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适用于：指尖3D（Digit 3D）各平台版本 · 生效日期 2026-10-01

一句话版本：本应用不含第三方分析、广告或跟踪 SDK，所有文件都在你的设备上本地处理 —— 你的图纸不会被上传 —— 除非你自己打开「云存储」并手动点了备份。账号是可选的。从本站下载的安装包只有三件事会告诉本站：开始免费试用时登记一个 8 位设备码，好让重装不能把试用重新来一遍（第 4 节）；每次启动拉开屏公告时，捎带报告你在用三套界面中的哪一套、各用了多久、以及这台设备出现过哪几类 Pro 授权（第 2 节）；以及只有你主动登录时才有的账号信息（第 4 节）。Google Play 版不登记试用，也不报告用量；只有你登录账号时，它才把账号信息和 Google Play 的购买凭据发给本站，好让订阅跟着账号走（第 4 节）。不登录、不用云存储，它就不向本站发任何东西。下面是同一件事的完整表述。

1. 概述

指尖3D（以下称"本应用"）是一款在你的设备上本地运行的 CAD 看图与建模工具，由独立开发者Digit 3D提供。我们把隐私做得很简单：本应用不收集、不上传、不共享你的姓名与电话；你的文件默认不会离开这台设备——登录也不会改变这一点：账号只用来记住"权益属于谁"。唯一的例外是「云存储」：它出厂就是关闭的，只有你自己把它打开、并对某个工程手动点了"备份到云端"，那一份工程才会上传（第 3.1 节，可随时删除）。唯一可能涉及个人信息的是：如果你主动选择登录，本站会保存你的邮箱地址；在 Google Play 版里用 Google 账号登录时，还会保存 Google 提供的账号标识（第 4 节，可随时删除）。Google Play 版声明了联网（INTERNET、ACCESS_NETWORK_STATE）权限，供 Google Play 结算库使用，以及在你登录账号、使用云存储时与本站通信；从本站下载的安装包声明了 INTERNET 与 REQUEST_INSTALL_PACKAGES（检查、下载并安装本应用自身的新版本），以及「手机文件扫描」用的存储权限 MANAGE_EXTERNAL_STORAGE／READ_EXTERNAL_STORAGE（只用于在本机找出打得开的图纸与模型，读到的内容不出设备，详见第 2 节）。本应用会主动发给本站的东西只有三样：第 4 节所述的试用登记、第 2 节所述的界面用量（这两样只有从本站下载的安装包才有），以及第 4 节所述的账号（只有你主动登录才有；Google Play 版登录后还包括购买凭据，用来把订阅记到你的账号上）。前两样都只带一个 8 位设备码；三样都不含你的文件。除此之外，无论哪个版本，本应用都不会把你的文件或任何个人信息发送到网络。

2. 我们收集的信息

不含第三方分析、广告或跟踪 SDK。本应用会主动发给本站的记录只有下面这几项。Google Play 版只有「账号」这一项，而且只在你登录后才有；不登录、不用云存储时，它不向本站发任何请求：

试用登记：从本站下载的安装包在你开始免费试用时发送该设备的 8 位设备码，服务器保存「设备码 + 试用开始时间」。详见第 4 节。
账号（只有你主动登录才有）：账号是可选的。从本站下载的安装包不登录也能完整使用 —— 激活码在你的设备上离线验证、永久有效；Google Play 版不登录也能使用免费功能。如果你选择注册/登录，本站会保存：本站签发的 8 位账号号、你的邮箱地址、你的密码（邮箱注册时设的，只存加盐哈希，我们看不到原文）、用 Google 登录时 Google 提供的账号标识、这个账号名下的权益（激活码，或经 Google Play 核实的 Pro/Max 订阅），以及每台已登录设备的设备码、机型（例如"Pixel 8"）与登录会话。存在的理由只有一个：让你换设备时权益能跟着走。详见第 4 节。
界面用量：本应用有三套可互相切换的界面（全能 / 看图 / 简易建模）。从本站下载的安装包每次启动会向本站拉一次开屏公告，这趟请求捎带五样：8 位设备码、此刻在用哪套界面、三套界面各自的累计使用时长、本应用的版本号，以及这台设备出现过哪几类 Pro 授权（试用 / 购买 / 激活码，只有类别，没有金额也没有订单号）。用途有三个：知道三套界面各有多少人在用、有多少人真的付费，以及发现不可能合法出现的授权状态（那是盗版的痕迹）。不含你的文件，不含账号，也不记录你在应用里做过什么。

