ZYRNTOPO
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Terms of Use

Last updated: August 7, 2026

The short version: Use ZYRNTOPO like any other navigation tool — as an aid, not a guarantee. We license you the app; you keep your data on your own device. The core app is free; ZYRNTOPO Pro is optional and unlocks the advanced features — either a one-time purchase that is yours permanently, or a monthly subscription you can cancel at any time — sold through the app store you installed from or a payment provider we name at checkout. Buy it directly from us and you get 14 days to change your mind — see the Refund Policy. 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.

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 ZYRNTOPO application, in any distribution — Android, installable web app (PWA), desktop builds, and any future platform we release ZYRNTOPO 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.

Who Can Use ZYRNTOPO

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.

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 ZYRNTOPO 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:

ZYRNTOPO 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.

ZYRNTOPO Pro, Pricing, and Payments

The model: The core ZYRNTOPO app is free to use, with no account required. ZYRNTOPO Pro is optional and unlocks the advanced features, sold either as a one-time purchase or as a monthly subscription — for example 3D terrain, unlimited offline downloads, true-scale PDF map sheets, viewshed and premium overlays, and the tactical bridges (ATAK, MAVLink). The price and terms shown on the applicable app store listing or checkout page at the time you buy always control over any general description elsewhere on this website.

ZYRNTOPO Pro is tied to a ZYRNTOPO account, so a single purchase unlocks Pro across the app, web, and desktop. Your Pro license is verified on your device and does not require a continuous connection to us; see our Privacy Policy for the account data we hold.

What you are buying. ZYRNTOPO Pro unlocks the Pro features on your ZYRNTOPO account, across every platform we support. There are two ways to buy it, and which one you chose is shown on the checkout page before you pay.

The permanent unlock is a single payment. It is yours for good: it does not expire, nothing renews, nothing is charged again, and there is nothing to cancel. If we ever stop selling ZYRNTOPO or shut down the licence server, a permanent unlock you have already bought keeps working — the app verifies it on your device rather than asking us.

The monthly plan is a subscription. It is charged once a month, automatically, until you cancel it. You may cancel at any time and without giving a reason, from the link in your purchase receipt or by emailing us; Pro then continues to the end of the period you have already paid for and is not charged again. If a payment fails we will retry it for a short period before access ends, so a card that expires does not cut you off immediately. We will tell you before the recurring price changes.

Neither includes any hosted service, storage, or support commitment beyond the app itself, and neither entitles you to future paid products we may release separately. The checkout page states the exact price, currency and total before you pay; that page, at the moment you pay, is what governs.

How payment works. Where a purchase is offered through an app store, it is processed by that store's own billing system — Google Play Billing, the App Store, or the Microsoft Store — and that store is the seller for that transaction. For direct purchases on this website, payment is processed by the third-party provider named on the checkout page, acting as merchant of record: that provider is the seller of record, invoices you, and collects any VAT, GST or sales tax due where you live. We never see or store your card details. Depending on your country, tax may be added at checkout or already included in the displayed price; either way the total is shown before you confirm.

Immediate delivery. A Pro unlock is digital content delivered as soon as payment succeeds. At checkout we ask you to consent to that immediate delivery and to acknowledge what it means for the statutory right of withdrawal in the EU, EEA and UK. That interacts with your cancellation rights — section 4 of the Refund Policy explains exactly how, including when the 14-day statutory right still applies.

Refunds. Our Refund Policy is part of these Terms and sets out the whole picture: a 14-day, no-reason refund on purchases made directly from us; refunds on store purchases handled by Google, Apple or Microsoft under their own rules, because that store took the payment; and your statutory rights, which nothing here reduces. If a refund is issued, the Pro entitlement on the account is revoked — but nothing on your device is touched, and the free app keeps working.

Price changes. We may change what Pro costs, or what it includes, for future purchases. A price change never reaches back to a purchase you already made: what you bought stays unlocked at the price you paid.

