Helicone

Open-source observability layer for LLM API calls.

Best use cases
LLM request monitoring
Cost tracking
Latency analysis
Prompt logging
Production debugging
Pros
Open source
Provider-agnostic
Easy API-level integration
Cost and usage tracking
Works well in production
Cons
Less opinionated guidance than LangSmith
UI is more utilitarian
Advanced features require hosted plan
Pricing
freemium
Free open-source version + paid hosted plans
Alternatives