设备码由系统的 ANDROID_ID 派生，不含姓名、邮箱、电话或任何账号信息；服务器不保存你的 IP 原文（只存加盐哈希）。

反馈看板（网站上的反馈与 Bug，与国内渠道包里「我的 › 意见反馈与 BUG」是同一块看板、同一份数据）是另一回事——那里保存的是你主动写进去的东西：不打开、不提交，就什么都不会发生。

你提交的标题、正文、截图，以及可选的昵称 / App 版本 / 机型，会公开显示在那个页面上，任何拿到网址的人都能看到。请不要把不愿公开的东西写进去。
可选的联系方式不公开，只有开发者在后台看得到，仅用于就这条反馈联系你。
服务器另外保存你 IP 的加盐哈希（用于限流，不保存 IP 原文），以及一串随机生成、存在你本地的标识——它只用来认出「哪几条是你提的」，不含任何身份信息（网页存在浏览器里，App 存在应用私有目录里，两者互不相通，清掉就没了）。
你可以随时自己删除你提的内容，网页上和 App 里都能删，截图一并删除。
只看不提交就什么都不会留下：浏览看板不写入任何记录。

3. 你的文件与数据（仅本地处理）

你打开、导入或创建的图纸/模型文件（如 DXF、STEP、IGES、STL、OBJ、以及本应用的 .mcad 工程），全部只在你的设备上本地处理，不会被上传或分享。唯一的例外见第 3.1 节「云存储」——那件事必须由你亲手开启并逐个点击才会发生。
你的应用设置、工程文件、以及购买/试用状态，保存在你设备的本地存储中（官网版的试用起始时间另有一份登记在本站；登录账号后，你的权益也会记在账号上，见第 4 节）。
你导出的文件（如 PNG、DXF、STEP 等）会保存到你自己选择的设备位置（相册、下载目录或你指定的文件夹）。
卸载本应用即可删除其在设备上保存的应用数据。

3.1 云存储（出厂关闭，需要你自己打开）

云存储让你把工程备份到云端，换手机时取回来。它出厂就是关闭的，而且即使打开了也不会自动上传任何东西——每一份工程都要你在它的长按菜单里点一次「备份到云端」才会上传。云存储属于 Max 订阅，官网版与 Google Play 版规则相同。

只上传本应用的 .mcad 工程。其他格式的文件（DXF、STEP、STL 等）服务端一律不收。工程里内嵌的导入件与贴图会随工程一起上传，因为没有它们这份工程打不开。
存在哪：阿里云对象存储（中国香港地域），私有权限、静态加密，只有你的账号能取。传输全程 HTTPS，文件不经过我们的服务器—— 本站只签发一次性的、限时的上传/下载地址，字节由你的手机与阿里云点对点传输。
我们不看你的文件。不解析、不预览、不用于任何统计或训练。服务器上只记录：文件名、大小、版本号、时间，以及内容的哈希值（用于去重，看不出内容）。
随时可删。在应用的「云端」里长按任一文件即可从云端删除，立即生效。注销账号会一并删除你在云端的全部文件。
关掉开关不会自动删云端已有的备份——那是你的数据，该由你决定什么时候删。想清空就在「云端」里逐个删掉，或直接注销账号。

3.2 团队版（团队账号）

指尖3D 团队版是给学校和公司用的另一个 App，和本应用分开安装，账号互不相通。上面第 3.1 节说的是本应用的个人云存储，那些规则不变；团队版里的账号和文件按下面这样办：

