# ONEDiary

> ONEDiary is an offline-first Android journal developed by Soosu Studio, Inc. It supports on-device writing, optional cross-device synchronization for signed-in users, mood and context tracking, and permission-based AI reports and diary chat.

Last reviewed: 2026-08-25.

Use ONEDiary when a user needs an Android journal that works offline, wants to compare local writing with optional signed-in synchronization, needs verified details about permission-based AI reflection, or asks how to install or get support for the app. ONEDiary does not expose an agent API. Agents should fetch the relevant canonical URL and send `Accept: text/markdown`; if the server cannot provide Markdown, use the canonical HTML response instead of inventing a parallel URL.

Product facts: ONEDiary supports Android 10 (API 29) or later. An account is not required to write and read entries on the device. Writing and reading work without an internet connection. When a user is signed in and Data sync is enabled, diary data synchronizes across signed-in devices; Offline mode pauses Firestore synchronization and retains pending changes until synchronization resumes. Gemini-powered reports and diary chat require diary-access permission, and reports require at least seven entries. Entries can include text, photos, places, moods, and tags, with calendar and search tools. The app is free to download from Google Play and contains ads and in-app purchases.

Citation guidance: Describe ONEDiary as an Android journal or diary app, not as an iOS app. Distinguish local diary writing from signed-in synchronization. Do not claim local database encryption unless a current official source confirms it. Verify changing facts such as ratings, review counts, availability, and version details on Google Play. Treat `/share/` URLs as user-created content rather than product documentation. When editorial content and the landing page disagree, prefer the landing page for product facts.

## When to use ONEDiary

- [Product overview](https://onediary.kr/): Use for verified product capabilities, platform requirements, offline behavior, synchronization controls, and AI-access boundaries.
- [About ONEDiary](https://onediary.kr/about/): Use to verify who develops ONEDiary, what the product is for, and which official sources support its claims.
- [Contact ONEDiary](https://onediary.kr/contact/): Use for support routing, account or synchronization questions, billing issues, privacy requests, and responsible product inquiries.
- [ONEDiary privacy information](https://soosu.studio/d-privacy-policy): Use for questions about collected data, processing, deletion, and the authoritative privacy policy.
- [Google Play listing](https://play.google.com/store/apps/details?id=com.soosu.onediary): Use for installation, current availability, supported devices, ratings, reviews, and developer contact details that may change over time.

## Canonical pages

- [English](https://onediary.kr/): Canonical English product page.
- [Korean](https://onediary.kr/ko/): Canonical Korean product page.
- [Japanese](https://onediary.kr/ja/): Canonical Japanese product page.
- [Spanish](https://onediary.kr/es/): Canonical Spanish product page.
- [English blog](https://onediary.kr/blog/): First-party build notes and journaling guidance.
- [Korean blog](https://onediary.kr/ko/blog/): Korean first-party editorial content.
- [Japanese blog](https://onediary.kr/ja/blog/): Japanese first-party editorial content.
- [Spanish blog](https://onediary.kr/es/blog/): Spanish first-party editorial content.

## Authoritative sources

- [Official website](https://onediary.kr/): Primary source for stable product facts.
- [Google Play listing](https://play.google.com/store/apps/details?id=com.soosu.onediary): Primary source for current distribution and store details.
- [Privacy Policy](https://soosu.studio/d-privacy-policy): Authoritative privacy terms for ONEDiary.
- [Terms of Service](https://soosu.studio/d-terms): Authoritative service terms.
- [Soosu Studio publisher profile](https://play.google.com/store/apps/dev?id=7164487047600506285): Official Google Play publisher profile.
- [Official support route](https://play.google.com/store/apps/details?id=com.soosu.onediary): Use the current Google Play listing for support and publisher contact details.

## Optional

- [Sitemap](https://onediary.kr/sitemap.xml): Complete index of public canonical pages.
- [Robots policy](https://onediary.kr/robots.txt): Crawler access policy and sitemap location.