Not during normal use. Your contact records — names, numbers, emails, photos — stay on your device. To improve the app we send a little first-party, anonymous usage data to our own servers: a random per-install ID that isn't linked to your identity, app and iOS version, device model, app language, and aggregate action counts (merges, kept-separates, cleanup edits, contacts and duplicate groups). Never your contacts, and never for advertising or cross-app tracking. The one exception is a bug report: you can choose to attach contacts so we can reproduce an issue, with an option to anonymize the details first — and only when you decide to send it.
Will merges sync to iCloud / Google / Exchange?
Yes — same as any other contact edit on your phone. ContactOne writes through the iOS Contacts framework, so iCloud, Google, and Exchange propagate the merge to your other devices through their normal sync.
What happens if I undo a merge?
The original separate records come back exactly as they were — across all the accounts they belonged to. ContactOne keeps a full record of each merge until you explicitly clear it.
Why is there a subscription if the app is on-device?
Because real human beings maintain and support this app and we need to keep doing that. The free tier is a real free tier — full scans, ten merges — meant to let you see the problem before paying. After that, $9.99/yr (USD) or $4.99/mo keeps the lights on without ads or selling anything.
Can I see and move contacts between accounts?
Yes. The Accounts tab shows each of iCloud, Google, and Exchange on its own — separately, no auto‑merging — so you can see what's actually where. From there you can move any contact (or a selection) to a different account: useful when consolidating, switching jobs, or auditing a sync that's drifted. Moves are on‑device and undo‑able from History, same as merges.
Does it work on iPad and Mac?
iPhone and iPad today — both Dynamic Type and iPad-scale layouts are fully supported. A native Mac build (Designed for iPad) runs on Apple Silicon. No dedicated macOS app is planned — the iPad app on Mac is the path forward.
What languages does it support?
English, French, German, Hindi, Italian, and Spanish — all UI strings localized and name-matching tuned per locale (e.g. German umlaut folding). Want your language supported? Email help@contactone.app and let us know — we add languages based on the requests we hear.
Will it merge two people who just share a phone number?
No — that's exactly the mistake ContactOne is built to avoid. Matching looks at the whole record, not a single shared field, so two coworkers on the same office line (or a couple sharing a landline) stay separate. When it isn't sure, it asks you rather than guessing — and if you mark two people as “keep separate,” it remembers and won't suggest them again.
How do I know a merge won't quietly lose data?
Two ways. First, every original record is preserved and any merge undoes in a single tap, so nothing is ever truly gone. Second, because it's your data on the line, every release ships only after passing 450+ automated tests covering matching, merging, account handling, and undo — so the app you trust with your contacts stays rock-solid.
