Your AI agent is
open for attack.
Prompt Shield
fixes that.
You built something you're proud of. Don't let a stranger hijack it with a single message. Prompt Shield protects your AI agent in minutes — no coding required.
You built the agent.
Now someone wants to break it.
Prompt injection is the #1 security risk for AI agents in 2026. It's when someone sends your agent a message designed to make it forget everything you told it — and do whatever they want instead.
Your agent reveals your secrets
Someone asks the right way and your agent hands over your entire system prompt — your business logic, your rules, your prompts.
You don't even know it's happening
Without a log or monitoring, attacks happen silently. By the time you notice, the damage is done.
Your agent goes off-script
A carefully worded message convinces your agent to ignore your rules and say — or do — things you'd never allow.
Fixing it feels technical
Every security tool out there is built for developers. If you're not writing code, you're left unprotected.
Paste. Protect. Done.
Prompt Shield builds a security shield for your agent and delivers it as a block of text you paste into your system prompt. No plugins, no APIs, no developers needed.
Tell Prompt Shield what your agent does
Describe your agent's job in plain English. GuardPost builds a custom defense policy around it.
Run attacks against your agent before anyone else does
Simulate real injection attacks — role hijacks, hidden instructions, encoded payloads — and watch which ones your current setup catches and which it doesn't.
Copy your defense prompt and paste it into your agent
Works with ChatGPT Custom GPTs, Claude Projects, Zapier AI, Make, and any platform with a system prompt field.
Prompt Shield keeps watch
Your audit log tracks every flagged input so you always know when someone tried something — and whether it was stopped.
Simple Pricing For Builders
Start small. Upgrade when you’re ready. Cancel Any time.
Essential
Prompt Shield Essential
Annual Plan
$336 every 12 months
Prompt Shield Essential
Monthly Plan
$25 every month
Advanced
Prompt Shield Advanced
Annual Plan
$336 every 12 months
Prompt Shield Advanced
Monthly Plan
$35 every month
Professional
Prompt Shield Professional
Annual Plan
$336 every 12 months
Prompt Shield Professional
Monthly Plan
$49 every month
Save 20% On Annual Plans
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Save 20% On Annual Plans *
Putting Real Intelligence In AI
"I spent two weeks building my customer support agent and had no idea someone could just tell it to forget everything I programmed. Prompt Shield identified three vulnerabilities immediately." — James M., Solo Founder
"I thought security was something only developers had to worry about. Turns out it's the first thing I should have set up. Prompt Shield made it something I could actually do myself." — Sarah L., Marketing Consultant
"Prompt Shield’s ease of use help me identify five big vulnerabilities in AI agent I was building. It’s great to have the extra protection to make my agents better." — Seth T., Entrepreneur
"After having a self built agent hijacked it was a relief to have a cost effective tool to prevent that from happening again." — Armen G., Consultant
Frequently Asked Questions
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Not at all. Prompt Shield is built specifically for people who aren't developers. You describe your agent, we generate a security block of text, you paste it into your agent's instructions. That's it.
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Any platform that lets you set a system prompt — including ChatGPT Custom GPTs, Claude Projects, Zapier AI, Make, Voiceflow, Botpress, and more. If there's a "system prompt" or "instructions" field, Prompt Shield works there.
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We block the vast majority of known prompt injection attacks — the kind that target customer support bots, content agents, and personal assistants. For agents handling payments, databases, or sensitive systems, we recommend Prompt Shield as a foundation alongside code-level security measures. We'll always tell you exactly what we protect against and where the limits are.
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It's a safe, controlled test. Prompt Shield sends a known attack — like "ignore your previous instructions" or a hidden base64-encoded command — at your agent's defense setup and shows you, step by step, whether it gets blocked and at which layer. Think of it like a fire drill for your agent.
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Yes, any time. Upgrade, downgrade, or cancel from your account settings with one click. No penalties, no locked-in contracts.
