Announcement
Introducing CRX-5: Mantle, Core, and Strata
Three new models join CRX-4.1 Surface in CruxAI, along with new controls for how CruxAI responds, a quicker setup, a Usage page, and smoother typing on iPhone.
CruxAI Summary
CruxAI introduces CRX-5, a new model family (Mantle, Core, Strata) alongside CRX-4.1 Surface, simplifying the lineup to four clearly named options. The update adds granular response controls, faster performance, usage tracking, and effort levels for reasoning depth, with free users getting unlimited Surface and limited Mantle access.
Today we’re introducing CRX-5, a new family of models in CruxAI: Mantle, Core, and Strata. Together with CRX-4.1 Surface, they make up a simpler lineup: four models, each named for what it does best, so you can pick the right one without decoding mode names.
We’ve also given you far more control over how CruxAI responds, rebuilt the first-time setup, added a page that shows your usage at a glance, and made CruxAI noticeably smoother to use.
Meet the lineup
From fastest to most powerful:
- CRX-4.1 Surface — fast everyday conversation. Surface is the default for everyone, and it stays free and unlimited on every plan.
- CRX-5 Mantle — advanced reasoning for complex work, like multi-step problems, analysis, code, and writing that needs care.
- CRX-5 Core — deep reasoning for demanding work.
- CRX-5 Strata — our most powerful model, for the hardest work.
The CRX-5 models think before they answer. When you choose one, an effort control appears next to the model picker, from Light to Extra High, so you can trade a little speed for more careful reasoning when a question deserves it. You can switch models at any point in a conversation.
What’s included on each plan
- Free: unlimited CRX-4.1 Surface, plus CRX-5 Mantle with usage limits. Mantle’s limits refill on a rolling five-hour window, with a weekly limit on top. If you reach one, your chat switches back to Surface automatically so you can keep going.
- CruxAI+: unlimited CRX-5 Mantle, CRX-5 Core with a monthly allowance, and CRX-5 Strata with a weekly allowance shared across chat and Site Builder. CruxAI+ is $7.99 a month or $76.99 a year on the web.
In Site Builder, CruxAI+ members can build with any of the four models, with Mantle as the default. Free projects build with Surface.
Goodbye, Fast, Thinking, and Pro
The old mode names are gone. Now you simply choose a model. CRX-3.5 and CRX-3.2 have been retired from CruxAI chat and Site Builder. Your existing conversations still open exactly as before, with a short note on chats that began on a retired model, and new replies use the current lineup.
CruxAI, the way you like it
Settings → CruxAI → How CruxAI responds now gives you real control over every answer:
- Base style: Default, Coder, Writer, Tutor, or Analyst.
- Characteristics: turn length, formality, technical depth, warmth, and headers and lists up or down from the default.
- Custom instructions: tell CruxAI anything else it should know, in up to 1,500 characters. For example: “Use metric units” or “Explain technical ideas like I’m new to coding.”
Your preferences apply to every model and work whether memory is on or off. If you’d set a tone or response length before, it carries over automatically. A request in your message always comes first, and preferences never override CruxAI’s safety rules.
A faster start
Setting up CruxAI now takes three short steps: what to call you and what you’ll use CruxAI for, how it should respond, and your memory and privacy choices, including Personal Context, which stays off unless you turn it on. CruxAI suggests a starting style based on what you’ll use it for, and the conversation starters on your home screen match your interests. You can run setup again anytime from Settings → CruxAI.
Your usage at a glance
The new Settings → Usage page shows how much of each limit you’ve used as a simple percentage, along with when it refreshes. Surface is always unlimited. Your plan and billing details now have their own Plan page.
Smoother all around
Typing is much smoother in long conversations, especially in Safari on iPhone.
CruxAI makes fewer requests when it loads and does less work as you use it.
The Artifacts window now opens and closes reliably, and buttons across the app are cleaner and better aligned.
For developers
The CruxAI Developer API adds two new models: CRX-5 Mantle and CRX-5 Core, priced the same as CRX-4 Think and CRX-4 Pro. Strata is available only in CruxAI. CRX-3.2 Fast was retired on September 30, 2026. Requests that name it now return a model_deprecated error instead of being answered by another model, so switch to CRX-4 Fast. The CRX-3.5 models and CRX-3.2 Diffusion are unchanged. The full catalog is in the developer documentation.
Try it today
CRX-5 is available now at ai.cruxinteractive.com. Open the model picker in the message box to choose Surface, Mantle, Core, or Strata. Questions? Visit the Help Center.
