Terms of Service

You accept these Terms when the person creating your team ticks the checkbox at sign-up. Each invited user also ticks the checkbox when joining. We record which version was accepted, by whom and when (see ACCEPTANCE.md).

The Service is offered only for business, research or professional purposes, to organizations and to individuals acting in the course of their trade, profession or research. It is not offered to consumers. Users must be at least 18 years old. We may refuse or close an account that we reasonably believe is being used as a consumer.

We offer these plans. Current prices, included execution time and limits are shown on our pricing page and, for your team, in GET /v1/license.

A billing period is one month, starting on the day your subscription starts. Included execution time is given for each billing period. Unused included time does not carry over.

We may change prices or plan contents. For paid plans we give team admins at least 30 days' notice by email before a price increase or a reduction in plan contents takes effect, and the change applies from your first billing period that starts after the notice ends.

Order of precedence. If documents conflict, this order applies: (1) an Enterprise agreement; (2) these Terms; (3) the pricing page and GET /v1/license. The pricing page and GET /v1/license describe current prices and limits; changes to them that are adverse to you are subject to the notice in this section.

Subscriptions. Developer and Team are billed monthly in advance, at the start of each billing period, through our payment processor, Stripe. All prices, including plan fees, per-minute rates and top-ups, exclude applicable taxes, which are calculated at checkout. You authorize us, through Stripe, to charge your payment method at the start of each billing period until you cancel. We email a receipt, and a VAT invoice where applicable, for every charge.

Changing plan. A team admin can change plan on the Account page.

• An upgrade takes effect at once. We charge the full price of the new plan, a new billing period starts that day with the new plan's full included time, and the unused part of the fee for your old plan is added to your paid prepaid balance. If the charge for the new plan fails, the plan does not change. The unused part is the old plan's price multiplied by the number of whole days left in the old billing period, divided by the number of days in that period, rounded to the nearest penny.
• A downgrade takes effect at the start of your next billing period. Nothing is charged or credited until then.

What is billed. You are billed for execution time: the time a product spends working on your job, measured to the millisecond. Time in the queue, loading your input and checking answers is never billed. A job that ends without an answer, including a job that is refused, fails, or reaches its time limit before finding a first answer, is not billed, subject to fair use (section 9). A job you stop is billed for the time it ran before the stop.

Order of use for execution time. Execution time is taken from, in this order: (1) included time for the current billing period; (2) promotional credit; (3) paid prepaid balance, at the per-minute rate for your plan.

Prepaid balance. You add to the balance on the Account page. Paid prepaid balance does not expire while your account is open, and one balance covers every product you subscribe to. It can be used only while you have a paid plan; if you cancel, it stays on your account for when you subscribe again. Unused paid balance can be refunded on request as set out in section 7, including if you do not accept an increase in the per-minute rate.

Paying plan renewals from prepaid balance (optional). Plan fees are charged to your payment method. A team admin can instead switch on Pay renewals from prepaid balance on the Account page. While it is on, each renewal is paid from paid prepaid balance first and any shortfall is charged to your payment method. Balance used this way becomes a subscription fee and is not refundable under section 7. It is off by default and can be switched off at any time, with effect from the next renewal.

When time runs out. If no included time, promotional credit or paid balance is left:

• new jobs are refused (402 budget_exhausted) until time is added; and
• a job that is running is stopped when the time runs out. It is billed only for the time it ran, and any partial result is returned if the product can produce one.

We never charge for execution time you have not paid for in advance or authorized through auto top-up.

We show low-balance warnings on the Account page and in API responses, and email team admins, to help you avoid stopped jobs. These warnings are a convenience: you remain responsible for keeping enough time available, and a missed or late warning does not change the rules above.

Auto top-up (optional). Auto top-up is available on paid plans and is off by default. A team admin may switch it on. When switching it on, the admin chooses and confirms:

1. the threshold: the balance below which a top-up is made;
2. the top-up amount: the amount charged each time; and
3. a monthly cap: the most, before tax, that auto top-up may charge in one calendar month (UTC).