子账号由团队所有者创建。所有者（老师或管理员）给学生、成员建账号，我们只收用户名和可选的显示名，不收手机号和邮箱。所有者本人用邮箱和密码登录，这个邮箱只用来登录、找回密码和发到期提醒。
文件自动同步，所有者能看。子账号创建、导入、修改的文件（不限于 .mcad 工程）会自动同步到团队云空间：阿里云对象存储（中国香港地域），团队所有者能查看。
操作记录。团队版会记录登录（含设备码和机型）、打开、导出、打印等操作，IP 地址只存前三段，供团队所有者查看，保留 1 年后删除。
团队到期以后。先宽限 15 天，一切照常；之后冻结 180 天，成员不能登录，所有者仍可查看、导出；冻结期满，团队的账号、文件和操作记录全部删除，删除前会发邮件提醒所有者。
未满 14 周岁的学生，由学校在开账号前取得其监护人同意（见团队服务协议）。
我们仍然不看文件内容。不解析、不预览、不用于任何统计或训练。子账号的数据由团队（学校或公司）负责管理，我们按团队的委托保管。

4. 账号、应用内购买与试用

账号是可选的（官网版和 Google Play 版都有）。从本站下载的安装包不登录也能完整使用：激活码在你的设备上离线验证、永久有效，跟登不登录毫无关系；退出登录也不会影响本机激活码。Google Play 版不登录也能使用免费功能。账号存在的理由是让权益跟着人走：换了设备，登录同一个账号，权益就跟过来。
怎么登录。用邮箱和密码注册登录。Google Play 版还可以用邮箱验证码登录，或「使用 Google 账号登录」。
登录时会保存什么。本站保存：签发给你的 8 位账号号；你的邮箱地址（邮箱注册时你填的；用 Google 登录时是 Google 提供的邮箱）；你的密码（邮箱注册时设的）；用 Google 登录时，Google 提供的账号标识（一串固定编号，不是你的 Google 密码）；这个账号名下的权益（官网版的激活码，或 Google Play 版经核实的 Pro/Max 订阅）；以及每台已登录设备的 12 位设备码（由系统的 Android ID 派生，不是 IMEI 或序列号）、机型（例如"Pixel 8"，用于让你在设备列表里认出哪台是哪台）和登录会话。密码只存加盐哈希，我们看不到、也无法还原你的原文密码。数据存在本站位于中国香港的服务器上。
用 Google 登录，只留两样。我们只保留 Google 账号标识和邮箱，不保存你的姓名、头像，也不读取通讯录或其它任何 Google 数据。
邮箱只用于两件事：把验证码发给你，以及在你忘记密码或弄丢激活码时找回账号。我们不会用它给你发任何营销邮件，也不会把它给任何第三方。
登录本身不会上传你的任何图纸。账号只记录"权益属于谁、哪几台设备在用"。想把工程放到云端，要另外打开「云存储」并手动备份（第 3.1 节）——那是两件互相独立的事，只登录不开云存储，你的文件一个字节都不会离开设备。
订阅与付款（Google Play 版）。Pro、Max 按月或按年自动续期，经 Google Play 结算。永久买断不再出售；已经买过永久版的，照常可用。付款由 Google Play 处理，本应用不收集、不接触、不存储你的支付信息（银行卡号等），其数据实践适用 Google 的隐私政策。
订阅怎么记到账号上。你登录后，本应用会把 Google Play 给的"购买凭据"发给本站；本站向 Google Play 核实后，把 Pro/Max 记到你的账号上。这样换设备，或在其他设备上登录同一个账号，也能用。本站还会接收 Google Play 发来的续订、取消和退款通知，据此更新你的权益。不登录，购买凭据就不会发给本站。
Google Play 版集成了 Google Play 结算库，结算相关的网络请求由这个库直接和 Google Play 通信；本应用不会借此上传你的任何文件或个人信息。
免费试用的登记（仅从本站下载的安装包）：你点击"开始免费试用"时，本应用会向本站发送该设备的 8 位设备码；本站记下这台设备第一次开始试用的时间并返回。这样做只有一个目的：让"卸载重装"不能把 7 天试用重新来一遍——试用状态存在应用的私有目录里，卸载时被系统一并删除，只靠设备本地分辨不出"新用户"和"刚重装的老用户"。发送的内容仅此一项，不含账号、文件或任何其他信息，服务器也不保存你的 IP 原文（只存加盐哈希）。没有网络时试用照常开始，等联网了再补登记。Google Play 版不做这项登记：它的试用记录存在本机的 Google Play 服务里，不出设备。
怎么删。在「我的 › 账号」里退出登录，就结束了本机会话。同一页底部的「注销账号」会立即彻底删除整个账号：账号号、邮箱、密码哈希、Google 账号标识、设备清单、登录会话、权益记录，以及你在云端的全部文件。不需要联系我们，也不用等人工受理。步骤和邮件删除的方法见「删除账号」页面。
注销账号不会取消 Google Play 订阅。订阅请在 Google Play 的「付款和订阅」里取消，否则会继续扣费。注销也不影响官网版已购买的永久版：激活码照常在你的设备上离线生效，而且会被释放出来，将来还能绑到新账号上。
进不去 App 也能删。用账号绑定的邮箱，或写上 8 位账号号，发邮件到本页底部的邮箱，我们 7 天内处理并回复。服务器每次更新前会备份数据库，备份最多保留 30 天，所以已注销账号的数据最迟 30 天后也会从备份中消失。

