Terms of Service

Last updated October 17, 2026

1. Agreement

These terms are an agreement between you (and the business you represent) and Model Stack ("we", "us"), the business that runs modelstack-ai.com. By creating an account or using the service, you agree to them and to our Privacy Policy. If you use Model Stack for a business, you confirm you have the authority to bind it.

2. The service

Model Stack takes a request, chooses suitable AI models from several providers, has them work on it, and returns a result. Which models are used, and how many, is our decision and can change at any time. Features may be added, changed or removed.

3. Your account

• Give accurate information and keep your password secret. You're responsible for what happens under your account, including by team members you invite.
• Account owners on the Business plan can invite members and set a monthly spending limit for each. The owner is responsible for the usage of their team. Teams that already had members before the Business plan existed keep them without it.
• Tell us promptly if you think your account has been accessed without permission.

4. Pricing and payment

There are two ways to pay. Either way you see the exact price of a task when it finishes, and an estimate while it runs.

• Pay as you go. No monthly fee. The price of a task is the real cost of the AI calls it made, multiplied by a fixed markup, currently 1.5 times the AI cost.
• Business plan. A fee for each person on your team, currently $20 per person per month, or $18 per person per month if you pay for a year up front. Each person adds $20 of usage to your team's pool each month. Usage past the pool is priced at the AI cost multiplied by a lower markup, currently 1.25 times. Unused included usage does not carry over to the next month.
• How the plan is charged. The first period is charged when you start the plan, and the plan only starts if the charge goes through. It then renews every month, or every year if you chose yearly, and the fee is charged to your saved card. The fee counts the people on your team when each period begins. Someone who joins partway through a period is charged for the part that is left, together with that share of the month's included usage. Removing someone does not refund their seat; it can be reused until the period ends.
• Cancelling. You can cancel the plan at any time. It keeps working until the end of the period you already paid for, is not charged again, and you then go back to pay as you go. Fees already paid are not refunded.
• Free credit. A new account may receive a small amount of free usage once its email address is confirmed. It is spent before anything is billed, has no cash value, is limited to one per account, and we may change the amount, limit it overall, or stop offering it. While you have no card on file, generating video and the live browser are unavailable, and a single task stops sooner.
• Recommendations are free. Questions such as "which model is best for…?" don't cost you anything.
• A card is required once any free credit is used up, and always before you can start a plan or use video or the live browser. It is saved with Stripe. Nothing is charged when you save it.
• How charges happen. Task prices beyond what a plan's included usage or free credit covers add up as unpaid usage on your account. Your card is charged automatically once that reaches $10, and a balance older than a week of 50 cents or more is also charged. Plan fees are charged the same way. Fractions of a cent carry over.
• Limits. Tasks pause if unpaid usage reaches $25, and a single task stops starting new steps once it has spent $5 in AI cost. We can change these numbers, and will apply the change going forward.
• Declined payments. If a charge fails, your account pauses and the amount stays owed. A working card clears it. If a plan renewal could not be charged, the plan ends and you are not billed for the period you could not use.
• Cancelled or failed tasks. If you cancel a task, you still pay for the AI calls already made, because they cost real money. If a task fails before any model finished, there is nothing to pay.
• Refunds. Charges for completed work are generally not refundable. If you think a charge is wrong, contact us and we'll look at it fairly.
• Changing prices. We can change prices, markups and plan fees. A change applies going forward, and a plan period you have already paid for keeps the price you paid.
• Prices shown are in US dollars and may exclude taxes where they apply.

5. What you may do

You may use Model Stack for lawful business purposes. You may not use it to:

• break the law, or infringe other people's rights;
• create malware, run attacks, or help anyone gain unauthorized access to systems;
• harass, defraud or deceive people, or generate content that sexually exploits minors;
• attempt to bypass limits, probe or overload the service, or resell access to it without our written permission;
• violate the rules of the AI providers whose models run your tasks, which also apply to you.

We can pause or end access if we reasonably believe these rules are broken.

6. Your content and AI output

• You keep your rights to what you submit. You give us permission to process it, and to send it to the AI providers involved, solely to run your tasks.
• As between you and us, you may use the results of your tasks as you wish, subject to the law and the AI providers' terms. Similar outputs may be produced for other people, and we can't promise results are unique.
• You're responsible for what you submit, and for having the right to submit it.

7. AI can be wrong

AI models make mistakes. They can state false things confidently, produce flawed code, miss details, or reflect bias. Model Stack uses several models and a check step to reduce this, but it can't remove the risk. Results are provided to assist you. Review them before relying on them, especially for legal, medical, financial, safety-critical or security-critical decisions, and test any code before you run it in production.

8. Connected accounts

If you connect an outside account, such as Google through Plugins, you do so voluntarily and can disconnect at any time. How we handle that data is described in the Privacy Policy.

Websites your agents use

If you let an agent act on a website for you, you are responsible for being allowed to do that: many sites' own terms restrict automated use, and a site may suspend or ban your account there for it. We can't promise it will work, keep working, or avoid that outcome, and we aren't responsible for what the site does. Only use it on accounts that are yours.

The Browser page and "Browse the web" let Model Stack open any public website in a private browser on our servers. Don't use it to break a website's rules or the law, to collect other people's personal data, to harass or spam, to get around a site's security or sign-in, or to buy things or send messages for others. We may limit or stop its use if it is abused. Pages it visits are shown to the AI helping with the request, so don't ask it to open pages with information you wouldn't want an AI company to see.

9. Availability

We work to keep the service running, but we don't promise it will always be available or error-free. It depends on third-party providers, and an outage at one of them can affect your tasks. We may suspend the service briefly for maintenance.

10. Ending your account

You can stop using Model Stack at any time. To close your account, contact us at modelstack44@gmail.com. Amounts you already owe stay payable. We may suspend or end an account that breaks these terms, is unpaid, or puts the service or other people at risk.

11. Disclaimers and liability

The service is provided "as is" and "as available", without warranties of any kind, to the fullest extent the law allows. To the fullest extent the law allows, we aren't liable for indirect, incidental, special or consequential damages, or for lost profits, revenue or data, and our total liability for any claim relating to the service is limited to the amount you paid us in the three months before the claim arose. Some places don't allow certain limits, so parts of this section may not apply to you.

12. Changes to these terms

We may update these terms. If we make a meaningful change, we'll update the date above and, where it matters, tell you in the app or by email. Using Model Stack after a change means you accept it.

13. Contact

Questions about these terms: modelstack44@gmail.com