By switching auto top-up on, you authorize us to charge your payment method the top-up amount each time your balance falls below the threshold, up to the monthly cap, until an admin switches it off. We will not exceed the cap.

• We email all team admins when auto top-up is switched on or its settings are changed, and a receipt for every automatic charge.
• Any admin can change the settings or switch auto top-up off on the Account page at any time. Switching off takes effect at once; other changes apply from the next top-up.

Failed payments. If a plan payment fails:

• we email the team admins at once;
• new jobs are refused (402 payment_failed) until the payment succeeds;
• jobs already running are stopped at once, as if you had stopped them yourself. Any partial result is returned if the product can produce one, and time they ran after the payment failed is not billed;
• prepaid balance and promotional credit cannot be used meanwhile, but stay on your account;
• if the payment succeeds later, the billing period keeps its original dates and its included time becomes available from then; and
• if the payment is still unpaid 14 days later, the plan ends and is not renewed. You can choose a plan again at any time.

If an automatic top-up fails, we email the team admins and switch auto top-up off until an admin updates the payment method and switches it on again. Jobs continue while time is left.

"Customer Content" means the models, circuits, instances, parameters and other inputs you send us, and the results the Service produces for you.

Ownership. As between you and us, you own your Customer Content. We claim no ownership of it. We own the Service, the Client Software, our solvers and anything we build or learn in improving them.

What we use Customer Content for. We use Customer Content only for these purposes:

1. To run your jobs and show you the results.
2. To fix faults. If a job fails because of a fault on our side, we may keep that job's content until the fault is fixed, and in any case for no more than 90 days, and use it only to find and fix that fault.
3. To improve our solvers and compilers, using de-identified copies (below). A team admin can switch this off at any time.
4. To keep the Service secure and to investigate abuse or breach of these Terms.
5. Where the law requires, for example a court order. Where we are allowed to, we tell you first.
6. For research and publication, only if a team admin explicitly opts in, and only on the terms shown at that opt-in.

We do not sell Customer Content, do not share it with other customers, and do not use it to train general-purpose AI models.

De-identified copies for solver improvement. Unless your team has switched it off, we keep a de-identified copy of the instances and circuits you send. A de-identified copy:

• keeps only the mathematical structure of the problem, such as coefficient matrices, constraint structure, gate sequences and the solver settings used;
• has names, labels, variable names, comments, file names and other descriptive metadata removed;
• is stored apart from your account. It carries an internal reference used only so that we can delete it if you ask, and is not linked to your team for any other purpose;
• is used only inside 4colors, to test, benchmark and tune our solvers and compilers, including training our own models that choose solver settings;
• is never published, sold, or shown to other customers or third parties (other than our hosting providers, which store it for us); and
• is deleted 24 months after the job, or sooner if you ask.

A team admin can switch this off on the Account page. Switching off applies to jobs submitted afterwards. On request to support@4colors-research.com, we delete de-identified copies already kept for your team. Enterprise teams are switched off by default unless their agreement says otherwise.

Retention. Finished jobs and their results are kept for the job retention period, currently 30 days, and then deleted. An uploaded model is deleted once no upload or job has named it for 30 days. De-identified copies follow the rule above, including after your account closes, unless you ask us to delete them. Shortening the job retention period is a change under section 17. Deleted data is removed from backups within 35 days.

Service statistics. We collect and use non-content statistics about jobs, such as input size and density, timings, resource use, settings and error types, to operate, secure and improve the Service. These statistics do not contain your models, circuits or results.

Our license. You grant us a non-exclusive license to host, copy, process, transform and transmit Customer Content only as needed for the purposes in this section.

Your confirmations. You confirm that you have the rights to send us your Customer Content and that it does not include personal data unless we have agreed otherwise with you in writing.

A plain-language summary is at /data-handling. Personal data about your users (for example names and email addresses) is handled under our Privacy Policy.

The fourcolors Python client is proprietary software (LicenseRef-Proprietary), not open source. It is published on PyPI so that it is easy to install. Copies of the unmodified package may be downloaded and redistributed as PyPI's terms allow, but using it with the Service is governed by these Terms.