Transfers and account closure. You may transfer your Pro license to another ZYRNTOPO account, or close your account and delete its data, from the account page.

We may change ZYRNTOPO Pro's price, the specific features it includes, or the way it is sold, over time. We may also introduce other paid options in the future — for example additional one-time unlocks, or a subscription for any server-hosted, cloud, or relay feature we add after the date of these Terms (such as an optional hosted relay for Team Sync, which today runs only peer-to-peer, over your LAN, or over a mesh). Where a change affects an existing purchase, we'll describe it here and, where required by law or by the applicable app store's policies, notify existing users before it takes effect.

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.

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.

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

ZYRNTOPO 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.

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.

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.

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.

What we never try to exclude. Nothing in these Terms limits our liability for death or personal injury caused by our negligence, for fraud or fraudulent misrepresentation, or for anything else that cannot lawfully be limited. If you are a consumer, you keep every mandatory right your country of residence gives you — including rights in respect of digital content that is faulty, not as described, or not fit for the purpose you told us about — and these Terms apply only so far as they do not cut across those rights. Where a term here conflicts with a mandatory consumer right, the right wins and the rest of these Terms stay in force.

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.

Apple App Store Additional Terms

ZYRNTOPO is not on Apple's App Store yet; an iOS release is planned. From the moment a version ships there, the following additional terms — required by Apple for apps distributed through the App Store — apply to your use of that version, in addition to the rest of these Terms. We will also meet Apple's own requirements for that release, including in-app account deletion under App Store Review Guideline 5.1.1(v) and App Privacy labels that match our Privacy Policy.

Google Play Additional Terms

If you obtained the app through Google Play, your use of it is also subject to Google Play's Terms of Service, and any purchase made there is subject to Google's own billing terms and refund policy — Google is the seller for that transaction and handles refunds, including the 48-hour self-service window described in our Refund Policy.

Where ZYRNTOPO Pro is offered inside the Android app, it is sold in the way Google Play's Payments policy requires for the country you are in — through Google Play Billing, or through an alternative billing or external-offer route where Google permits one. Whichever applies is shown at the point of purchase, along with who takes the payment, before you pay for anything.

You can delete your ZYRNTOPO account, and the data attached to it, at zyrntopo.com/account or from Settings ▸ Account & ZYRNTOPO Pro inside the app, as Google Play's account-deletion policy requires. What that removes and what is kept is set out in the Privacy Policy.

Microsoft Store Additional Terms

The Windows build is currently a direct download from this website (section 15). If we publish ZYRNTOPO to the Microsoft Store, the following apply to the copy you get there, in addition to the rest of these Terms:

Desktop Builds and Direct Downloads

The Windows, macOS-in-future and Linux desktop builds are distributed by us directly from pois.zyrntopo.com/downloads rather than through a store. (Android is distributed both ways: through Google Play and the Amazon Appstore, where those stores' own terms apply to it, and as a signed APK from the same download archive, where this section applies instead.) A few things follow from direct distribution, and you should know them before you install:

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.

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 19) will survive.

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.

If you are a consumer in the EEA or the United Kingdom, that choice of law does not deprive you of the protection of the mandatory law of your country of residence, and you may bring proceedings in the courts of that country. Wherever you are: before filing anything, please email us. Most issues are a misunderstanding or a bug, and both are cheaper to fix than a claim.

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. The version published when you buy or use the Service is the one that applies to that purchase or use — a later change cannot retroactively take away something you already paid for.

Miscellaneous

If any provision of these Terms is found unenforceable, the rest remain in effect. These Terms, together with our Privacy Policy and Refund 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.

Who We Are, and How to Reach Us

ZYRNTOPO is built and published by Grange Dev Group, a software developer based in the State of Washington, United States, and it is Grange Dev Group you are contracting with under these Terms. Where a purchase is made through an app store or a merchant of record, that company is the seller for that transaction, as described in section 4.

One address reaches us for everything — support, billing and refunds, privacy requests, security reports, and reports of abuse in a Team Sync session: