Comparison
Nexus vs Opik for AI Agent Observability
Opik is the open-source LLM evaluation and observability platform by Comet. It's self-hostable, evaluation-first, and free. Nexus is a managed, agent-first observability platform. Here's when each tool is the right fit.
TL;DR
Choose Nexus if you…
- ✓ Running AI agents in production — not in evaluation
- ✓ Need per-agent health cards, error rates, and alerting
- ✓ Want a managed platform with no DevOps overhead
- ✓ Need a simple $9/mo flat price, no infrastructure costs
Choose Opik if you…
- ✓ Need LLM evaluation datasets and scoring workflows
- ✓ Want full data control — self-hostable on your infra
- ✓ Need prompt versioning and A/B comparison
- ✓ Your budget is $0 and you can run your own server
Feature Comparison
| Feature | Nexus | Opik |
|---|---|---|
| Primary focus | Agent runtime observability | LLM evaluation and annotation |
| Deployment model | ✓ Fully managed — sign up and start | Self-hosted (Docker/K8s) or Comet cloud |
| Per-agent health dashboard | ✓ Error rates, 7d trends, alerting | Project-level view, not agent-level |
| LLM evaluation datasets | ✗ Not supported | ✓ Core feature — eval suites and scoring |
| Human annotation / feedback | ✗ Not supported | ✓ Built-in annotation UI |
| Prompt versioning | Not built-in | ✓ Prompt library with version history |
| Webhook / email alerts | ✓ Included on Pro plan | Not available |
| Multi-framework support | ✓ LangChain, CrewAI, AG2, DSPy, more | ✓ OpenAI, LangChain, LiteLLM, more |
| Data sovereignty | Managed (Cloudflare edge) | ✓ Full data control on self-hosted |
| Pricing | Free tier + $9/mo flat (Pro) | Free open-source + Comet cloud paid plans |
The honest take
Opik is the open-source evaluation-first platform by Comet — genuinely excellent if you need a self-hosted LLM tracing and evaluation solution. You get prompt versioning, evaluation datasets, human annotation, and automatic LLM-as-judge scoring. If your primary goal is building a systematic evaluation pipeline for LLM quality, Opik is hard to beat at zero license cost.
The tradeoff is operational: self-hosting requires Docker or Kubernetes, and you own the maintenance burden. If your team doesn't have a DevOps culture, this adds up fast. Comet's managed cloud reduces this but comes with its own pricing.
Nexus is purpose-built for production agent monitoring — not evaluation. You get per-agent health cards, error rate trends, webhook alerts when things go wrong, and a managed backend with zero infrastructure overhead. The $9/mo flat price is predictable for teams with high-volume agent pipelines, and setup takes 5 minutes without touching Docker.
Many teams use both: Opik for pre-production evaluation and prompt optimization, Nexus for post-deployment runtime health. If you're only choosing one and your question is “are my production agents healthy?” rather than “are my LLM outputs high quality?” — Nexus is the right answer.
Try Nexus free
Managed agent observability. Free tier, no credit card required. Works with LangChain, CrewAI, AG2, DSPy, and more.