Jack Apps/Terms of use

Terms of use

All apps. Last updated 14 September 2026.

These terms cover every app published by Jack Apps, and this website. Installing or using an app means accepting them.

1. Who you are dealing with

These apps are published by Jackson Gathondu, a sole developer, reachable at jacksongathondu@gmail.com. Below, "we" and "us" mean that person, and "the app" means whichever of Vial, Graphable or Birdsmouth you are using.

2. Apple's terms apply as well

The apps are distributed through Apple's App Store, so Apple's Licensed Application End User Licence Agreement applies to your use of them. Where these terms and Apple's standard agreement disagree, these terms govern, except on any point Apple requires its own terms to govern. Apple is not a party to these terms and has no obligation to furnish support for the apps.

3. Your licence

You get a personal, non-transferable, non-exclusive licence to use the app on devices you own or control, for as long as these terms are kept. You may not resell, sublicence, rent out, decompile, reverse-engineer or extract the source of the app, except where the law permits it regardless of this clause.

4. What you may not do with it

• Use it in any way the law where you are does not allow.
• Present its output as professional, medical, engineering, legal or code-compliance advice from us. Section 7 covers this.
• Interfere with the app, or with the App Store purchase mechanism behind it.

5. Purchases

Every payment is taken by Apple through the App Store. We never see your payment details, and we cannot charge you, refund you, or cancel anything on your behalf.

• One-time unlocks are permanent for the Apple ID that bought them, and return on any device signed in to that Apple ID through Restore purchases. They do not renew and cannot lapse.
• Subscriptions, where an app offers one, renew automatically until you cancel them in the App Store, under your account, then Subscriptions. Cancelling stops the next renewal; the period already paid for runs to its end. Restoring a lapsed subscription correctly returns nothing.
• Prices shown inside an app are read from the App Store at the moment of display. They can change for future purchases. A one-time unlock you already bought is unaffected.
• Refunds are handled by Apple under Apple's policy, at reportaproblem.apple.com. We can pass a request on, and we can help you work out whether something is a fault rather than a refund question, but we cannot issue one.
• Free tiers are described in each app's store listing and on its page here. A free tier is not a trial that expires unless the listing says so, and we will not put a previously free capability behind a charge for anyone who already has the app.

6. Your data is yours

What you enter stays on your device. We hold no copy, so there is nothing for us to sell, lose or hand to anyone. Recovery is yours too: if you delete an app or lose a device, your records are gone unless you exported them first. Each app's privacy policy says exactly what it stores, and what little leaves the device.

7. The limits of what these apps claim

Each app performs arithmetic on numbers you supply and shows you the result. It does not know your circumstances, cannot verify your inputs, and has no opinion about what you should do.

• Vial is not medical advice. It makes no claim of diagnosis, treatment, prevention or mitigation of any condition, offers no doses, schedules or drug information, and is no substitute for the judgement of a qualified professional.
• Birdsmouth checks stair results against a code profile you select, and cites the section it used. That is a check, not a substitute for the code in force on your job, for an engineer's design, or for the inspector who signs it off.
• Graphable is a calculator and plotter. We make no claim that any examination board permits it, and it is not a substitute for a device your board allows.

8. Warranty

The apps are provided as they are, without warranty of any kind, express or implied, including merchantability, fitness for a particular purpose and non-infringement. We do not warrant that an app is free of defects, or that its results are correct for your purpose. Some jurisdictions do not allow these exclusions. Where that is so, this section applies only as far as the law permits, and your statutory rights are untouched.

9. Liability

To the fullest extent the law allows, we are not liable for indirect, incidental, special or consequential loss, for lost data, lost profit, or wasted material and work redone, arising out of the use of an app. Where liability cannot be excluded, it is limited to the amount you paid for the app in the twelve months before the claim, which for a free tier is nothing. Nothing here limits liability for death or personal injury caused by negligence, for fraud, or for anything else that cannot lawfully be limited.

10. Changes to an app, and to these terms

Apps change: features are added, and occasionally removed. A one-time unlock you have bought will not be turned back into a paid feature. If these terms change, the date at the top changes with them, and the previous wording is superseded from that date. Continuing to use an app after a change means accepting it. If you do not accept it, stop using the app and delete it.

11. Ending it

You may end these terms at any time by deleting the app. We may end your licence if you breach them materially. Sections 7, 8, 9 and 12 survive the ending.

12. Law

These terms are governed by the laws of Kenya, without regard to conflict-of-law rules, and the courts of Kenya have jurisdiction. If you are a consumer elsewhere, this does not deprive you of the protection of mandatory consumer law where you live, or of the right to bring proceedings there.

13. Contact

jacksongathondu@gmail.com. A person reads it and replies.