Runtime security for AI agents and LLMs: Arcjet observes agent behavior, enforces policies before actions run, and audits every decision in code.
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1 / 2Overview
What is Arcjet?
A family of custom-trained security models for coding agents
Arcjet is runtime security for AI agents and LLMs. Instead of filtering traffic at a gateway, it runs inside your code: it observes what your agents do, enforces policies before actions execute, and audits every decision. Its custom-trained AI security models — led by Himalia 1 for prompt injection detection — are built for analyzing agent activity, with specialist models for coding agents and autonomous security agents.
- Custom AI security models for prompt injection and agent behavior
- Observe, enforce and audit every AI agent action
- guard() intercepts tool calls before dangerous actions run
- Rate limiting, bot protection, Shield WAF, email validation and data-loss prevention
- SDKs for Node.js, Python and Go, plus Claude Agent SDK, LangChain and Vercel AI SDK
Individual is $25 a month and Startup is $299 a month, both with a 15-day free trial; after the trial there is a free tier with 10,000 requests a month. Usage is billed per web request ($5 per 1M) and per agent request ($50 per 1M).
Platforms and languages
Arcjet Availability
Platforms
Languages
Capabilities
Arcjet Key Features
AI security models
Custom-trained models detect prompt injection and risky agent behavior, including Himalia 1 for general use and specialist models for coding and autonomous security agents.
Observe, enforce, audit
Watch agent behavior in code, enforce policies before actions execute, and audit every decision.
Guard before action
The guard() call intercepts tool calls and returns a decision, so dangerous actions never run instead of being cleaned up afterwards.
Runtime security building blocks
Rate limiting, bot protection, Shield WAF, email validation and sensitive information detection in one SDK.
Works with coding agents
Supports Claude Code, Codex, Cursor and Muse Code, with SDKs for Node.js, Python and Go.
Best for
Who uses Arcjet?
Developers building AI agents and AI apps
Stop prompt injection and enforce safety policies inside their code
Security teams
Observe, audit and control what autonomous agents do in production
Plans and access
Arcjet Pricing
Freemium
Individual $25/mo, Startup $299/mo; 15-day free trial, then a free tier with 10,000 requests/mo.
Common questions
Arcjet FAQs
How is Arcjet different from a gateway firewall?
Arcjet runs inside your code and checks the local code path before an action executes, while a gateway only sees traffic passing through it.
What does the free tier include?
After the 15-day trial you can move to the free tier with 10,000 requests a month.
What happens if I exceed my usage?
Usage is capped rather than over-billed: requests stop instead of generating extra charges.
Which AI security models does Arcjet offer?
Himalia 1, a general-purpose prompt injection model, is live now; Thebe 1 for coding agents and Carme 1 for autonomous security agents are in early access.
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