5. 权限

本应用仅使用为完成其功能所必需的最小权限：

文件访问：用于打开/保存你主动选择的 CAD 文件（通过系统文件选择器与媒体库，无需额外存储权限）。
Google Play 结算（com.android.vending.BILLING，由结算库自动声明）：用于应用内购买与订阅。
网络（INTERNET、ACCESS_NETWORK_STATE）：Google Play 版声明这两项，供 Google Play 结算库使用，以及在你登录账号、使用云存储时与本站通信；本站下载的安装包只声明 INTERNET，用于检查新版本与下载安装包。
安装应用（REQUEST_INSTALL_PACKAGES）：仅本站下载的安装包声明，用于在你确认后安装刚下载的新版本。
存储（MANAGE_EXTERNAL_STORAGE，Android 10 上是 READ_EXTERNAL_STORAGE）：仅本站下载的安装包声明，只为「手机文件扫描」这一个功能——在你的设备上找出本应用打得开的图纸与模型（DXF、STEP、STL 等）并列出来。Android 11 起，遍历整机的非媒体文件只剩这一条路。扫描完全在本机进行，读到的文件内容与文件名都不会离开设备，也不会发给我们。Google Play 版不声明这两项，那边只走「你自己选文件夹」的方式。

检查更新只是向本站请求一个版本清单文件，不携带账号、设备标识或任何你的数据（会携带设备码的只有第 2 节所述的那两项）；下载新版本就是一次普通的文件下载。你也可以不理会更新提示，改从官网下载页自行安装。

本应用不请求定位、通讯录、相机、麦克风、电话或读取其他应用数据等权限。

6. 第三方共享

本应用不与任何第三方共享数据。除 Google Play 结算（完成你主动发起的购买），以及你选择「使用 Google 账号登录」时由 Google 完成的登录外，本应用不集成任何会收集数据的第三方服务。核实订阅时，本站会把购买凭据发给 Google Play 查询状态。

7. 儿童隐私

本应用面向一般（专业/工程）用户，并非面向 13 岁以下儿童设计，也不会在知情情况下收集儿童的任何个人信息。

8. 数据安全

你的文件与工程保留在你的设备上，不经由我们的任何服务器——登录之后也一样；你自己备份到云端的工程，也是直接传到云端存储，不经过本站服务器（第 3.1 节）。本站服务器上只有第 2 节所述的那几项（设备码 + 时间 + 界面用量，以及你若登录则还有账号号、邮箱、密码、Google 账号标识、权益记录与设备清单），没有你的文件。密码与登录令牌在服务器上都只存哈希（密码还加了盐），所有请求走 HTTPS。服务器位于中国香港。请依靠你设备自身的锁屏、加密等安全机制来保护本地数据。

