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 3rd launch from Arcjet. View more
Arcjet AI security models
Launching today
Arcjet is launching a family of custom AI security models designed for analyzing AI agent activity: Arcjet Himalia 1, a general purpose prompt injection model, live today for every SDK call that uses prompt injection detection, and specialist versions designed for situations that general models handle badly, Arcjet Thebe 1 for coding agents, and Arcjet Carme 1, for autonomous security agents.
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@davidmytton put it simply: "You can't detect prompt injections with a general-purpose model."
First launched here 2 months ago and loved by the community (Top Product of the Week, featured in the newsletter), @Arcjet keeps the momentum by announcing a family of custom-trained security models designed for analyzing AI agent activity:
Arcjet Himalia 1, a general-purpose prompt injection model (live now)
Arcjet Thebe 1, for coding agents (in early preview)
Arcjet Carme 1, for autonomous security agents (in early preview)
The models are compact classifiers fine-tuned from @Qwen 3-0.6B, so they return a verdict in milliseconds at a fraction of the cost of asking a frontier model.
More details about the benchmark
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What should @Arcjet build/improve/fix from your perspective?
Hey team, a huge milestone today! Arcjet Security Models came to change the AI game and I'm truly sure many founders will take the most of it. Keep it up!!!
a small classifier giving a verdict in milliseconds instead of sending every tool call to a frontier model is hte only way this works at scale, nobody wants to pay frontier prices just to check each prompt
how do you handle false positives with Thebe 1??? coding agents read so much weird stuff from repos and docs, i'd expect a lot of legit content to look like an injection
If Himalia flags a prompt injection inside a tool result mid run, does it block just that tool output or kill the whole agent session?
The distinction between Himalia being live and the specialist models being in preview is useful. Keeping the model version visible with each verdict would help teams compare behavior as those previews develop.