The agent harness performance optimization system. Skills, instincts, memory, security, and research-first development for Claude Code, Codex, Opencode, Cursor and beyond.
Arcjet Js
Runtime security for AI apps and agents: prompt injection detection, tool-call authorization, sensitive-data redaction, bot protection, and rate limiting. Drop it into your…
Install
$
npx @arcjet/cli auth loginClaude Code
claude mcp add arcjet-js -- npx @arcjet/cli auth loginCursor / Claude Desktop (mcp.json)
{
"mcpServers": {
"arcjet-js": {
"command": "npx",
"args": [
"@arcjet/cli",
"auth",
"login"
]
}
}
}Install command taken from the project's README or registry entry. Always review code before running it.
README excerpt
Read full README on GitHub →Arcjet - JS SDK
[Arcjet][arcjet] is the runtime security platform that ships in your AI code. Detect prompt injection, authorize agent tool calls, redact sensitive data, and block bots and abuse. Real-time security building blocks you call inside your app, before an action happens.
This is the monorepo containing various [Arcjet][arcjet] open source packages for JS.
Why Arcjet?
Your app's AI features and agents take real actions, calling tools, reading data, hitting APIs. Arcjet runs inside that code and lets you enforce security on each action in real time, then audit what happened
Which package do I need?
Arcjet protects two types of entry points. Pick the right path for your use case:
| Entry point | When to use | Package |
|---|---|---|
| Request protection | HTTP route handlers, API endpoints, middleware — anything with an incoming Request object. |
@arcjet/next, @arcjet/node, @arcjet/bun, etc. |
| Guard protection | AI agent tool calls, MCP server handlers, queue workers, background jobs — anything without an HTTP request. | @arcjet/guard |
Not sure? If you have an HTTP request, use a framework SDK. If you
don't, use @arcjet/guard. You can use both in the
same project.
Getting started
The fastest way to get started is with an AI coding agent. Log in, install a skill, and let your agent handle the rest.
Step 1: Log in with the CLI
npx @arcjet/cli auth login
You can also sign up and manage keys at
app.arcjet.com, or connect
the Arcjet MCP server to your AI
assistant.
Step 2: Install a skill
Skills give your agent the documentation to detect your framework, install the SDK, and wire up request or guard protection rules.
npx @tanstack/intent@latest install
This discovers @arcjet/skills (and @arcjet/guard if installed) from
node_modules without executing package code. Add an allowlist in your app
package.json so only those packages can surface skills:
{
"intent": {
"skills": ["@arcjet/skills", "@arcjet/guard"]
}
}
Load only the skill for the current task, for example
npx @tanstack/intent@latest load @arcjet/skills#protect. Editor hooks from
intent hooks install are convenience, not a security boundary.
The standalone marketplace install (npx skills add arcjet/skills) still
works from arcjet/skills. Prefer the
versioned package when you want skills that match the SDK in node_modules.
You can also use the Arcjet plugin for Claude Code and Cursor, which bundles skills, MCP, and coding rules.
Step 3: Install the package
Similar plugs
Reverse engineer anything with agents, from app behavior down to native binaries.
Fair-code workflow automation platform with native AI capabilities. Combine visual building with custom code, self-host or cloud, 400+ integrations.
Build Agentic workflows, RAG pipelines, with rich AI model and tool support on one collaborative workspace. Deploy on cloud, VPC, or self-hosted, so teams move from prototype…
User-friendly AI Interface (Supports Ollama, OpenAI API, ...)
A cross-platform desktop All-in-One assistant for Claude Code, Codex, OpenCode, OpenClaw, Grok Build & Hermes Agent. Only official website: ccswitch.io