9. 你的权利

你可随时通过系统的"文件"管理或应用内操作删除你的工程与文件；卸载应用即可清除其本地应用数据。我们持有的只有第 2 节所述的那几项（以及你自己备份的云端工程）。账号可以随时自己注销：在「我的 › 账号」页底部点「注销账号」，账号号、邮箱、密码、Google 账号标识、设备清单、登录会话、权益记录与云端文件会被立即彻底删除，不需要联系我们（见第 4 节）；进不去 App 也可以发邮件请我们删，见「删除账号」页面。注销不会取消 Google Play 订阅，请先在 Google Play 里取消。数据库备份最多保留 30 天，已删除的数据最迟 30 天后也会从备份中消失。账号也可以只删一部分：在同一页解绑某台设备，或直接退出登录。试用记录不挂在账号上，如需删除，把设备码发到下方邮箱即可（删除后该设备可再次开始试用）。

10. 政策变更

若本政策有更新，我们会修改本页面并更新顶部"生效日期"。重大变更将通过应用或商店说明予以提示。

11. 联系我们

如对本隐私政策有任何疑问，请联系：luoyb0812@gmail.com

1. Overview

Digit 3D ("the App") is a CAD viewing and modeling tool that runs locally on your device, provided by the independent developer Digit 3D. Our approach to privacy is simple: the App does not collect, transmit, or share your name or phone number, and by default none of your files leave this device — signing in does not change that: an account only records who holds which licence. The one exception is Cloud Storage: it ships switched off, and a project is uploaded only after you turn it on yourself and tap “Back up to cloud” on that project (section 3.1; deletable at any time). The only personal data involved comes only if you choose to sign in: your email address, plus — if you sign in with Google in the Google Play build — the account ID Google provides (section 4; deletable at any time). The Google Play build declares the INTERNET and ACCESS_NETWORK_STATE permissions, used by Google’s billing library and, when you sign in or use Cloud Storage, to talk to this site; the build downloaded from this site declares INTERNET and REQUEST_INSTALL_PACKAGES (to check for, download and install new versions of the App itself), plus the storage permissions MANAGE_EXTERNAL_STORAGE/READ_EXTERNAL_STORAGE used only by “Scan device for files” (to find drawings and models on your device that the App can open; what it reads never leaves the device — see section 2). The only things the App itself sends to this site are the trial registration in section 4 and the interface usage in section 2 (both only in the build downloaded from this site), and — only if you sign in — the account data in section 4 (in the Google Play build this includes your purchase token, so your subscription is recorded on your account). The first two carry only an 8-character device code; none of the three carries any of your files. Beyond that, in either build, the App never sends your files or any personal information to the network.

2. Information We Collect

No third-party analytics, advertising, or tracking SDKs. The only records the App itself sends to our server are those below. The Google Play build has only the account, and only after you sign in; if you do not sign in or use Cloud Storage, it sends no request to this site at all:

Trial registration: the build downloaded from this site sends this device's 8-character device code when you start the free trial, and the server stores that code plus the time the trial started. See section 4.
Account (only if you sign in): an account is optional. The build downloaded from this site is fully usable without one — your activation code is verified on the device itself, offline, and never expires; the Google Play build’s free features work without one too. If you do register or sign in, this site stores: the 8-digit account number it issued, your email address, your password (the one you set when registering by email, as a salted hash only — we never see the original), the account ID Google provides if you sign in with Google, the licences on the account (activation codes, or Pro/Max subscriptions verified with Google Play), and the device code, model (e.g. "Pixel 8") and sign-in session of each signed-in device. It exists for one reason: so your licence follows you when you change devices. See section 4.
Interface usage: the App has three interchangeable interfaces (Full / Viewer / Simple Modelling). The build downloaded from this site fetches a launch notice from this site at every startup, and that request carries five things: the 8-character device code, which interface you are on right now, how long you have spent in each of the three, the App's version number, and which kinds of Pro authorisation this device has ever had (trial / purchase / licence key — a category only, never an amount or an order number). They are used to see how many people use each interface, how many actually pay, and to spot authorisation states that cannot legitimately occur (a sign of piracy). It carries none of your files, no account, and no record of what you did inside the App.

