Arcjet

Secure the AI agents you're building at runtime

Built by Shane O'Connor, Cassie Gatton, David Mytton and 1 other · Paid

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Product Hunt listing

Listing status

430upvotes

Community score

Shane O'Connor, Cassie Gatton, David Mytton and 1 other (Joined Sep 2026)

Founder

Compared against 6 alternatives

Market comparison

Launched on Launch Llama Sep 27, 2026 · #2 of 47 that day

About

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.

Competitors: Predibase, Robust Intelligence, AI Verify, Lakera AI, Rebuff

Launch Llama's Take

Based on Launch Llama data as of November 2026

Arcjet has 430 upvotes, including the votes it received on Product Hunt. It has been listed on Launch Llama since September 2026. 1 Launch Llama member has upvoted it and it has no reviews yet.

Arcjet is a runtime security platform that provides building blocks for detecting prompt injection, authorizing agent tool calls, and redacting sensitive data. Compared with Kastra, which is described as a runtime authorization layer for AI agents, Arcjet's listed features also include blocking bots and abuse on web applications.

Arcjet vs Kastra

Arcjet vs Kastra: side-by-side comparison
	Arcjet	Kastra	Arceris Ai Security Gateway	Jet Admin
What it does	Secure the AI agents you're building at runtime	For AI teams: Kastra enforces authorization policies on Claude, Cursor, and OpenAI agents in sub-1ms so unauthorized tool use and prompt…	AI security gateway that masks PII in real time	For operations and support teams: Jet Admin builds AI agents without code that take action across 200+ tools via Slack, WhatsApp, or Tele…
Pricing	Paid	Freemium	Paid	Freemium
Free plan	No free plan listed	Yes, free plan	No free plan listed	Yes, free plan
Category	Security software	Developer Tools	Automation tools	Developer Tools
Upvotes on Launch Llama	430	398	Not stated	316
Listed on Launch Llama	September 2026	July 2026	November 2026	May 2026

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Key Features

Detect prompt injection in user input and tool outputs
Authorize agent tool calls based on identity and role
Redact sensitive data before model context or third party calls
Control token spending with per-user budget limits
Block bots and abuse on web applications

Use Cases

Integrate Arcjet's prompt injection detection directly into your agent code to block malicious inputs before they reach your LLM
Use Arcjet's tool call authorization to verify which agent actions are allowed before executing them against your backend systems
Call Arcjet's data redaction API within your agent workflows to automatically strip sensitive information before logging or storage
Deploy Arcjet's bot and abuse detection at runtime to identify and block suspicious requests targeting your AI agent endpoints
Embed Arcjet security blocks into your agent initialization to enforce policies across all tool calls and external integrations

Who it is for

Engineering teams building and shipping AI agents into production workflows
Security teams needing visibility and policy enforcement over coding agents like Claude Code, Cursor, and Copilot
Developers adding runtime protection to web apps and APIs using supported SDKs such as Next.js, Express, or FastAPI

Pricing

Individual plan costs $25/month. Startup plan costs $299/month. Enterprise available at custom pricing. Usage fees apply at $5 per 1M web requests and $50 per 1M agent requests. 15-day free trial available.

View Arcjet pricing →

FAQ

Can I book a demo?

Of course! Book a demo with our team.

How does usage-based pricing work?

Any protect() SDK call counts as a web request, billed at $5 per million. Rate limit, filter, and Shield WAF rules are included in that single request. Protecting coding agents and custom agents counts as an agent request, billed at $50 per million.

Are there any request limits?

There are no hard request limits on paid accounts (the trial has usage limits). All protections are billed based on actual usage at the per-unit rates shown in the usage fees table. You only pay for what you use and you can set budget thresholds to avoid surprises. Billing guarantees are available to insure against volumetric attacks - your app will never go down because you hit a limit.

Is there a free plan?

Yes. When the 15 day trial ends, your account continues on a free plan limited to 10,000 requests per month. The limit is a hard stop rather than metered overage, so you are never billed for going over it. Set up billing and choose a plan to lift the cap.

Do you support open source projects?

Yes. Many open source projects use Arcjet on the Individual plan. The Individual plan works well for non-commercial, community-maintained open source projects and includes access to all protections with discounted or free pricing. Reach out to us to discuss how Arcjet can help.

What payment methods do you accept?

We accept all major credit and debit cards on all plans. Enterprise plans can optionally be purchased through an annual contract and paid by ACH/Wire.

Who is behind Arcjet?

Arcjet Labs, Inc. is headquartered in San Francisco and also has an office in New York. We raised a seed round in 2023 and Series A in 2025. We're backed by Andreessen Horowitz, Plural, Seedcamp, and 20+ angel investors. Our CEO, David Mytton, writes the console.dev devtools newsletter.