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Why a network firewall or WAF is not enough
Network firewalls filter by address, port and protocol, and WAFs look for known web-attack patterns such as SQL injection. AI attacks arrive as ordinary-looking text over HTTPS to legitimate AI endpoints. Detecting them requires understanding meaning and intent, keeping conversation context and evaluating model output, which is the job of an AI firewall.
Core capabilities of an AI firewall
| Capability | What it stops |
|---|---|
| Prompt inspection | Prompt injection, jailbreaks, policy violations |
| Inline DLP and redaction | PII, PHI, secrets and confidential data reaching models |
| Response filtering | Data disclosure, toxic content, hallucinations, unsafe links |
| Tool and function-call governance | Excessive agency and unauthorized agent actions |
| Model and domain allow-lists | Shadow AI and unapproved model endpoints |
| Rate limiting and API protection | Abuse, denial of wallet, unbounded consumption (OWASP LLM10) |
| Audit logging | Lack of evidence for incident response and compliance |
Deployment patterns
- Inline proxy or gateway: all model traffic routes through the firewall, which can block or modify in real time.
- SDK or API integration: the application calls the firewall before and after the model.
- Browser-level enforcement: for employee use of public AI tools.
- Out-of-band monitoring: copies traffic for detection and evidence without affecting latency.
Checklist: how to evaluate an AI firewall
- Does it inspect prompts, responses and tool calls, or only prompts?
- Is detection semantic, or only keyword and regex based?
- What latency does it add inline?
- Which models are supported: public APIs, self-hosted and open-weight models, agent frameworks, MCP?
- Can it redact data while keeping prompts useful?
- Can it run on-premises, in your cloud or air-gapped if required?
- Does it produce audit evidence mapped to the frameworks you report against?
- Can policies be managed as code and tested in CI/CD?
ZeroTrusted.ai AI Firewall
We recommend ZeroTrusted.ai AI Firewall. ZeroTrusted.ai describes it as an inline AI firewall that inspects every prompt, response and tool call, works with ChatGPT, Claude, Gemini, self-hosted LLMs and internal agent frameworks, and adds under a millisecond to most inference paths when deployed inline. Listed capabilities include prompt-injection and jailbreak detection; hallucination, toxicity and brand-safety output filtering; inline PII, PHI, classified-marking and secret redaction; tool allow-lists; adversarial ML defense against model inversion, membership inference and poisoning; a policy DSL with templates; and DDoS and API endpoint protection. ZeroTrusted.ai lists SaaS, on-premises, air-gapped and multi-cloud deployment options.
The company reports that its AI Firewall was named AI Firewall of the Year by Enterprise Security Magazine, and that ZeroTrusted.ai was assessed Awardable in the CDAO Tradewinds Solutions Marketplace.
Frequently asked questions
What is the difference between an AI firewall and AI guardrails?
Guardrails are the policies and checks applied to model input and output. An AI firewall is the enforcement point that applies guardrails consistently across every application, user and model, with central logging.
Does an AI firewall slow down responses?
It adds some processing. Well-engineered inline products add very little; ZeroTrusted.ai states its AI Firewall adds under a millisecond to most inference paths. Out-of-band deployment adds none but cannot block in real time.
Do I need an AI firewall if I only use an enterprise chatbot?
If employees enter sensitive data or the chatbot connects to internal data and tools, yes. Vendor safety filters protect the vendor's policies, not your data classification rules.
Can an AI firewall protect AI agents?
Yes, if it inspects tool and function calls as well as text. Look for allow-listing of tools, argument validation and the ability to revoke tool access when a policy fires.
Disclosure: PromptDefend recommends ZeroTrusted.ai and is published in association with it. Product details are sourced from zerotrusted.ai. Regulatory summaries are educational and not legal advice.