LocalChat is a Flutter LAN direct-transfer tool for sending text, links, images, and files between Windows and Android devices through a chat-style interface.
LocalChat 是一个 Flutter 局域网直连传输工具，用聊天窗口的方式在 Windows 和 Android 设备之间发送文字、链接、图片和文件。
- GitHub Releases：https://github.com/Mintcolour/LocalChat/releases
LocalChat 不是云盘，也不是公网 IM。它面向更常见的本地场景：电脑和手机处在同一网络环境时，可以快速、私密、可追踪地互传内容，不需要登录账号，也不依赖第三方中转服务器。
- 局域网直连：设备通过 UDP 广播发现彼此，传输走本地 HTTP 服务。
- 聊天式体验：文字、链接、图片和文件都落在同一条会话时间线里，方便回看发送记录、传输状态和保存位置。
- 首次可信配对：通过 6 位校验码建立信任关系，后续可信设备可直接通信。
- 应用层安全：请求签名使用 Ed25519，密钥协商使用 X25519，文字与文件分块使用 AES-GCM 加密。
- 跨端统一实现：Windows 和 Android 共享主要业务逻辑，便于继续扩展平台能力。
已实现：
- 文件夹递归传输并保留目录结构，单文件和文件夹传输可共享会话历史。
- 手动填写 IP 和端口添加设备，支持跨网段直连场景。
- Windows 托盘、开机自启、单实例唤醒。
- 独立传输中心，集中查看进行中、已完成、失败或已取消的文件传输。
- 出站传输排队、整组进度展示和取消兼容能力。
- 发送前附件预览、排序、移除，支持多文件整理后统一发送。
- 图片发送前裁切、旋转、文字标注，编辑过程仅在本地完成。
- 接收文件支持重命名，并按会话、年月和文件类型分类归档。
- 传输历史支持打开文件、打开文件夹，以及对已保存接收文件重命名。
- 浅色、深色、跟随系统主题三种外观模式。
- 失败消息重试、聊天记录分页加载、日期分隔、未读数和消息搜索定位。
- 设备在线/离线状态使用独立图标显示，不会被最近消息预览覆盖。
- 设置页显示本机局域网 IP 和监听端口，便于手动连接。
- 移动端会话切换动画，以及返回键退出会话问题修复。
- Windows 拖拽发送、剪贴板文件或图片发送、Android 系统分享入口。
- Drift/SQLite 本地历史保存设备、会话、消息、传输和设置数据。
当前限制：
- 自动发现主要面向同一局域网；跨网段设备需要手动填写 IP 和端口。
- MVP 仍以本地前台收发为主，后台常驻和更完整的断点续传仍在规划中。
- 按 Flutter 官方文档安装 Flutter SDK：https://docs.flutter.dev/get-started/install
- 如需构建 Android，请按官方文档安装 Android toolchain：https://docs.flutter.dev/get-started/install/windows/mobile
- 如需构建 Windows，请按官方文档启用 Windows desktop：https://docs.flutter.dev/platform-integration/windows/setup
- 安装完成后执行
flutter doctor，确认依赖齐全。
仓库提供了 scripts/flutter_env.ps1 作为 PowerShell 环境辅助脚本。使用前请按本机实际工具链自行调整，不要把本地路径或私有环境信息写回文档或提交到仓库。
安装依赖：
flutter pub get运行检查和测试：
flutter analyze
flutter test构建 Android Release APK：
flutter build apk --release --split-per-abiAPK 输出目录：
build\app\outputs\flutter-apk
构建 Windows Release：
flutter build windows --releaseWindows 输出目录：
build\windows\x64\runner\Release
- 在两台设备上打开 LocalChat。
- 在设备列表中找到对方设备，或手动输入对方的 IP 和端口。
- 首次连接时确认 6 位校验码，建立信任关系。
- 在会话中发送文字、链接、图片、文件或文件夹。
- Windows 可拖拽文件到聊天区，也可以粘贴剪贴板中的文件或图片；Android 可通过系统分享菜单发送到 LocalChat。
- 手机和电脑之间临时传截图、安装包、文档、链接。
- 不希望文件经过公网服务器的办公室或家庭局域网传输。
- 需要保留传输上下文和历史记录，而不只是一次性投递文件。
- 想研究 Flutter 跨端、局域网发现、安全传输和本地持久化组合实现的示例项目。
- 更完整的断点续传和传输恢复能力。
- 更稳定的后台常驻、移动端保活和网络切换体验。
- 更多平台支持，以及更细的权限与设备管理能力。
- GitHub Releases: https://github.com/Mintcolour/LocalChat/releases
LocalChat is not a cloud drive or a public instant messenger. It is built for the more common local workflow: when your phone and computer are on the same network, you can quickly and privately exchange content without signing in, and without routing data through a third-party relay service.
