Fiddler Guardrails
Fiddler Guardrails: Affordable runtime evaluation with policy enforcement, detection, and gateway integrations. Ranked #9 of 23 in AI Guardrail Software by our editors (8.2/10); pricing: Free plan; best for teams needing affordable runtime evaluation.
At a glance
- Editor score8.2 / 10
- PricingFree plan
- Best forTeams needing affordable runtime evaluation
- Free planYes
- Paid from$0.002/unit usage-based
- Prompt injection defenseYes
- Founded2018 · Palo Alto, California, United States
- Facts checked21 Sep 2026
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
Our verdict on Fiddler Guardrails
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.
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Fiddler Guardrails pricing
All 3 Fiddler Guardrails plans and prices →
Fiddler Guardrails fact sheet
| Free plan | Yes |
|---|---|
| Paid from | $0.002/unit usage-based |
| Deployment | Hybrid |
| Prompt injection defense | Yes |
| PII detection | Yes |
| Jailbreak detection | Yes |
| Custom policies | Yes |
| SDK languages | Python, Node.js |
| Deployment | Cloud, Self-hosted |
| Platforms | Web |
| Compliance & security | SOC 2, HIPAA, SSO/SAML |
| Support | Docs |
| Built for | Enterprise (editorial estimate) |
| Integrations | 4 integrations: NVIDIA NeMo Guardrails, LiteLLM, Kong, AgentGateway |
| Pricing | Free plan (source) |
| Website | fiddler.ai |
| Facts checked | 21 Sep 2026 |
Fiddler Guardrails integrations
Fiddler Guardrails lists 4 integrations on its own site.
- NVIDIA NeMo Guardrails
- LiteLLM
- Kong
- AgentGateway
Alternatives to Fiddler Guardrails
- Enkrypt AI GuardrailsBroad runtime controls for teams securing production AI systems.9.4
- VotalAIBroad hybrid guardrails for prompts, agents, data, tools, and audit workflows.9.2
- OpenAI GuardrailsA flexible, OpenAI-focused guardrail framework for validating LLM workflows.9.0
See all Fiddler Guardrails alternatives →
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Reviewed by iTechGuides Editors · Editorial team · Updated Oct 2026
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