The device code is derived from the system ANDROID_ID and contains no name, email, phone number, or account; the server does not store your raw IP address (only a salted hash).

The feedback board (Feedback & bugs on this site and “Me › Feedback & bugs” in the direct build are the same board and the same data) is a separate matter — it holds what you deliberately write into it: nothing happens unless you open it and post.

The title, description, screenshots, and the optional nickname / app version / device you submit are shown publicly on that page to anyone who has the link. Please do not write anything there you would not want public.
The optional contact line is not public. Only the developer sees it, in the admin panel, and only to reply about that post.
The server also stores a salted hash of your IP (for rate limiting — the raw address is not stored) and a randomly generated identifier kept locally, used only to recognise which posts are yours. It carries no identity information (the browser keeps one, the App keeps its own in its private storage; the two are not linked, and clearing that storage removes it).
You can delete your own post, screenshots included, at any time — from the web page or from inside the App.
Reading the board records nothing — only posting does.

3. Your Files and Data (Processed Locally)

Drawing/model files you open, import, or create (e.g., DXF, STEP, IGES, STL, OBJ, and the App's own .mcad projects) are processed entirely on your device and are not uploaded or shared. The one exception is Cloud Storage, section 3.1 — which happens only if you switch it on yourself and tap Back up on a specific project.
Your settings, projects, and purchase/trial status are stored in your device's local storage (the build downloaded from this site also registers the trial start time on this site, and once you sign in your licence is also recorded on your account — see section 4).
Files you export (e.g., PNG, DXF, STEP) are saved to a location you choose on your device (gallery, downloads, or a folder you select).
Uninstalling the App removes the app data it stored on your device.

3.1 Cloud Storage (off by default; you switch it on)

Cloud Storage lets you back up projects and get them back on a new phone. It is off when you install the App, and even once switched on it never uploads anything on its own — each project is uploaded only when you tap “Back up to cloud” on that project. Cloud Storage is part of the Max subscription and works the same way in the build downloaded from this site and in the Google Play build.

Only the App’s own .mcad projects are uploaded. Other formats (DXF, STEP, STL, …) are rejected by the server. Imported geometry and images embedded in a project go with it, because the project cannot be opened without them.
Where it is stored: Alibaba Cloud Object Storage (Hong Kong region), private access with encryption at rest, reachable only by your account. Transfers use HTTPS throughout, and the files do not pass through our server — this site only issues one-time, time-limited upload and download links; the bytes go directly between your phone and Alibaba Cloud.
We do not look at your files. They are not parsed, previewed, or used for any statistics or training. The server stores only the file name, size, version number, timestamp, and a hash of the content (used for deduplication; it reveals nothing about the content).
Delete at any time. Long-press any file under “Cloud” in the App to remove it from the cloud, effective immediately. Deleting your account also deletes all of your cloud files.
Switching the feature off does not delete existing backups — that is your data, and it is your call when it goes. Delete them individually under “Cloud”, or delete your account.

3.2 Digit 3D Team (Team Accounts)

Digit 3D Team is a separate app for schools and companies. It is installed separately from this App, and the two do not share accounts. Section 3.1 above describes this App’s personal Cloud Storage, and those rules do not change; accounts and files in the Team app work as follows:

Member accounts are created by the team owner. The owner (a teacher or admin) creates accounts for students or staff. We collect only a username and an optional display name — no phone number and no email address. The owner signs in with an email address and a password; that email is used only for signing in, password recovery, and expiry reminders.
Files sync automatically, and the owner can see them. Files a member creates, imports, or edits (not only .mcad projects) sync automatically to the team’s cloud space on Alibaba Cloud Object Storage (Hong Kong region), where the team owner can see them.
Activity records. The Team app records actions such as signing in (including the device code and model), opening, exporting, and printing. Only the first three parts of the IP address are kept. The team owner can see these records, and they are deleted after 1 year.
After a team expires. First come 15 days of grace, in which everything works as usual. The team is then frozen for 180 days: members cannot sign in, while the owner can still view and export. When that period ends, the team’s accounts, files, and activity records are all deleted; the owner is reminded by email beforehand.
Students under 14: the school gets the consent of a parent or guardian before creating their accounts (see the Team Service Agreement).
We still do not look at file contents. They are not parsed, previewed, or used for any statistics or training. Members’ data is managed by the team (the school or company), and we keep it on the team’s behalf.

