Arcjet vs HiddenLayer

Arcjet vs HiddenLayer

The two products overlap at runtime, where both can inspect prompts and agent behavior and block what policy disallows. HiddenLayer's reach extends earlier in the lifecycle, to the model files you download and the attacks you simulate before release. Arcjet's reach extends further into the application, where policies can use the tenant, plan, amount or recipient that your code passes in, and onto HTTP routes with bot detection, rate limiting and WAF rules.

Arcjet publishes this comparison. Competitor details come from HiddenLayer's public website, AWS Marketplace listing, partner documentation and announcements, reviewed on October 15, 2026.

What is HiddenLayer?

HiddenLayer describes its AISec Platform as "the most comprehensive security platform for AI." It has five areas:

• AI Discovery builds an inventory of agents, models, endpoints and workflows, including shadow AI.
• AI Supply Chain Security scans model artifacts for malware, backdoors and vulnerable dependencies, with lineage and an AI bill of materials.
• AI Attack Simulation runs red teaming aligned to MITRE ATLAS, including system prompt and red team evaluations.
• AI Runtime Security provides inline detection and response for prompt injection, model extraction, unsafe tool use, data leakage and unauthorized agent actions. In March 2026, HiddenLayer added agentic runtime capabilities, including session reconstruction and threat hunting across sessions and tools.
• Agent Harness Security, launched in August 2026, covers coding agents such as Claude Code, Cursor and GitHub Copilot. It inspects prompts, tool calls, shell commands, file edits and repository interactions, and it can block, redact secrets before the model sees them, or steer the agent with corrective context.

HiddenLayer integrates with AI gateways such as TrueFoundry and the Databricks Unity AI Gateway, where runtime returns allow, block or redact verdicts. It offers a Python SDK for its REST API, and it can deploy inside a customer's AWS environment with private networking. HiddenLayer raised a $100 million Series B in September 2026 and works with customers in financial services, government and defense.

What is Arcjet?

Arcjet is an AI agent runtime security platform that discovers the agents running in your organization, enforces policy across every action, prompt and tool call, and keeps the evidence to prove what happened. Arcjet enforces in the path of the action, in code or in the agent's hook, not on the network.

For agents and applications you build, the Arcjet JavaScript, TypeScript, Python and Go SDKs provide guard() for tool calls, queue workers and MCP handlers, and protect() for HTTP routes. Arcjet integrates with 15 agent frameworks, including the Claude Agent SDK, LangChain, LangGraph, Mastra, OpenAI Agents, the Vercel AI SDK, CrewAI and Google ADK. You write Guard policies in Rego or a builder, run them in dry run, and publish them from the Arcjet Console or MCP server.

For coding agents, Claude Code, GitHub Copilot, Cursor, OpenAI Codex and Muse Code call Arcjet from the hooks they already fire, with no SDK and no code change. One Arcjet policy applies across all five agents, installed through managed settings so developers can't remove it without admin access.

Arcjet detectors cover prompt injection, sensitive information, destination threat analysis and token budgets. The same SDK covers bots, rate limiting, Shield WAF and email validation on HTTP routes. The Arcjet Console records every decision, and on the Enterprise plan decisions export to Datadog, Splunk, SentinelOne, Panther and Amazon S3.

How do HiddenLayer and Arcjet differ?

Lifecycle breadth and in-path depth

HiddenLayer's strength is breadth across the AI lifecycle. A team that downloads open models, fine-tunes them and deploys them behind gateways can use one vendor to scan the model files, test the deployed system and watch it at runtime.

Arcjet's strength is depth at the moment an action runs. Because Arcjet runs in the application, a policy can read the same values your code uses to make the call: which customer this is, which plan they are on, which recipient the email is going to, or how many tokens this run has used. That makes it practical to write rules that depend on business context, and to enforce them the same way on tool calls, queue workers, MCP handlers and HTTP routes.

Coding agents

Both products cover coding agents through the hooks each agent provides, and both note that what can be enforced depends on what each agent's hooks support. HiddenLayer names Claude Code, Cursor and GitHub Copilot. Arcjet covers Claude Code, GitHub Copilot, Cursor, OpenAI Codex and Muse Code, and publishes which events are enforced for each agent and what happens if Arcjet doesn't answer.

Which fits: HiddenLayer, Arcjet, or both?

When to choose HiddenLayer

HiddenLayer fits when any of the following apply:

• You download or build models and need to scan model files for malware and backdoors before they run.
• You want red teaming, discovery and runtime detection from one vendor.
• You need to deploy inside your own AWS environment, or you work in a government or defense setting where HiddenLayer already has a footprint.

When to choose Arcjet

Arcjet fits when any of the following apply:

• Rules need application context, such as tenant, plan, amount or recipient.
• You want the same enforcement layer on tool calls, queue workers, MCP handlers and HTTP routes, with bots, rate limiting and WAF rules.
• You need one policy across Claude Code, GitHub Copilot, Cursor, OpenAI Codex and Muse Code.
• You build in JavaScript, TypeScript, Python or Go and want published pricing with a self-serve start.

Using both

HiddenLayer and Arcjet cover different stages, so they can work together. HiddenLayer can scan the models you deploy and red-team the system before release. Arcjet can then enforce the action-level rules that depend on your application's context in production, and on the Enterprise plan its decisions export to SIEMs such as Splunk, where they can sit next to HiddenLayer's detections.

What are the alternatives to HiddenLayer?

• Prisma AIRS from Palo Alto Networks, which includes the former Protect AI products, covers model scanning, red teaming and runtime.
• Noma Security covers agent discovery, access control, red teaming and detection and response.
• Datadog AI Guard evaluates LLM and tool calls inside Datadog's observability platform.
• AI agent security platforms compares the category by where each product enforces.