Updated February 28, 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.
Respan provides comprehensive LLM observability with real-time monitoring, tracing, and debugging for AI applications in production. It tracks prompts, completions, latency, cost, and quality metrics across all LLM providers, with built-in evaluation tools, prompt management, and alerting. Respan gives engineering teams full visibility into their AI stack from a single dashboard.
What each tool does well, and the limitations to keep in mind.
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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.