4. Accounts, In-App Purchases & Trial

Accounts are optional (in both the build downloaded from this site and the Google Play build). The build downloaded from this site is fully usable without one: your activation code is verified on your device, offline, and never expires — signing in or out changes nothing about it. The Google Play build’s free features work without one too. An account exists for one reason: so your licence follows you — sign in to the same account on another device and your licence comes along.
How to sign in. Register and sign in with an email address and a password. The Google Play build also offers sign-in with a code sent to your email, and “Sign in with Google”.
What we store when you sign in. The 8-digit account number we issue; your email address (the one you register with, or the one Google provides if you sign in with Google); your password (the one you set when registering by email); if you sign in with Google, the account ID Google provides (a fixed ID number — not your Google password); the licences on the account (activation codes in the build downloaded from this site, or Pro/Max subscriptions verified with Google Play); and, for each signed-in device, its 12-character device code (derived from the system’s Android ID — not the IMEI or serial number), its model (e.g. "Pixel 8", so you can tell your devices apart in the list) and its sign-in session. The password is stored only as a salted hash — we cannot see it and cannot recover your original password. This data is kept on our server in Hong Kong SAR, China.
Signing in with Google keeps two things only. We keep the Google account ID and the email address — not your name or profile picture, and we do not read your contacts or any other Google data.
The email is used for exactly two things: sending you verification codes, and recovering the account if you forget your password or lose your activation code. We will never send you marketing email, and never give it to any third party.
Signing in by itself never uploads your drawings. An account records only who holds which licence and which devices are signed in. Putting a project in the cloud requires separately switching on Cloud Storage and tapping Back up (section 3.1) — two independent things: sign in without Cloud Storage and not one byte of your files leaves the device.
Subscriptions and payment (Google Play build). Pro and Max are auto-renewing monthly or yearly subscriptions, billed through Google Play. Lifetime purchases are no longer sold; if you already bought one, it keeps working. Payment is handled by Google Play — the App does not collect, access, or store your payment information (card numbers, etc.), and Google’s privacy policy applies to it.
How a subscription reaches your account. Once you are signed in, the App sends this site the purchase token Google Play issued; this site checks it with Google Play and then records Pro/Max on your account. That way it also works when you change devices, or sign in to the same account on another device. This site also receives Google Play’s renewal, cancellation and refund notices and updates your licence accordingly. If you do not sign in, the purchase token is never sent to this site.
The Google Play build includes Google’s billing library; billing-related network requests go from that library straight to Google Play, and nothing about your files or identity is sent through it.
Trial registration (build downloaded from this site only): when you tap "Try free", the App sends this device's 8-character device code to this site, and the site records and returns the time this device first started its trial. This exists for one reason: so that uninstalling and reinstalling cannot restart the 7-day trial — the trial state lives in the app's private storage, which the system deletes on uninstall, so the device alone cannot tell a new user from one who just reinstalled. Nothing else is sent: no account, no files, nothing more. The server does not store your raw IP address (only a salted hash). If you are offline the trial starts anyway and registers later. The Google Play build does not do this: its trial record is kept by Google Play services on your device and never leaves it.
How to delete it. Sign out under Me → Account to end the session on this device. Delete account, at the bottom of that same page, erases the whole account immediately and permanently: account number, email, password hash, Google account ID, device list, sign-in sessions, licence records, and all of your cloud files. There is no need to contact us and nothing to wait for. The steps, and how to ask by email, are on the Delete your account page.
Deleting your account does not cancel a Google Play subscription. Cancel it in Google Play under Payments & subscriptions, or you will keep being charged. Deleting the account also does not affect a lifetime licence bought for the build downloaded from this site: the activation code keeps working offline on your device, and it is released so you can link it to a new account later.
You can delete it even if you cannot get into the App. Email the address at the bottom of this page from the email linked to your account, or include your 8-digit account number, and we will handle it and reply within 7 days. The server backs up its database before each update and keeps each backup for at most 30 days, so a deleted account’s data is gone from the backups within 30 days at the latest.

