Langfuse vs Respan (2026)
Updated February 28, 2026
vs
Overview
Rating
10.0 / 10
Rating
10.0 / 10
Best For
Teams who want open-source LLM observability they can self-host and customize
Best For
Engineering and product teams running AI agents and LLM apps in production
Product Summary
Langfuse is an open-source LLM engineering platform for tracing, evals, and prompt management, self-hosted or on Langfuse Cloud with a free plan.
Product Summary
Respan is LLM observability built into an AI router: nested traces for every agent run, evals on live production traffic, and a click from any score to its trace.
Starting Price
Free
Starting Price
$0
Free Trial
No
Free Trial
Yes
Free Version
Yes
Free Version
Yes
Website
Website
Key features
Core capabilities each platform advertises.
- Tracing for LLM calls, tool runs, and agent steps
- Python and TypeScript SDKs plus OpenTelemetry
- LLM-as-a-judge and custom evaluations
- Datasets and experiments
- Prompt management and playground
- Nested traces for every LLM call, tool run, and agent turn
- Threads for multi-turn sessions
- Online evals on live production traffic
- LLM-judge, code, and human evaluators
- Datasets from production logs and experiments at scale
- Monitors with Slack, email, and webhook alerts
- Prompt versioning and deployment without code changes
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- MIT-licensed core, self-hostable with Docker Compose or Kubernetes
- Tracing, evals, and prompt management in one tool
- Unlimited users on paid cloud plans
- Free Hobby plan with 50k units a month
- Native SDKs plus OpenTelemetry for other languages
Cons
- No LLM gateway, so routing, failover, and spend limits need a separate tool
- Hobby plan keeps 30 days of data and caps at 2 users
- Enterprise SSO and RBAC need the $300/month Teams add-on on Pro
- Self-hosting means running and scaling Langfuse's services yourself
Pros
- Every score links to the trace that produced it
- Evals run on live production traffic, not only on test sets
- Built into the router, so there's no separate gateway to integrate
- Monitors alert the moment a metric breaches
- Unlimited seats on the free plan
Cons
- The free plan retains data for 7 days
- The free plan includes 1k scores and 2 evaluators
- Ingestion throughput is metered per tier, starting at 412 logs per minute on Free
Langfuse or Respan — which should you choose?
Choose Langfuse if you wantChoose if you want
- Tracing and debugging LLM apps and agents
- Self-hosting LLM observability
- Versioning prompts across environments
- Scoring outputs with LLM judges and human review
Choose Respan if you wantChoose if you want
- Debugging agent failures down to the step that broke
- Catching quality regressions before users report them
- Turning production failures into test datasets
- Testing a prompt or model change against real cases before shipping
- Attributing LLM cost to each end customer
Compare Langfuse and Respan on your own traffic
10KFree traces/mo
1,000+Models
5 minSetup
Respan lets you trace LLM and agent calls across any model or framework, A/B test prompts on production traffic, and route requests across 1,000+ models through one gateway.
Try Respan free