Cliff Terms
What this is
These terms are between Cliff AI, Inc. ("Cliff", "we") and the person who makes a Cliff account ("you"). They cover your account and the free version of the Cliff app: the desktop program, the cliff-cli command-line tool, and their connection to AI agents. Ordering parts through Cliff is covered by the Buyer Terms, and running a shop on Cliff by the Shop Agreement.
If you, or the organization you work for, has a separate written agreement with Cliff (such as an enterprise agreement), that agreement governs wherever it differs from these terms.
You accept these terms when you make your account. You must be at least 16. If you use Cliff for a company, you confirm you may accept these terms for it, and "you" includes that company.
Your account
Give a real email address and keep your password to yourself. You are responsible for what is done with your account and with the devices signed in to it. Tell us at hello@cliff.ai if you think someone else has used it. You can sign a device out, or delete your account, from the app's Settings at any time.
The app
Cliff gives you a personal, non-exclusive, non-transferable right to install and use the app, free of charge, for any lawful work, including commercial work, while you have an account. You do not resell or redistribute the app, or remove its notices. Parts of the app are open source and come with their own licences, listed in the app; those licences apply to those parts.
We may offer paid plans or paid features alongside the free version. We will tell you what something costs before you are charged for it.
The app is an early release. It will change, may contain faults, and may stop working on some computers. It checks for updates and asks you before it installs one. We may require an update when an older version has a serious fault.
What the app sends us, and Privacy Mode
The free version sends us data as you use it. This is how we pay for a free product: what you do in Cliff helps us improve it, train AI models, and build the business.
Unless Privacy Mode is on, the app sends us: usage data (its version, your operating system and type of computer, how long it is open, which commands are run, how long they take and whether they work, errors and crash reports, which simulations run, and how many requests AI agents make); what you write and do (your questions to the app's assistant and its answers, with the commands it ran; the commands run in the app, with their settings; and error messages); and your designs (the designs you open and work on in the app, including their geometry, parameters, history and files).
Privacy Mode is in Settings, on every plan, and is off unless you turn it on. While it is on, the app sends only usage data (unless you also turn usage data off) and your conversations with the app's assistant. Those conversations are sent only so we can check them for uses these terms forbid; each is deleted once checked, unless the check flags it for review. Your designs and the commands you run are not sent while Privacy Mode is on.
You can also turn usage data off in Settings.
Your content and what you allow us to do with it
What you make with Cliff is yours. We do not claim ownership of your designs.
For everything the app sends us while Privacy Mode is off, and everything you choose to send us (bug reports, designs or sessions you share with us), you give Cliff a worldwide, royalty-free, perpetual, irrevocable licence, which we may sublicense and transfer, to store, copy, analyse, modify and use it, and to make works from it, in order to: run, support and secure Cliff; improve Cliff and develop new products; train and evaluate AI models, including models built by or with others; and share, license or sell it to third parties, such as companies that develop AI models, as the Privacy Policy describes.
Turning Privacy Mode on stops new content from being sent and used this way. It does not undo the use of content we already received, including any model already trained on it.
You confirm that you have the right to give us this licence for everything you send.
Export-controlled and confidential designs
The free version is not for designs you may not share with us. With Privacy Mode off, do not open, create or send through it technical data controlled under U.S. export laws (such as the ITAR or the EAR) or similar laws elsewhere; classified information; or designs, files or information that you have promised someone else to keep confidential, or that you otherwise have no right to give us under the licence above.
If you work with such material, turn Privacy Mode on before you open it, or do not use the free version for it. You are responsible for what you send to Cliff and for complying with the laws and agreements that apply to it. Cliff does not check what you send for export control or confidentiality.
Manufacturing checks
Manufacturing checks (the make commands: checks, plans, costs, quotes, tolerance stacks and release packages) run on Cliff's servers. When you or an agent run one, the app sends the geometry of the parts that check names, with their materials, how they are made and the requirements on them, to Cliff's servers, which work it out and send the answer back. Without a connection, and when you are signed out, those checks do not run. What a check sends is covered by "What the app sends us" like the rest of your designs: with Privacy Mode on, it is used only to run the check and then deleted.
AI agents and other programs
You can connect the app to AI agents and assistants you choose, such as Claude, and you can give the app's assistant your own Anthropic API key or Claude plan. What you send to those services goes from your computer to them, under their terms, and they bill you for it. Cliff is not responsible for those services. The app also sends us your conversations with its assistant, as "What the app sends us" describes.
Some simulations can use solvers you install yourself, such as CalculiX or gmsh. They are separate programs under their own licences. Cliff does not provide or support them.
Results
Cliff's models, simulations, checks, estimates and quotes help you design. They are not an engineering approval or a certification, and they can be wrong. Check anything that matters before you rely on it. You are responsible for your designs and for what is built from them.
Use
You use Cliff lawfully. You do not try to break into Cliff's servers or other people's accounts, overload the service, get around limits we set, or copy, scrape or reverse engineer Cliff's services beyond what the open-source licences allow. You follow the export laws that apply to your designs.
Weapons and defense work
You do not use Cliff to design, make or improve weapons, ammunition, explosives, or chemical, biological, radiological or nuclear weapons, or defense articles under the ITAR, or to help anyone else do so, unless you are doing authorized work for the U.S. government or a U.S. defense contractor under a separate written agreement with Cliff that allows it.
Sanctions and restricted parties
You may not use Cliff if you are located in, or ordinarily resident in, a country or region under comprehensive U.S. sanctions (currently Cuba, Iran, North Korea, Syria, and the Crimea, Donetsk and Luhansk regions of Ukraine), if you are on a U.S. government list of restricted or denied parties, or if you act for anyone who is. You do not use Cliff to send anything to such a place or person.
Suspending and ending
We may suspend or close an account that breaks these terms, and we will tell you why unless the law or a safety concern prevents it. You can stop using Cliff and delete your account at any time. The licence you gave us for content we already received, and the sections on results, limits and claims, continue after your account ends.
Limits
The app is provided as it is, without warranties of any kind, to the extent the law allows. Cliff is not liable for lost profits, lost data or indirect damages. Cliff's total liability to you under these terms is limited to the greater of what you paid Cliff for the app in the 12 months before the claim and 100 US dollars. Nothing here limits what the law does not allow to be limited.
Claims caused by your use
You will defend and compensate Cliff for claims, fines and costs that arise from content you send us that you had no right to send, from your breaking export, sanctions or other laws, or from your breaking these terms.
Changes
Cliff may change these terms. Each version is dated; this one is 2026-11-12. If a change is significant, we will tell you by email or in the app before it applies. If you keep using Cliff after that, the new version applies.
General
These terms are governed by the laws of the State of California. Claims under them are brought in the state or federal courts located in California. If part of these terms cannot be enforced, the rest still applies. These terms, with the Privacy Policy and any separate written agreement with Cliff, are the whole agreement between you and Cliff about the app.
Questions go to hello@cliff.ai. Cliff AI, Inc., 355 1st St, Unit S208, San Francisco, CA 94105.