Monica for Windows

Monica by Avalonia: a local-first cross-platform password vault built with Avalonia, .NET, and MDBX.
Windows / macOS / Linux · Local Vault · MDBX-1 · KeePass · TOTP · WebDAV / OneDrive

Monica by Avalonia

Avalonia + .NET + MDBX local password vault

Project contributor

Project contributor

Abstract

Monica for Windows is the desktop implementation of the Monica password vault, focused on local-first password management and MDBX vault compatibility. This document follows a README-style structure and provides a feature overview, tech stack, architecture view, and development notes.

Monica for Windows aims to carry Monica’s local-first and security-first direction onto desktop platforms, offering management for passwords, TOTP, private notes, bank cards, and identity documents, along with local encryption, import/export, backup, and MDBX vault compatibility.

Project Positioning

Monica for Windows is a local-first password vault client for desktop users. Built on Avalonia’s cross-platform desktop UI together with .NET 10 and the MDBX local vault, it is designed to deliver a desktop password management experience that is both modern and extensible.

Core goals of the project:

Provide local encrypted vault and TOTP management capabilities
Support compatibility with KeePass .kdbx and Monica / MDBX data
Support backup and restore through WebDAV and OneDrive
Provide desktop integrations such as file pickers, clipboard access, system tray support, and global shortcuts

What You Get

Local password vault: manage accounts, passwords, URLs, custom fields, attachments, and categories
TOTP management: store and generate dynamic verification codes
Private notes: support plain text and Markdown preview
Cards and identity documents: manage bank cards, identity data, and other sensitive information in one place
Password generation: built-in random password generation and strength analysis
Local encryption: master password initialization, unlock, change, and secure recovery settings
Import and export: support Monica JSON, password CSV, TOTP CSV, Aegis JSON, and more
Sync and backup: WebDAV / OneDrive backup and restore
MDBX vault: create, inspect, and manage Monica MDBX-1 local databases

Tech Stack

Layer	Technology	Notes
Desktop UI	Avalonia 12, FluentAvaloniaUI, FluentIcons.Avalonia	Cross-platform desktop UI and Fluent-style controls
Application framework	.NET 10, C# nullable, compiled bindings	Modern .NET desktop runtime and type-safe bindings
MVVM	CommunityToolkit.Mvvm	ViewModels, commands, and property notifications
Dependency injection and logging	Microsoft.Extensions.DependencyInjection, Microsoft.Extensions.Logging, Serilog	Service registration and logging abstractions
Local data	Microsoft.Data.Sqlite, SQLitePCLRaw, Dapper, Dapper.AOT	Lightweight data access, migrations, and AOT-friendly queries
Cryptography and security	BouncyCastle, Argon2, ProtectedData, AES/SHA-related implementations	Master password derivation and local data protection
Password capabilities	PasswordGenerator, zxcvbn-core, Pwned Password checks	Password generation, strength evaluation, and risk detection
TOTP / QR	Otp.NET, QRCoder, ZXing.Net	Dynamic codes and QR-code generation/parsing
Import/export	CsvHelper, SharpCompress, System.Text.Json	CSV, JSON, compressed backup, and migration
KeePass ecosystem	KPCLib	`.kdbx` compatibility
Cloud and sync	WebDav.Client, Microsoft.Graph, Azure.Identity, MSAL, Polly	WebDAV, OneDrive, authentication, and retry policies
MDBX integration	Rust MDBX workspace, UniFFI, `mdbx_ffi.dll`	Reuses Monica MDBX vault core capabilities
Testing	xUnit, Microsoft.NET.Test.Sdk, coverlet	Tests for core services and platform services

Architecture Overview

Architecture Preview

The architecture of Monica for Windows can be understood as a “desktop password vault thought tree,” centered on:

The UI layer for interaction and presentation
The Core layer for business logic and cryptography
The Data layer for vault storage and persistence
The Platform layer for sync, platform integration, and MDBX adaptation

Architecture Notes

Monica.App: Avalonia UI, windows, and desktop services
Monica.Core: domain models, cryptography, TOTP, import/export, password generation
Monica.Data: local database, vault storage, migrations, and MDBX backend repositories
Monica.Platform: cross-platform adaptation layer including WebDAV, OneDrive, KeePass, and the MDBX bridge
MDBX Rust workspace: vault core, cryptography, storage, FFI, and CLI support
OS integrations: file pickers, clipboard, DPAPI, browser bridge
Remote backup: WebDAV/OneDrive backup and restore channels

WARNING

In this architecture, MDBX is not an ordinary database table. Commit, snapshot, and conflict metadata must be managed through dedicated APIs or an FFI facade.

