The rows worth reading.
Langfuse is well-regarded open-source observability that fully open-sourced in June 2025 and was acquired by ClickHouse in January 2026. It covers the basics — traces, evals, datasets — but lacks agent-first features like health scoring, AI cost optimization, guardrails, and a conversational copilot. Self-hosting is 'free' but requires a ClickHouse cluster ($200–800/month infra cost). Zespan is cloud-native, agent-first, and fully managed.
| Zespan | Langfuse | |
|---|---|---|
| Free tier | 10K traces/month | 100K units/month (with limits) |
| Starting price | $39/month | $29/month (Core) |
| Managed cloud | Fully managed | Cloud or self-host |
| Self-host infra cost | Not available | ClickHouse: $200–800/month |
| Agent auto-discovery | Zero config | Not available |
| Agent health scoring | A–F composite score | Not available |
| Multi-agent delegation graph | Agent Graphs (Nov 2025) | |
| AI cost optimizer | Forecast + recs | Not available |
| Guardrails | 7 types, pre/post | Not available |
| LLM-as-judge auto-evals | 12 templates, automatic | Custom only, manual |
| Natural language query | ZespanPilot NLQ | Not available |
| Incident management | Full state machine | Not available |
| OpenTelemetry native |
Which one fits
Pick Zespan when
You want fully managed — no ClickHouse cluster to operate.
You need guardrails, runtime safety, or PII redaction in production.
You want agent health scoring, cost forecasting, and anomaly detection.
Your team builds on multiple frameworks, not just LangChain.
You want an AI copilot for querying observability data.
Pick Langfuse when
Open-source license is a hard requirement for compliance or vendor policy reasons.
You want full data sovereignty and are willing to operate ClickHouse yourself.
You're already in the ClickHouse ecosystem and the ClickHouse acquisition is a feature, not a risk.
Common questions
Is Langfuse's self-hosted option actually free?
The software license is free (MIT), but you still need to operate a ClickHouse cluster, which runs $200–800/month on most cloud providers. For small teams, Zespan's $39/month managed plan is often cheaper total.
How does Zespan compare on evaluations?
Both platforms support evaluations and datasets. Zespan's auto-evaluators run automatically on every new trace using 12 built-in LLM-as-judge templates — no manual setup. Langfuse's evaluations require manual configuration and trigger.
Does Zespan support agent graphs like Langfuse does?
Yes. Zespan has had first-class multi-agent delegation graphs since launch. The delegation graph shows which agents hand off to which, with cost and latency per hop. Langfuse added Agent Graphs in November 2025.
What happened to Langfuse after the ClickHouse acquisition?
Langfuse was acquired by ClickHouse in January 2026. The long-term product roadmap and pricing independence are now tied to ClickHouse's plans. Zespan is independent.