Please read before you head into the field

Terms of Use

Last updated: July 16, 2026

Navigation aid onlyNot a substitute for training, judgment, or a PLB.
Pricing may evolveCurrent pricing and any future purchases are described below.
Your content, your deviceWhat you create locally stays yours.
Be decent in Team SyncShared sessions are for your group, not abuse.
The short version: Use ZYRN TOPO like any other navigation tool — as an aid, not a guarantee. We license you the app; you keep your data on your own device. If we ever add paid features, purchases run through the app store you installed from (or a payment processor we name at the time) and follow that store's own refund rules. Don't abuse other people in shared sessions. The app is provided "as is," and — because this is a backcountry and search-and-rescue tool — our liability for anything that happens in the field is limited as described below.

1. Agreement to These Terms

These Terms of Use ("Terms") are an agreement between you and Grange Dev Group ("we," "us," "our") governing your access to and use of the ZYRN TOPO application, in any distribution — Android, installable web app (PWA), desktop builds, and any future platform we release ZYRN TOPO on — together with this website (collectively, the "Service"). By downloading, installing, or using the Service, you agree to these Terms. If you don't agree, don't use the Service.

If you are using the Service on behalf of an organization (for example, a search-and-rescue unit or guide service), you're confirming you have the authority to bind that organization to these Terms.

2. Who Can Use ZYRN TOPO

You must be able to form a binding contract in your jurisdiction to use the Service. The Service is not directed at children under 13, and we do not knowingly allow anyone under 13 to use it, consistent with our Privacy Policy. If your region sets a higher minimum age for agreeing to online terms without a parent or guardian, that higher age applies to you.

3. License to Use the App

Subject to these Terms, we grant you a personal, limited, non-exclusive, non-transferable, revocable license to install and use ZYRN TOPO on devices you own or control, for your own lawful personal or organizational field use. This license does not give you any ownership interest in the app.

You agree not to:

ZYRN TOPO makes use of open-source software and open geospatial data (including OpenStreetMap contributors under the Open Database License). Those components remain governed by their own licenses; nothing here restricts rights you separately hold under them.

4. Purchases, Pricing, and Future Payment Features

Where we are today: ZYRN TOPO is currently available at no charge across the platforms we publish it on. We intend to introduce a purchase at some point, and this site may describe that intent (for example, as a one-time purchase). Until a purchase mechanism actually ships, the app remains free to use, and the price and terms shown in the applicable app store listing at the time you install or buy always control over any general description on this website.

We reserve the right to introduce paid features in the future, in one or more of the following forms, and to change which form we use over time:

Any purchase is processed through the official payment system of the store you installed from (such as Google Play Billing or Apple's In-App Purchase system) or, for direct web or desktop distribution, through a third-party payment processor we name at checkout. We do not directly collect or store your payment card details. Purchases are subject to the refund policy of the platform or processor that processed them, in addition to any rights you have under applicable consumer-protection law.

If we introduce a paid feature that changes how an existing purchase works, we'll describe the change here and, where required by law or by the applicable app store's policies, notify existing users before it takes effect.

5. Voluntary Support / Donations

We may offer a voluntary support link (such as Buy Me a Coffee) for users who want to support development. Contributions made this way are voluntary, are not a purchase of any app feature, and are non-refundable except where required by law.

6. Your Content and Local Data

Maps, markers, tracks, notes, gear lists, photos, and other content you create in the app ("Your Content") are stored locally on your device, as described in our Privacy Policy. You retain all rights to Your Content. We don't claim ownership of it, and — because we don't operate a server that stores it — we generally have no ability to access, back up, or recover it on your behalf. Exporting and backing up Your Content is your responsibility.

If you use Team Sync or another sharing feature, Your Content (including your live location while a session is active) is transmitted directly to the other participants you connect with, using the transport that session is configured for (peer-to-peer, your local network, or a mesh/relay bridge). See Team Sync and Peer Location Sharing in the Privacy Policy for how that works.

7. Acceptable Use

Team Sync, chat, and voice messages let you share a session with other people. When you do, you agree not to:

Because Team Sync sessions are peer-to-peer, LAN, or mesh by design, we generally have no visibility into a session's content and cannot moderate it in real time. Leaving a session or declining to share a session code with someone is the immediate way to stop sharing with them. If you believe someone has abused the Service or another user through it, contact us at the address below — we investigate reports and may restrict or terminate access for anyone who violates this section.

8. Not a Safety Device — Read This Before Relying on the App in the Field

ZYRN TOPO is a navigation aid, not a substitute for proper training, sound judgment, or dedicated emergency equipment such as a personal locator beacon (PLB) or satellite messenger. Always carry backup navigation and share your plans before heading into the field.

