Suggestions appear as you type. Use the up and down arrows to choose one and Enter to open it.

This page's audience our own tag's counts — open to see them
–Visits
–Page views
–Clicks to vendors
–Time on page
–Reading now
Clicks to vendors, by tool
  • –
Top countries
  • –
Devices
  • –

– · visits, page views and clicks counted by our own tag, which counts more than our checked analytics; every figure rounded down · how we count

Fiddler Guardrails review

Freemium#9 of 23 in AI Guardrail Software

Affordable runtime evaluation with policy enforcement, detection, and gateway integrations.

8.2/10Editor score
Visit Fiddler
Fiddler Guardrails8.2 Visit Fiddler

Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026

Fiddler Guardrails is a runtime policy enforcement layer for AI agents and LLM applications. It evaluates prompts and responses for prompt injection, jailbreaks, unsafe content, hallucinations, PII, and PHI, then applies configured allow, block, or redact actions. Teams can define safety, security, privacy, and accuracy policies, set custom thresholds, and evaluate faithfulness and groundedness. The product is aimed at enterprises and regulated organizations deploying AI systems in production through web and API access.

Pricing is accessible for teams starting with runtime evaluation. The Free plan includes real-time guardrails, protection against several common AI risks, and latency under 80ms. The Developer plan costs $0.002 per trace and adds unified AI observability, custom evaluators, bring-your-own-judge support, visualization-driven insights, role-based access control, SSO, and SaaS deployment. Enterprise adds enterprise-grade guardrails and infrastructure scalability, plus SaaS, VPC, or on-premises deployment, dedicated communication channels, a named Customer Success Manager, and customized onboarding.

Fiddler Guardrails fits teams that want policy checks inline with LLM traffic rather than a separate review workflow. Its gateway approach supports NVIDIA NeMo Guardrails, LiteLLM, Kong, and AgentGateway, while API access is available through Node.js, Python, cURL, or other HTTP clients. The main trade-off is scope: teams needing a broad set of gateway integrations or straightforward published Enterprise pricing may prefer a different option. Choose Fiddler Guardrails when runtime detection, configurable enforcement, and low-cost evaluation are priorities; look elsewhere if your deployment depends on integrations beyond its listed gateway ecosystem.

Fiddler Guardrails pros and cons

  • Where it wins
    • Free real-time guardrails cover hallucinations, toxicity, PII/PHI, and jailbreaks
    • $0.002-per-trace Developer pricing adds observability and custom evaluators
    • Supports allow, block, or redact actions with configurable policy thresholds
  • Where it doesn't
    • Enterprise pricing requires contacting the vendor
    • Gateway integrations center on four listed frameworks
    • Advanced deployment options are concentrated in the Enterprise plan

Fiddler Guardrails fact sheet, pricing and score →

Advertiser disclosure: iTechGuides is reader-supported. Vendors can pay for top positions in our rankings and for a place on other products' pages, and we may earn a commission when you click some links. Bought places stand at the number bought; this page and our disclosure say so. Paying vendors may get a fuller, more detailed review from our editors, and that review can change their score. How we rank.

Last updated · How we research and update