Terms of service

Version 1.0, last updated 2026-10-05. Published by the developer of Nimbus.

Nimbus is an open-source study app released under the MIT licence. You can use it, read it, change it and ship your own version. The app is free and works with no account; one optional subscription, Nimbus Pro, pays for the parts that run on a server. In exchange it comes with no warranty and no guarantee that it will not lose your work, so keep your own backups.

1. Who you are agreeing with

These terms are between you and the developer of Nimbus, an individual developer. Contact: hello@getnimbus.org.

The sale itself is made by Stripe, not by us. Nimbus Pro is sold through Stripe Managed Payments, which means a Stripe company is the seller of record for your purchase: it takes the payment, calculates and pays the sales tax, VAT or GST, issues the receipt and the invoice, handles any dispute, and can issue a refund. You will see the purchase described as Sold through Link and your statement will read LINK.COM followed by our name. Stripe's own terms govern that sale. These terms still govern the software and the service you are buying access to, and the commitments in them and in the refund policy are ours and are not reduced by it.

If you subscribed before version 1.5 of these terms, that subscription continues under the previous arrangement, in which we were the seller and Stripe only processed the payment. Stripe cannot move an existing subscription onto the new one, so for a while both exist. Everything you are entitled to is identical either way.

2. The licence

The Nimbus source code is published under the MIT licence, reproduced in full in LICENSE at the root of the repository and summarised on the notices page. That licence governs the software. Nothing on this page takes away a permission the MIT licence grants you.

You may use Nimbus for anything, including commercially, and you may modify and redistribute it. You must keep the copyright notice and the licence text in any copy you distribute.

3. What Nimbus costs

Nothing. The desktop app is free and has no paid feature, no trial that expires, no advertising, and no account requirement. All six study modes, the cram planner, the focus timer, progress tracking, import, export, and unlimited decks and cards are free on the machine in front of you, permanently.

The pricing page describes a plan called Nimbus Pro, marked as not available. It is not built and cannot be bought. No payment method is integrated anywhere in this project, so there is no way for Nimbus to charge you, by accident or otherwise. If that ever changes it will be a deliberate, announced change with its own terms, and it will not apply retroactively to a copy you already have. See the refund policy.

The sync server is in the same repository under the same MIT licence. You can run it yourself, for any number of your own machines, and pay nothing.

3. What Nimbus costs

The desktop app is free. It has no trial that expires, no feature that stops working after a period of use, no advertising, and no account requirement. All six study modes, the cram planner, the focus timer, progress tracking, import, export, and unlimited decks and cards are free on the machine in front of you, permanently.

Turning a share link off is always free, and so is opening one somebody sent you and taking a copy of the deck. Only creating a link needs a subscription. If yours lapses, every link you made keeps working and you keep the ability to withdraw any of them.

That list does not shrink when something is added to Pro. The AI features are additions, not parts of the free app moved behind a payment: every study mode works exactly as it did without them, importing a Quizlet or Knowt export and pasting your own notes remain free and unlimited, and nothing that worked on your machine before has been taken away or will be.

Nimbus Pro is an optional subscription that covers the parts of Nimbus that cost money to run, because they run on a server rather than on your machine: hosted sync between machines, publishing decks to the public library, creating a share link to one of your decks, and the two AI features, which are asking a question about the card you are studying and generating draft cards from a PDF or a PowerPoint file. You can pay for it monthly or, if this deployment offers it, once.

The price on the pricing page is read directly from Stripe rather than typed into the page, so it is always the real list price and never a figure left behind by an old edit. Two things are added to it at checkout, and both are shown to you in full before you pay: tax, because prices exclude sales tax, VAT and GST, and currency conversion, because Stripe presents the price in your own currency where it can. So the total you are charged can be higher than the figure on the pricing page, and the checkout page is the one that states it exactly. There is nothing else: no setup fee, no per-deck or per-card charge, and no amount that appears later.

The AI features send text to a third party to be processed, which is described in full in the privacy policy. They are optional, they do nothing until you press the button, and a language model can be wrong: the cards it drafts are shown to you to check and edit before anything is added to a deck, and nothing it says changes a card or a schedule on its own. Nimbus makes no warranty that an answer or a generated card is correct, and you should check anything that matters against your own source.

The sync server is in the same repository under the same MIT licence. You can run it yourself, for any number of your own machines, and pay nothing. The subscription buys the hosted service, never the software.

The Class plan on the pricing page is not built and cannot be bought.

3a. The subscription

Billing. Payments are taken by Stripe, on a Stripe-hosted page. Nimbus never receives or stores your card details. Stripe is also the seller of record, as section 1 explains, so the receipt, the invoice and the tax are Stripe's.
You can manage it in two places. Your account page opens the Stripe customer portal, and Stripe's own order management at link.com lists everything you have bought through it. Cancelling in either one cancels it; there is no version of this where you have to find the right one.
It renews at the interval shown at checkout until you cancel. The next renewal date is on your account page and in the app under Settings.
Cancelling is one click from your account page, at any time, with no retention flow. Pro keeps working until the end of the period you have already paid for.
Refunds are covered by the refund policy, which forms part of these terms: a full refund within 14 days of any charge, no reason needed. Because Stripe is the seller, Stripe can also issue one, including on its own initiative if it handles a support request we have not answered.
A failed renewal does not cut you off on the first failure. Stripe retries for several days and Pro keeps working while it does.
If the price changes, an existing subscription is not repriced without notice and a chance to cancel first.
If the hosted service ends, you will be told in advance, billing stops, and you keep every deck. Your data is on your machine the whole time and export always works.

