Privacy Policy
Day Tripper, by Battle Creek LLC · Last updated 14 October 2026
This policy describes what Day Tripper collects, why, where it goes, and how to get rid of it. It describes the app as it actually works today. Where something is planned but not yet built, it says so rather than reserving the right in advance.
What changed on 14 October 2026
- Free access for testers and invited people. If you gave us your email to get free access (as a tester, or from a Day Tripper card), we keep it on a short invite list. When you next use the app, we check your sign-in email against that list, record that your account has free access, and delete your email from the list. We do not store the email on your account. Details under “Account information” below.
What changed on 24 September 2026
Since the version of 25 August 2026, and each described in full below:
- Packing history is new. What you pack is now kept with the general area of the trip (rounded to roughly 10 km), the month and the forecast, and it stays when you delete a trip. It is deleted with your account.
- Community statistics can now be about a place and a season as well as an activity, built from that packing history, with the same protections: no identifiers, and nothing shown until enough separate people are behind it.
- Open-Meteo now receives the place name you type, including while you type it, so the app can suggest places. Before, it received only coordinates.
- If you name an activity yourself, that name can be sent to Anthropic when a list needs filling.
- Sign-in is email and password only. The earlier text mentioned linked social accounts, which the app does not offer.
These took effect in the app before this page was updated, which is not what the “Changes” section below promises. We are sorry for that, and it is why this list is here.
Who we are
Day Tripper is operated by Battle Creek LLC. For any privacy question, or to ask about the data held about you, contact jonah@battlecreek.work.
What we collect
Account information
Signing in is handled by Kinde, an identity provider. Kinde holds your email address and password. We never see your password.
What we store is:
- An identifier Kinde issues for you, which lets us recognise you on your next sign-in.
- A display name, requested once from Kinde when your account is first created. Depending on how you signed up this is a name or an email address. If Kinde returns nothing usable, we store nothing and the app works the same.
- The date your account was created.
- An account identifier of our own.
- Whether your account has free access to features that will later be paid, why (you are a tester, or you were invited from a Day Tripper card), and until when.
Invites by email. If you gave us your email so we could give you free access, it sits on an invite list until it is used. When you next use the app while you are on that list, we ask Kinde for the email you signed in with, compare the two, and if they match we record the free access on your account and delete your email from the list. Your email is not stored on your account either way. If you never sign in, ask us and we will remove it.
What you put in the app
- Kits — the activities you do and the gear you own, including any item names you type yourself.
- Trips — destination, start and end dates, and optionally how you are travelling, where you are staying, and whether you will have laundry.
- Packing lists generated for those trips, the quantities on them, and which items you checked off.
- Packing events — a record of each time you marked something packed, skipped, or always-pack. These are what make your next list better than your last.
- Packing history — what you packed, kept with the general area of the trip (rounded to roughly 10 km), the month, and whether the forecast was wet, cold or hot. It stays when you delete a trip, so what the app learned about packing for a place is not lost with it. It is deleted with your account.
What we do not collect
- No device location. When you name a destination, you type it; the app does not read your location.
- No advertising identifiers, no third-party analytics, no tracking across apps or websites, and no data sold or shared with data brokers.
- No payment information. The app is free and there is nothing to pay for.
- No contacts, photos, calendar, or health data.
Where your data goes
| Recipient | What reaches them | Why |
|---|---|---|
| Kinde | Your sign-in credentials and email | They run the sign-in itself. We hold their identifier for you, not your password. |
| Fly.io | Everything listed above | They host the server and the disk your data sits on, in the United States. |
| Open-Meteo | The place name you type for a destination, including as you type it, and a trip's coordinates and dates — never your name, account, or anything identifying | Finding the place you mean, and weather forecasts so a list can react to the conditions. Our server makes these requests, so your device's address is not sent. |
| Anthropic | The activity (or the name you gave it, if you named it yourself), the trip length, the general forecast, and the generic names of items already on your list — never your name, account, destination, or dates | Filling a gap when you have no history to draw on. Sent only then; a trip backed by one of your kits reaches no model at all. |
| Sentry | When something goes wrong: the error, the code path it happened in, and which page of the app you were on — never your name, account, destination, coordinates, or anything you typed | So we find out the app is broken without waiting for someone to write in. Sent only on a failure; a normal visit sends nothing. |
That is the complete list. There are no other third parties.