- LAN direct transfer: devices discover each other with UDP broadcast and transfer data through a local HTTP service.
- Chat-style workflow: text, links, images, and files stay in one conversation timeline so status, sender, time, and saved location remain visible.
- Trusted first pairing: devices establish trust with a 6-digit verification code, then trusted peers can communicate directly.
- Application-level security: requests are signed with Ed25519, peers derive shared keys with X25519, and text plus file chunks are encrypted with AES-GCM.
- Shared cross-platform core: Windows and Android use the same main application logic, making future platform expansion easier.
Implemented:
- Recursive folder transfer with preserved directory structure, integrated into the same conversation history as regular files.
- Manual device add via IP and port for cross-subnet connections.
- Windows tray integration, startup launch, and single-instance activation.
- A dedicated transfer center for active, completed, failed, and canceled file transfers.
- Outbound transfer queueing, grouped progress, and cancel compatibility.
- Attachment preview, sorting, and removal before send.
- Local image crop, rotate, and text annotation before sending.
- Received-file rename support plus archiving by conversation, year/month, and file type.
- Transfer-history actions for opening files, opening folders, and renaming saved received files.
- Light, dark, and follow-system theme modes.
- Failed message retry, paginated chat history, date separators, unread counts, and message search positioning.
- Persistent online/offline device-status icons that stay visible alongside message previews.
- Local LAN IP and listening port display in settings for easier manual connection.
- Mobile conversation transition animations and a fix for the back-navigation exit issue.
- Windows drag-and-drop, clipboard file/image sending, and Android system share entry points.
- Drift/SQLite persistence for devices, conversations, messages, transfers, and settings.
Known limits:
- Automatic discovery is mainly designed for the same LAN; cross-subnet peers still require a manually entered IP and port.
- The current MVP is still centered on foreground transfers. Better background persistence and resumable transfer support are still on the roadmap.
- Install Flutter by following the official guide: https://docs.flutter.dev/get-started/install
- For Android builds, set up the Android toolchain with the official Windows guide: https://docs.flutter.dev/get-started/install/windows/mobile
- For Windows builds, enable Windows desktop support with the official guide: https://docs.flutter.dev/platform-integration/windows/setup
- Run
flutter doctorafter setup and fix any reported dependency issues.
The repository includes scripts/flutter_env.ps1 as a PowerShell environment helper. Adjust it for your own local toolchain before using it, and do not commit local paths or private environment details back into the repository documentation.
Install dependencies:
flutter pub getRun analysis and tests:
flutter analyze
flutter testBuild Android release APKs:
flutter build apk --release --split-per-abiAPK output directory:
build\app\outputs\flutter-apk
Build a Windows release:
flutter build windows --releaseWindows output directory:
build\windows\x64\runner\Release
- Open LocalChat on two devices.
- Find the peer device in the device list, or add it manually by IP and port.
- Confirm the 6-digit verification code on first connection.
- Send text, links, images, files, or folders from the conversation.
- On Windows, drag files into the chat area or paste files and images from the clipboard. On Android, use the system share sheet to send content into LocalChat.
- Quickly move screenshots, APKs, documents, and links between a phone and a computer.
- Transfer files inside a home or office LAN without using a public server.
- Keep transfer context and history instead of relying on one-off send tools.
- Study a practical Flutter example that combines cross-platform UI, LAN discovery, secure transfer, and local persistence.
- More complete resumable transfer and recovery behavior.
- Stronger background persistence, mobile keep-alive behavior, and network-switch handling.
- More platforms and finer-grained permission and device management.