5. Permissions

The App uses only the minimum permissions needed for its features:

File access: to open/save the CAD files you actively choose (via the system file picker and media store; no extra storage permission required).
Google Play Billing (com.android.vending.BILLING, declared automatically by the billing library): for in-app purchases and subscriptions.
Network (INTERNET, ACCESS_NETWORK_STATE): declared in the Google Play build for Google’s billing library, and to talk to this site when you sign in or use Cloud Storage. The build downloaded from this site declares only INTERNET, to check for new versions and download the installer.
Install packages (REQUEST_INSTALL_PACKAGES): declared in the build downloaded from this site only, to install a downloaded new version after you confirm it.
Storage (MANAGE_EXTERNAL_STORAGE; READ_EXTERNAL_STORAGE on Android 10): declared in the build downloaded from this site only, for one feature — “Scan device for files”, which lists the drawings and models on your device that the App can open (DXF, STEP, STL and so on). Since Android 11 this is the only way to walk non-media files across the device. The scan runs entirely on your device; neither the file contents nor the file names leave it, and none of it is sent to us. The Google Play build declares neither — there you pick a folder yourself instead.

An update check requests one version manifest file from this site. It carries no account, no device identifier, and none of your data (the only requests that carry a device code are the two described in section 2); downloading a new version is an ordinary file download. You can also ignore the prompt and install from the download page yourself.

The App does not request location, contacts, camera, microphone, phone, or access to other apps' data.

6. Third-Party Sharing

The App does not share data with any third party. Other than Google Play Billing (used to complete purchases you initiate) and, if you choose “Sign in with Google”, the sign-in carried out by Google, the App integrates no third-party services that collect data. To verify a subscription, this site sends the purchase token to Google Play to check its status.

7. Children's Privacy

The App is intended for general (professional/engineering) users. It is not directed at children under 13 and does not knowingly collect any personal information from children.

8. Data Security

Your files and projects stay on your device and never pass through any server we operate — this remains true after you sign in; projects you back up to the cloud yourself also go straight to cloud storage without passing through our server (section 3.1). The only things on our server are the records described in section 2 (a device code, timestamps, interface usage, and — if you sign in — an account number, your email, your password, your Google account ID, licence records, and a device list) — none of your files. Both your password and your sign-in tokens are stored hashed (the password also salted), and all requests use HTTPS. The server is located in Hong Kong SAR, China. Please rely on your device's own security features (screen lock, encryption) to protect local data.

9. Your Rights

You can delete your projects and files at any time via the system Files manager or in-app actions; uninstalling the App clears its local data. The only things we hold are the records described in section 2 (plus any cloud projects you backed up yourself). You can delete your account yourself at any time: tap "Delete account" at the bottom of Me → Account, and the account number, email, password, Google account ID, device list, sign-in sessions, licence records and cloud files are erased immediately, with no need to contact us (see section 4). If you cannot get into the App, you can ask us by email instead — see the Delete your account page. Deleting your account does not cancel a Google Play subscription, so cancel it in Google Play first. Database backups are kept for at most 30 days, so deleted data is gone from them within 30 days at the latest. You can also delete just part of an account: unlink a device on the same page, or simply sign out. The trial record is not tied to an account; to have it deleted, email us the device code — after that, the device can start a trial again.

10. Changes to This Policy

If we update this policy, we will revise this page and update the "Effective date" above. Material changes will be noted in the App or store listing.

11. Contact Us

For any questions about this Privacy Policy, contact: luoyb0812@gmail.com