• Use with the Service. We grant you a non-exclusive, non-transferable, royalty-free license to install, run and copy the Client Software to access the Service under your team's account.
• Your programs. You may write and distribute programs that use the Client Software, provided they install it as a dependency from PyPI (rather than including a modified copy) and each person who uses them with the Service does so under their own 4colors account or as an authorized user of your team.
• Restrictions. You may not modify the Client Software and distribute the modified version, remove our notices, or use the Client Software with a service other than ours, except where the law expressly allows it.
• Third-party components. Optional extras install third-party packages (such as numpy, zstandard, blake3, Qiskit and dimod). Those packages are under their own licenses, not these Terms.
• Updates. We may release new versions. Older versions may stop working with the API after we give reasonable notice.
• Ownership. We own the Client Software and all rights not expressly granted here.
• End. This license ends when your account closes or these Terms end.

• Explore, Developer and Team: the Service is provided on a best-effort basis. We aim to keep it available but do not promise any uptime, response time or queue time. Jobs may wait in the queue when capacity is busy. We may carry out maintenance, sometimes without notice.
• Enterprise: service levels, if any, are those in your Enterprise agreement.
• Early access features, including 4colors Optimizer for Scheduling, are provided as-is for evaluation. They may change or be withdrawn at any time and are excluded from any service level.
• Support is by email at support@4colors-research.com.

Disclaimer. Except as expressly stated in these Terms, the Service and Client Software are provided "as is" and "as available". To the extent permitted by law, we exclude all implied warranties and conditions, including of satisfactory quality, fitness for a particular purpose and non-infringement.

What we never exclude. Nothing in these Terms limits liability for death or personal injury caused by negligence, for fraud or fraudulent misrepresentation, or for anything else that cannot be limited by law.

Excluded losses. Subject to the paragraph above, we are not liable for any of the following, whether direct or indirect: loss of profit, revenue, business, goodwill or anticipated savings. We are not liable for any indirect or consequential loss.

Data. Subject to the paragraphs above, if Customer Content is lost or corrupted through our fault, our only obligation is to use reasonable efforts to restore it from our most recent backup, if one exists. You should keep your own copies of inputs.

Cap. Subject to the paragraphs above, our total liability arising out of or in connection with these Terms in any 12-month period is limited to the greater of (a) the amounts you paid us in that period, including subscription fees and paid prepaid balance, and (b) GBP 100. For the Explore trial and other free use, our total liability is limited to GBP 100.

Your responsibility. You will compensate us for reasonable losses caused by your breach of section 9 or section 13, or by claims that your Customer Content infringes someone else's rights.

• Each party keeps the other's non-public information confidential and uses it only for these Terms. Customer Content is covered by section 8.
• If you send us suggestions or feedback, we may use them without obligation to you. Feedback does not include Customer Content.

• Governing law and courts. These Terms and any dispute about them are governed by the law of England and Wales. The courts of England and Wales have exclusive jurisdiction.
• Entire agreement. These Terms (with the pricing page and GET /v1/license as described in section 4) and any Enterprise agreement are the whole agreement about the Service. You confirm that you have not relied on any statement not set out in them. This does not limit liability for fraud. Our Privacy Policy and the /data-handling page explain how we handle data but do not add to or change these Terms.
• Assignment. You may not transfer these Terms without our consent. We may transfer them to a successor of our business with notice to you.
• Subcontractors. We use subcontractors and service providers, including our payment processor Stripe and our hosting providers, and remain responsible for them.
• Force majeure. Neither party is liable for delay or failure caused by events beyond its reasonable control.
• Severability and waiver. If a part of these Terms is invalid, the rest stays in force. Not enforcing a right is not a waiver of it.
• Third parties. No one other than you and us has rights under these Terms (Contracts (Rights of Third Parties) Act 1999).
• Notices. We send notices to the email addresses of your team admins. You send notices to support@4colors-research.com or by post to our registered office.