Updated March 10, 2026
Fiddler AI is an enterprise platform for observing, evaluating, and governing AI agents and ML models, with guardrails that run in your own environment.
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 can function as both a gateway proxy and a logging-only integration.
Core capabilities each platform advertises.
What each tool does well, and the limitations to keep in mind.
Pros
Cons
Pros
Cons
Choose Fiddler AI if you wantChoose if you want
Choose Helicone if you wantChoose if you want
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.
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