When something breaks
If the app or the server hits an error, a report is sent to Sentry so we can find and fix it. The report describes the failure — what went wrong and where in the code — not you.
We strip identifying information before the report leaves us, and we test that we do: sign-in tokens, your account identifier, your name or email, and your trip's destination and coordinates are all removed. If that stripping ever fails, the report is thrown away rather than sent. Nothing is sent when the app is working normally.
Artificial intelligence
Day Tripper is deliberately built so that most lists involve no AI at all. Items are retrieved from your own history and from anonymous community statistics first; a language model is only consulted to fill a genuine gap, which in practice means a brand-new activity you have no history for.
When a gap needs filling, we send a short description of the trip to Anthropic, who run the language model. What is sent is: the activity (for example "hike" — or, for an activity you named yourself, the name exactly as you typed it), the trip length in days, whether the forecast is wet, cold or hot, and the generic names of items already on your list (for example "Socks", "Rain jacket") so the model does not suggest them again.
What is never sent: your name, your email, your account, any identifier, your destination, its coordinates, or your travel dates. The request carries no way to tell one person from another, and Anthropic does not use it to train their models. If you name an activity yourself, that name is sent as you typed it, so keep it to the activity (“Rock climbing”) rather than anything personal.
If that request fails for any reason, the app falls back to the same fixed built-in table it used before — you still get a list.
Community statistics
The app can tell you that other people packed a given item for an activity — and, as it learns, for a general area and time of year. These are built from packing events and packing history across all users, and they are aggregated and anonymous:
- The stored figures contain no user identifiers — only an activity, an item, a rate, and how many people it is based on, plus a rounded area and a season for the place figures.
- A figure is only shown once enough separate people are behind it, so no statistic can point back at an individual.
- Items marked sensitive, any item you created yourself, and any activity you named yourself are excluded entirely. Only the shared, standard vocabulary is counted.
Deleting your account
You can delete your account from inside the app: Account → Delete account. It is immediate and it is not reversible.
Deleting removes your kits, your trips, your packing lists, your packing history, your stored weather lookups, and your account record. Item names you invented are deleted too, unless another person's list already relies on one — in that case the item survives as an anonymous entry with the link to you removed, because deleting it would break someone else's list.
Your contribution to community statistics is not stored against you. It is recalculated from packing events and packing history, and once yours are gone the next recalculation — within about six hours — no longer counts you.
One thing deletion does not do: your Kinde sign-in continues to exist, because it is held by Kinde rather than by us. If you sign in again you get a new, empty account — not your old one back. To remove the sign-in itself, email us at the address above.
How long we keep things
Your data is kept until you delete your account. There is no separate retention period and no archive: deletion is a deletion.
Security
All traffic between the app and the server is encrypted in transit. Every request that touches your data requires a valid sign-in token. Data is stored on an encrypted volume at our hosting provider.
We should be equally clear about the limits: this is a small operation, the database is a single file on a single machine, and we do not claim certifications we do not have.
Children
Day Tripper is not directed at children under 13, and we do not knowingly collect their information. If you believe a child has created an account, contact us and we will delete it.
Your rights
Depending on where you live you may have rights to access, correct, export, or delete your data. Deletion is built into the app. For anything else, email jonah@battlecreek.work and we will respond within 30 days. We will not charge you for it, and we will not treat you differently for asking.
Changes
If this policy changes materially — a new recipient of your data, a new category collected — we will update the date at the top and describe the change in the app before it takes effect.