Updated on January 22, 2026
Updated on January 22, 2026
Privacy policy
Summary
At TripStacks, we believe your travel plans should be your business. Because our app is built with a "local-first" philosophy, we do not require any account creation or login, and we do not collect or store any personally identifiable information (PII). All your itineraries and preferences are stored exclusively on your own device; TripStacks has no backend servers and cannot access your saved data. To provide you with personalized travel suggestions, the app allows you to enter prompts, food preferences, and interests which are sent to Google Gemini for processing. While these inputs are used to generate your custom day plans, they are not linked to a persistent user profile.
How Plan Day works
To provide personalized travel suggestions while keeping TripStacks serverless, the app acts as a secure bridge between your local device and Google’s AI infrastructure.
When you request a day plan, the app bundles your specific prompt with the preferences stored on your phone into a single, encrypted request sent directly to the Gemini API.
How the Data Travels
Because TripStacks has no backend, the "logic" of combining your data happens right on your device. Here is the step-by-step technical flow:
Local Compilation: The app takes your current prompt (e.g., "Plan a Saturday in Tokyo") and retrieves your saved food preferences (e.g., "Vegan, loves sushi") and interests (e.g., "Photography, ancient temples") from your device's local storage.
Prompt Engineering: These pieces are combined into a "Structured Prompt." For example: "Act as a travel expert. Plan a day in Tokyo for a user who is Vegan and interested in Photography. The user wants to: Plan a Saturday in Tokyo."
Secure Transmission: This text is packaged into a JSON object and sent via HTTPS (TLS encryption) to Google’s API endpoint.
AI Processing: Google Gemini processes the text, applies its knowledge of the world, and generates a response.
Direct Return: The response is sent back to the app, which renders it on your screen. None of this data ever touches a TripStacks server.
How Sign In With Apple works
We offer Sign in with Apple as an optional way to enable iCloud sync for your TripStacks data. If you choose to sign in, we receive a unique Apple-provided identifier (and, only on first sign-in, your name and/or email if you choose to share it) to recognize your account on this device. Your trips, photos you attach, and stats are stored and synced via your iCloud account using Apple’s iCloud services (Cloud Documents/Files) and are not stored on our servers. You can sign out at any time to stop iCloud syncing; your data remains in your iCloud account and/or on your device unless you delete it.
Summary
At TripStacks, we believe your travel plans should be your business. Because our app is built with a "local-first" philosophy, we do not require any account creation or login, and we do not collect or store any personally identifiable information (PII). All your itineraries and preferences are stored exclusively on your own device; TripStacks has no backend servers and cannot access your saved data. To provide you with personalized travel suggestions, the app allows you to enter prompts, food preferences, and interests which are sent to Google Gemini for processing. While these inputs are used to generate your custom day plans, they are not linked to a persistent user profile.
How Plan Day works
To provide personalized travel suggestions while keeping TripStacks serverless, the app acts as a secure bridge between your local device and Google’s AI infrastructure.
When you request a day plan, the app bundles your specific prompt with the preferences stored on your phone into a single, encrypted request sent directly to the Gemini API.
How the Data Travels
Because TripStacks has no backend, the "logic" of combining your data happens right on your device. Here is the step-by-step technical flow:
Local Compilation: The app takes your current prompt (e.g., "Plan a Saturday in Tokyo") and retrieves your saved food preferences (e.g., "Vegan, loves sushi") and interests (e.g., "Photography, ancient temples") from your device's local storage.
Prompt Engineering: These pieces are combined into a "Structured Prompt." For example: "Act as a travel expert. Plan a day in Tokyo for a user who is Vegan and interested in Photography. The user wants to: Plan a Saturday in Tokyo."
Secure Transmission: This text is packaged into a JSON object and sent via HTTPS (TLS encryption) to Google’s API endpoint.
AI Processing: Google Gemini processes the text, applies its knowledge of the world, and generates a response.
Direct Return: The response is sent back to the app, which renders it on your screen. None of this data ever touches a TripStacks server.
How Sign In With Apple works
We offer Sign in with Apple as an optional way to enable iCloud sync for your TripStacks data. If you choose to sign in, we receive a unique Apple-provided identifier (and, only on first sign-in, your name and/or email if you choose to share it) to recognize your account on this device. Your trips, photos you attach, and stats are stored and synced via your iCloud account using Apple’s iCloud services (Cloud Documents/Files) and are not stored on our servers. You can sign out at any time to stop iCloud syncing; your data remains in your iCloud account and/or on your device unless you delete it.