Losing Pro, by cancelling or otherwise, never deletes anything. Sync stops; your decks stay on every machine they are already on and the app keeps working exactly as it does for someone who never had an account.

3b. Lifetime Pro

Lifetime Pro is the same Nimbus Pro, paid for once instead of every month. It is not a different or reduced plan: hosted sync, publishing to the public library and creating share links all work exactly as they do on the subscription, and the two AI features are included on the same daily allowance a subscriber gets, with no separate charge and no credit pack. Nothing renews and no card is kept on file for it.

What “lifetime” means here

It means the lifetime of the hosted Nimbus service, not yours. We say that plainly because the word is used loosely elsewhere and it is the one thing about this purchase that could be misunderstood in a way that costs you money. Buying Lifetime Pro gives you Nimbus Pro for as long as the hosted service described in section 3 is running, with no further payment. It is not a promise that the service will run for any particular length of time, and nobody can honestly make that promise.

What is promised instead is set out in section 9 and applies to Lifetime exactly as it does to a subscription: if the hosted service ends you will be told in advance, you keep every deck, and export keeps working. Your decks are on your own machine the whole time, the desktop app goes on working with no account and no network, and the server is in the repository under an MIT licence so you can run sync yourself at no cost. If the service ends sooner than you could reasonably have expected when you paid, that is covered by If something was broken in the refund policy, which is not limited to 14 days.

The rest of it

Refunds work the same way as for any other charge: a full refund within 14 days of the payment, no reason needed. See the refund policy.
A refund ends it. If the payment is refunded, in full, by us or by Stripe, the account goes back to free. That is automatic, and it is the same thing in reverse: you are not charged for something you have had returned, and you do not keep something you have been refunded for. Nothing is deleted when it happens.
If you already subscribe, buying Lifetime cancels your subscription for you. You do not have to cancel first and you should not: cancelling first is what would leave you without Pro if the purchase did not go through. The cancellation happens once the payment has gone through, and if a renewal was taken in the days before you bought Lifetime, ask and it will be refunded.
Deleting your account ends it, and that is not a refund. Deletion is immediate and irreversible by design, and there is no record left afterwards to restore anything from. If you want a refund, ask for it before you delete the account, not after.
It belongs to the account, not to a person or a machine. It is not transferable and cannot be sold on or split between accounts.
It cannot be bought twice. An account that already has it is refused at checkout rather than charged again.
A later price change does not affect it. You paid once, at the price shown then. If the Lifetime price goes up or down, or stops being offered, what you already bought is untouched.

4. Your account, if you make one

You must be at least 16 years old.
You are responsible for keeping your password to yourself. Nimbus hashes it and cannot tell you what it is.
One person per account. Do not share credentials.
You can delete your account at any time from Settings. It is immediate, it takes your server-side data with it, and it cancels any active subscription for you. You will not be charged again for an account you have deleted, and you do not have to remember to cancel first.

4. Accounts

There are none yet. Nimbus has no hosted service running, so there is nothing to sign in to and no personal data held on any server. The app stores everything in a file on your own computer.

5. Your content stays yours

The decks and cards you write are yours. Syncing them grants no ownership, no licence to publish them, and no right to use them for anything other than storing and returning them to you.

The one exception is a deck you explicitly choose to publish to the public library. Publishing is an action you take deliberately, and it makes that deck readable and copyable by other users. You can unpublish it. Do not publish material you do not have the right to share: copyrighted course material, a textbook's question bank, or someone else's work.

6. What you must not do

Use Nimbus or a sync server to store or distribute unlawful material.
Attack a server you do not own, including attempts to reach another account's data.
Misrepresent a modified build as the official one.
Publish decks to a shared library that infringe someone else's copyright.

An account used for any of the above can be suspended or deleted. On a server you run yourself, that decision is yours to make.

7. No warranty

Nimbus is provided "as is", without warranty of any kind, express or implied, including the warranties of merchantability, fitness for a particular purpose and non-infringement. This is the MIT licence's own wording and it is meant literally.

Concretely: Nimbus may contain bugs, a release may lose data, the scheduler may schedule a card badly, and no part of this project promises you will pass an exam. Keep your own backups. Settings, then "Export everything", writes one file that restores your whole library, and it takes a second.

8. Limitation of liability

To the fullest extent the law allows, the author is not liable for any claim, damage, lost data, lost study time, or other liability arising out of or in connection with Nimbus or its use.

Nothing in these terms limits liability for death or personal injury caused by negligence, for fraud, or for anything else that cannot lawfully be limited. If you are a consumer, you keep every statutory right your local law gives you, and these terms do not override them.

9. Availability

There is no uptime commitment for any hosted service, because the supported configuration is one you host yourself. The desktop app is offline-first and keeps working whether or not any server is reachable, which is the whole point of building it that way.

10. Changes to these terms

These terms may change. The version and date at the top will change with them, and every previous version stays in the repository's git history. A change that materially affects you will not be applied silently; continuing to use a version you already have is always an option, because the MIT licence on that copy does not expire.

11. Governing law

These terms are governed by the law of the jurisdiction in which the author is resident, and you may bring proceedings in your own country of residence if your local consumer law gives you that right.

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