Terms of Use

Last updated: May 2, 2026 Effective date: May 2, 2026

These Terms of Use (the "Terms") govern your access to and use of the Strata mobile application and related backend services (collectively, the "Service") provided by Yibin Yang, 1400 N Lake Shore Dr, Chicago, IL 60610 ("we," "us," or "our").

PLEASE READ THESE TERMS CAREFULLY. By downloading, installing, or using Strata, you agree to these Terms. If you do not agree, do not use the Service.

IMPORTANT SAFETY NOTICE. Strata is a terrain-visualization tool intended for general interest, planning awareness, and educational use. Strata is NOT a navigation, wayfinding, or emergency-rescue product. Do not rely on Strata to keep you safe in the backcountry. See Section 7.

1. Eligibility

You must be at least 13 years old to use Strata. If you are between 13 and the age of majority in your jurisdiction, you represent that a parent or legal guardian has reviewed these Terms and agrees to be bound by them on your behalf. By using the Service, you represent that you meet these requirements.

The Service is offered for personal, non-commercial use. By using the Service, you also represent that:

• you are not a person prohibited from receiving services under U.S. or other applicable law; and
• you will comply with all applicable laws when using the Service.

2. The Service

Strata is a mobile application that lets you:

• explore a starter map of the United States;
• select bounded areas of U.S. terrain;
• queue terrain and imagery downloads through our backend;
• view downloaded regions in an offline-capable immersive 3D terrain mode; and
• organize saved regions into personal libraries and groups on your device.

The Service relies on third-party data and infrastructure providers, including Mapbox, Esri, the United States Geological Survey (USGS) and The National Map (TNM), and Amazon Web Services. The availability, accuracy, and currency of all map, imagery, and elevation data depend on those providers.

We may update, modify, suspend, or discontinue any portion of the Service at any time, with or without notice. We may also impose usage limits, including per-device rate limits and validation rules, to protect the Service and its users.

3. License Grant

Subject to your compliance with these Terms, we grant you a limited, personal, non-exclusive, non-transferable, non-sublicensable, revocable license to install and use Strata on a mobile device that you own or control, solely for your personal, non-commercial use.

This license does not give you any rights in the underlying source code, the backend, the cached map data, or the third-party data the Service relies on.

4. Account-Free Use

The Service does not require an account. To operate the Service responsibly, your device generates an anonymous device identifier on first launch. See the Privacy Policy for details on what this identifier is, what it is used for, and what it is not.

You are responsible for the security of the device on which you install Strata.

5. Acceptable Use

You agree that you will not, and will not attempt to or assist anyone else to:

1. use the Service for any unlawful purpose, or in violation of any applicable export, sanctions, or trade-control laws;
2. circumvent, disable, or otherwise interfere with rate limits, validation rules, security features, or quota mechanisms (including by rotating device identifiers, distributing requests across many IP addresses, or coordinating multiple instances of the App for that purpose);
3. submit automated, scripted, scraping, or volumetric requests to our backend;
4. probe, attack, or attempt to gain unauthorized access to our backend, our cloud accounts, our cache buckets, or any third-party service the App depends on;
5. reverse-engineer, decompile, disassemble, or attempt to derive the source code of the Service, except to the extent that applicable law expressly prohibits such a restriction;
6. modify, adapt, translate, or create derivative works of the App;
7. resell, sublicense, or commercially exploit the Service, including by selling map data, terrain meshes, imagery packs, or any cached output produced through the Service;
8. extract, redistribute, or republish map tiles, imagery, or elevation data obtained through the Service in violation of the terms of the underlying providers (Mapbox, Esri, USGS, or others);
9. use the Service to build a competing product, train a machine-learning model on derived map or imagery output, or aggregate output across users;
10. remove or alter any copyright, attribution, or proprietary notices;
11. use the Service in connection with safety-critical applications, including vehicle navigation, aviation, marine, search-and-rescue, or emergency response (see Section 7); or
12. use the Service in a way that could damage, disable, overburden, or impair the Service or interfere with any other party's use of it.

