Key features
Core capabilities each platform advertises.
Data not available
- Multi-turn agent simulation testing
- LLM evaluation with custom evaluators
- OpenTelemetry-native tracing
- Prompt & model management
- Dataset management from production traces
Updated March 27, 2026
Helicone is an open-source LLM observability and proxy platform. By adding a single line of code, developers get request logging, cost tracking, caching, rate limiting, and analytics for their LLM applications. Helicone supports all major LLM providers and offers both proxy and async logging modes. Popular with startups for its generous free tier and simple integration.
Open-source LLMOps platform for testing, evaluating, and monitoring AI agents. Differentiated by multi-turn agent simulation testing.
Core capabilities each platform advertises.
What each tool does well, and the limitations to keep in mind.
Pros
Cons
Pros
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Respan lets you trace LLM and agent calls across any model or framework, A/B test prompts on production traffic, and route requests across 500+ models through one gateway.
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