Fiddler AI vs Helicone (2026)
Overview
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 offers both proxy and async logging modes. Popular with startups for its generous free tier and simple integration.
Key features
Core capabilities each platform advertises.
- Agentic observability across multi-step agent workflows
- Continuous evaluations from testing through production
- Inline guardrails for PII, PHI, prompt injection, and jailbreaks
- AI governance, risk, and compliance reporting
Strengths and tradeoffs
What each tool does well, and the limitations to keep in mind.
Pros
- Covers AI agents and predictive ML models in one platform
- Evaluations and guardrails run in-environment, with no external LLM API call per check
- Free tier includes real-time guardrails
- Supports SaaS, VPC, on-premises, and AWS GovCloud deployment
Cons
- The free tier covers guardrails only; observability starts on the paid Developer plan
- VPC and on-premises deployment require the Enterprise plan
- Every plan on the pricing page starts with a demo request rather than self-serve signup
- No model routing or provider failover, so a gateway is a separate tool
Pros
- Open-source with 5.2K GitHub stars and strong community support
- Minimal latency overhead (under 1ms for self-hosted)
- Flexible deployment options including cloud-hosted, self-hosted, or SDK-only
- Y Combinator-backed with SOC 2 Type II and HIPAA compliance
- No code changes required for AI Gateway features like caching and rate limiting
Cons
- Adds computational cost and one network hop for cloud deployment
- Limited pricing transparency on website
- May require infrastructure expertise for self-hosted setup
Fiddler AI or Helicone — which should you choose?
Choose Fiddler AI if you wantChoose if you want
- Governing AI agents in regulated industries
- Monitoring predictive ML models for drift and performance
- Redacting PII and PHI on agent requests and responses
Choose Helicone if you wantChoose if you want
Compare Fiddler AI and Helicone on your own traffic
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