mermaid

mindmap
  root((Monica for Windows))
    App["Monica.App\nAvalonia UI / ViewModels / Dialog Services"]
      UI[UI / Interaction]
      Dialogs[Dialogs / Desktop Services]
    Core["Monica.Core\nDomain Models / Crypto Services / TOTP / Import & Export"]
      Security[Crypto / Master Password]
      TOTP[TOTP / Generation]
      ImportExport[Import & Export]
      PasswordGen[Password Generation]
    Data["Monica.Data\nSQLite / Vault / MDBX Backend"]
      Storage[SQLite / Vault]
      Migration[Migrations]
      MDBXStore[MDBX Backend]
    Platform["Monica.Platform\nWebDAV / OneDrive / KeePass / MDBX bridge"]
      Sync[WebDAV / OneDrive]
      KeePass[.kdbx / KeePass]
      MDBXBridge[MDBX bridge]
    Os["OS integrations\nDPAPI / Clipboard / File Picker / Browser Bridge"]
      Clipboard[Clipboard]
      FilePicker[File Picker]
      DPAPI[DPAPI]
      BrowserBridge[Browser Bridge]
    Cloud["Backup and Restore\nWebDAV / OneDrive"]
      Backup[Backup]
      Restore[Restore]

Code Directories

monica by avalonia/src/Monica.App: Avalonia app entry point, main window, ViewModels, and desktop UI services
monica by avalonia/src/Monica.Core: core models, cryptography, TOTP, password generation, import/export, and security capabilities
monica by avalonia/src/Monica.Data: SQLite database, Dapper repositories, migrations, vault storage, and MDBX backend repositories
monica by avalonia/src/Monica.Platform: platform adapters, WebDAV, OneDrive, KeePass, Windows Secret Protector, and MDBX UniFFI native bridge
monica by avalonia/tests/Monica.Tests: tests for core services, repositories, MDBX integration, and platform services

MDBX-1 Integration

Monica for Windows supports the MDBX-1 local-first vault. It is not an ordinary SQLite password table, but a local database format with version history, conflict handling, snapshot recovery, and security boundaries.

The Avalonia side currently includes two MDBX integration paths:

MdbxUniffiNativeBridge: calls the UniFFI bridge through mdbx_ffi.dll to operate the MDBX vault directly inside the local process
MdbxCliVaultEngine: falls back to the MDBX CLI when the native bridge is unavailable, mainly for development and validation

MDBX clients must maintain commit, tombstone, snapshot, conflict, and device-head metadata through the storage / repo APIs provided by the library or through an explicit FFI facade. Do not modify the underlying files directly.

For more details, refer to the MDBX repository documentation.

Quick Start

Requirements

.NET SDK 10.0+
Windows desktop environment
Rust toolchain if you want MDBX CLI fallback support

Restore and Build

powershell

cd "e:\projects\MonicaDocs\docs\03.生态\03.Windows\monica by avalonia"
dotnet restore Monica.slnx
dotnet build Monica.slnx

Run the Desktop App

powershell

dotnet run --project "src\Monica.App\Monica.App.csproj"

Run Tests

powershell

dotnet test Monica.slnx

Publish Example

powershell

dotnet publish "src\Monica.App\Monica.App.csproj" -c Release -r win-x64 --self-contained true

Current Status

The project is in an early development stage (0.1.0) and mainly serves as the desktop architecture and MDBX integration baseline.
Test foundations already cover app settings, core services, password management, TOTP, MDBX storage, and platform services.
For real sensitive data, multiple backups are still strongly recommended. More screenshots and release notes are still needed before a formal release.

Relationship to Monica / MDBX

Monica: provides the product vision, local-first direction, and password management UX reference
MDBX: provides the local-first vault format and long-term maintainable data structures
Monica for Windows: merges both into a desktop implementation for Windows

Acknowledgements

Monica for Windows references and draws inspiration from the following projects:

Avalonia: cross-platform desktop UI
FluentAvalonia: Fluent-style controls
Bitwarden: password management ecosystem reference
KeePass: local vault and .kdbx compatibility reference
MDBX: local-first vault format reference

License

This project is open-sourced under the GNU General Public License v3.0.

Monica for Windows ​

Project Positioning ​

What You Get ​

Tech Stack ​

Architecture Overview ​

Code Directories ​

MDBX-1 Integration ​

Quick Start ​

Requirements ​

Restore and Build ​

Run the Desktop App ​

Run Tests ​

Publish Example ​

Current Status ​

Relationship to Monica / MDBX ​

Acknowledgements ​

License ​

Monica for Windows

Project Positioning

What You Get

Tech Stack

Architecture Overview

Code Directories

MDBX-1 Integration

Quick Start

Requirements

Restore and Build

Run the Desktop App

Run Tests

Publish Example

Current Status

Relationship to Monica / MDBX

Acknowledgements

License