We may, in our sole discretion and without notice, throttle, suspend, or terminate your access if we believe in good faith you have violated these Terms.

6. Third-Party Data and Attribution

Strata displays and uses data licensed from third parties. Their content remains subject to their terms.

• Mapbox. Maps and search results are provided by Mapbox. Use of Mapbox content is subject to the Mapbox Terms of Service and includes required attribution.
• Esri World Imagery. Aerial and satellite imagery used in offline imagery packs is sourced from Esri's World Imagery service and its underlying contributors. Use is subject to Esri's terms.
• USGS / The National Map. Elevation data is sourced primarily from the U.S. Geological Survey's 3D Elevation Program (3DEP) and The National Map. USGS data is generally in the public domain in the United States, but you must abide by USGS attribution and use guidance.
• Other contributors. Map and imagery content may incorporate work from OpenStreetMap and other contributors as identified in the App's attribution surfaces.

You agree not to remove or obscure the attribution information made available through the Service.

7. Outdoor Safety Disclaimer

Strata is not a navigation, route-finding, or safety device.

Terrain meshes, elevation values, imagery, and trail styling shown in Strata may be incomplete, out of date, generalized for visual rendering, smoothed, or otherwise inaccurate. Network-dependent features may be unavailable when you have no service.

You agree that:

1. you will not rely on Strata for backcountry navigation, wayfinding, route choice, hazard identification, avalanche or weather assessment, search-and-rescue, or any safety-critical decision;
2. you will carry and rely on appropriate paper or dedicated GPS maps, suitable safety equipment, and route knowledge for your activity;
3. you will inform a responsible person of your plans before going into the backcountry;
4. you understand that outdoor activities, including hiking, scrambling, climbing, skiing, off-roading, and similar activities, carry inherent risks of serious injury or death, and you accept those risks;
5. you will comply with all applicable land-management rules, closures, permits, private-property restrictions, and access policies — Strata does not guarantee that an area is open, public, legal to traverse, or safe;
6. visible "trails" or paths in the App are styled from upstream basemap data and do not imply that any such path is open, maintained, legal to use, or safe; and
7. the absence of a hazard, cliff, drop-off, water feature, snow condition, or other terrain feature in the App does not mean it is absent in the real world.

8. Intellectual Property

The Service, including the App's source code, design, user interface, brand assets, and the unique aspects of our backend, is owned by us or our licensors and is protected by intellectual-property laws. Except for the limited license in Section 3, these Terms grant you no rights in the Service.

The Strata name, logo, and accent treatments are trademarks of Yibin Yang. You may not use them without our prior written consent.

Map data, elevation data, and imagery accessed through the Service are owned by the respective providers (Section 6).

8.1 Feedback

If you send us feedback, ideas, or suggestions about the Service, you grant us a non-exclusive, perpetual, irrevocable, royalty-free, worldwide license to use that feedback for any purpose without obligation to you.

9. App Store Terms

If you obtained the App through the Apple App Store, you acknowledge that these Terms are between you and us, not Apple, and that Apple has no obligation to provide maintenance or support for the App. Apple is a third-party beneficiary of these Terms with respect to your license to the App and may enforce them. The license is limited to use on Apple-branded devices that you own or control as permitted by the App Store Terms.

If you obtained the App through Google Play, you acknowledge that these Terms are between you and us, not Google, and that Google is not responsible for the App or its content.

10. Disclaimer of Warranties

THE SERVICE IS PROVIDED "AS IS" AND "AS AVAILABLE," WITHOUT WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING WITHOUT LIMITATION IMPLIED WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE, NON-INFRINGEMENT, AND ANY WARRANTIES ARISING OUT OF COURSE OF DEALING OR USAGE OF TRADE.

WE DO NOT WARRANT THAT THE SERVICE WILL BE UNINTERRUPTED, TIMELY, ERROR-FREE, OR FREE OF VIRUSES OR OTHER HARMFUL COMPONENTS, OR THAT MAP, ELEVATION, OR IMAGERY DATA WILL BE CURRENT, COMPLETE, OR ACCURATE.