Map, terrain, and point-of-interest data displayed in the app comes in part from third-party and crowd-sourced sources (including OpenStreetMap contributors and public elevation datasets) and may be incomplete, outdated, or inaccurate. GPS accuracy depends on your device's hardware, sky visibility, and terrain, and can be degraded or lost entirely in canyons, dense forest, or bad weather. Offline maps, 3D terrain, and Team Sync all depend on your device's battery, storage, and hardware working correctly — none of that is guaranteed. You are solely responsible for your own safety, route decisions, and compliance with land-use and permit requirements when using the Service in the field.

9. Third-Party Services

Optional online features connect directly from your device to third-party map, weather, elevation, routing, and search providers, listed in the Privacy Policy. We don't operate those services and aren't responsible for their availability, accuracy, or content. Your use of them may be subject to their own terms.

Google Play and the Google Play logo are trademarks of Google LLC. ATAK, CalTopo, Gaia GPS, Garmin, and Google Earth are trademarks of their respective owners; references to them describe interoperability only and don't imply affiliation, sponsorship, or endorsement.

10. Disclaimer of Warranties

The Service is provided "as is" and "as available," without warranties of any kind, whether express, implied, or statutory, including implied warranties of merchantability, fitness for a particular purpose, title, and non-infringement. We don't warrant that the Service will be uninterrupted, error-free, secure, or that map, elevation, weather, or POI data will be accurate or current. Some jurisdictions don't allow the exclusion of certain warranties, so some of the above exclusions may not apply to you.

11. Limitation of Liability

To the maximum extent permitted by law, Grange Dev Group will not be liable for any indirect, incidental, special, consequential, or punitive damages, or any loss of data, profits, or goodwill, arising from or related to your use of — or inability to use — the Service, including any reliance on the Service while traveling, navigating, or operating in the backcountry or in a search-and-rescue context. This includes damages arising from inaccurate map or terrain data, GPS or connectivity failure, device or battery failure, or the conduct of other users in a Team Sync session.

To the extent we're found liable despite the above, our total liability for any claim relating to the Service is limited to the amount you paid us for the Service in the twelve months before the claim arose, or fifty US dollars if you paid us nothing. Some jurisdictions don't allow these limitations, so some of them may not apply to you.

12. Indemnification

You agree to defend, indemnify, and hold Grange Dev Group harmless from any claim, damage, loss, or expense (including reasonable legal fees) arising from your violation of these Terms, your use of the Service, or Your Content, except to the extent caused by our own violation of applicable law.

13. Apple App Store Additional Terms

ZYRN TOPO is not currently distributed through Apple's App Store. If and when we release a version there, the following additional terms — required by Apple for apps distributed through the App Store — will apply to your use of that version, in addition to the rest of these Terms:

14. Google Play Additional Terms

If you obtained the app through Google Play, any purchase you make is also subject to Google Play's own Terms of Service and refund policy, which govern how that purchase and any refund request are handled.

15. Changes to the Service

We may add, change, suspend, or discontinue any part of the Service — including a feature you rely on — at any time. Because most of the app runs and stores data on your device, we generally can't push a forced update; you control when you update.

16. Termination

You may stop using the Service at any time by uninstalling the app. We may suspend or terminate your access to any online feature (such as Team Sync, POI sync, or a future purchase system) if you violate these Terms, without affecting your ability to use the parts of the app that run entirely on your device. Sections of these Terms that by their nature should survive termination (including Sections 6, 8, 10, 11, 12, and 17) will survive.

17. Governing Law and Disputes

These Terms are governed by the laws of the State of Washington, USA, without regard to its conflict-of-law rules. Any dispute arising from these Terms or the Service will be handled in the state or federal courts located in Washington, and you consent to that venue, except where applicable consumer-protection law in your jurisdiction requires otherwise. Before filing a claim, please contact us — most issues can be resolved directly.

18. Changes to These Terms

We may update these Terms from time to time, including to reflect a new purchase model, a new platform (such as iOS), or a new feature. Material changes will be reflected on this page with an updated date, and where required by law or app store policy, we'll provide additional notice.

19. Miscellaneous

If any provision of these Terms is found unenforceable, the rest remain in effect. These Terms, together with our Privacy Policy, are the entire agreement between you and us regarding the Service, and supersede any prior agreement on the same subject. Our failure to enforce a provision is not a waiver of it.

20. Contact

Questions about these Terms, or a report about abuse in a Team Sync session? Contact us at grangedevgroup@gmail.com.