prompt management, evaluation, and workflow orchestration. Langfuse: Langfuse is open-source observability for LLM applications, tracing calls, running evaluations and tracking cost and latency in production.
Is Vellum or Langfuse more affordable?▼
Vellum starts at €0/mo, Langfuse starts at €0/mo. Check the comparison table above for current pricing.
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