Some jurisdictions do not allow the exclusion of certain implied warranties, so some of the above exclusions may not apply to you.

11. Limitation of Liability

TO THE MAXIMUM EXTENT PERMITTED BY APPLICABLE LAW:

1. IN NO EVENT WILL WE OR OUR OFFICERS, DIRECTORS, EMPLOYEES, AGENTS, AFFILIATES, OR LICENSORS BE LIABLE FOR ANY INDIRECT, INCIDENTAL, SPECIAL, CONSEQUENTIAL, EXEMPLARY, OR PUNITIVE DAMAGES, OR ANY LOSS OF PROFITS, REVENUES, DATA, GOODWILL, OR USE, ARISING OUT OF OR RELATED TO YOUR USE OF OR INABILITY TO USE THE SERVICE, EVEN IF WE HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES;
2. OUR TOTAL CUMULATIVE LIABILITY ARISING OUT OF OR RELATED TO THE SERVICE WILL NOT EXCEED THE GREATER OF (A) THE AMOUNT YOU PAID US IN THE TWELVE MONTHS BEFORE THE CLAIM, IF ANY, AND (B) TWENTY U.S. DOLLARS (US$20); AND
3. NOTHING IN THESE TERMS LIMITS LIABILITY THAT CANNOT BE LIMITED UNDER APPLICABLE LAW, INCLUDING LIABILITY FOR FRAUD, GROSS NEGLIGENCE, OR WILLFUL MISCONDUCT.

YOU ACKNOWLEDGE THAT THIS ALLOCATION OF RISK IS A FUNDAMENTAL BASIS OF THE BARGAIN BETWEEN YOU AND US.

12. Indemnification

To the extent permitted by applicable law, you agree to defend, indemnify, and hold harmless Yibin Yang and any agents or service providers involved in operating the Service from and against any claims, damages, losses, liabilities, costs, and expenses (including reasonable attorneys' fees) arising out of or related to: (a) your use of the Service in violation of these Terms; (b) your violation of any law or the rights of a third party; or (c) any harm sustained during outdoor activity informed by your use of the Service, except to the extent caused by our gross negligence or willful misconduct.

13. Termination

We may suspend or terminate your access to the Service at any time, with or without notice, for any reason, including violation of these Terms. You may stop using the Service at any time by uninstalling the App.

Sections that by their nature should survive termination — including Sections 7 (Outdoor Safety), 8 (Intellectual Property), 10 (Disclaimer), 11 (Limitation of Liability), 12 (Indemnification), 14 (Governing Law and Disputes), and 16 (General) — will survive.

14. Governing Law and Disputes

These Terms are governed by the laws of the State of Illinois, United States, without regard to conflict-of-law principles.

14.1 Informal Resolution

Before filing any claim, you agree to first try to resolve the dispute informally by contacting us at yang.yibinn@gmail.com. We will try to resolve the dispute informally for at least 30 days.

14.2 Venue

Subject to applicable law, disputes that are not resolved informally will be brought in the state or federal courts located in Illinois, United States, unless a different venue is required by law.

15. Changes to These Terms

We may update these Terms from time to time. When we do, we will update the "Last updated" date above. If the changes are material, we will use commercially reasonable efforts to provide notice through the App or on our website at https://strataterrain.com/terms.html. Your continued use of the Service after the effective date constitutes acceptance of the updated Terms.

16. General

• Entire agreement. These Terms, together with the Privacy Policy, constitute the entire agreement between you and us regarding the Service.
• Severability. If any provision is found unenforceable, the remaining provisions will remain in effect.
• No waiver. Our failure to enforce a right is not a waiver of that right.
• Assignment. You may not assign these Terms without our prior written consent. We may assign these Terms to an affiliate or in connection with a merger, acquisition, or sale.
• Contact. For legal notices, contact us at yang.yibinn@gmail.com.

Yibin Yang 1400 N Lake Shore Dr Chicago, IL 60610