A C# library for synchronizing data between databases using delta encoding.

Target Framework: .NET 10.0

SyncFramework uses delta-based synchronization to efficiently sync data between databases.

graph TB
    subgraph "Client"
        A[Client Application] --> B[DbContext]
        B --> C[Custom BatchExecutor]
        C -->|Intercept SQL| D[Delta Generator]
        D -->|Store Deltas| E[Delta Store]
        E -->|Push Deltas| F[HTTP Client]
    end
    subgraph "Server"
        F -->|HTTP| G[SyncServer]
        G -->|Store Deltas| H[Server Delta Store]
        H -->|Provide Deltas| G
    end
    subgraph "Other Clients"
        G -->|HTTP| I[Other Clients]
        I -->|Push Deltas| G
    end
    style A fill:#d4f1f9,stroke:#333
    style G fill:#ffcccc,stroke:#333

SyncFramework replaces EF Core's internal BatchExecutor with a custom one that intercepts generated SQL commands (deltas), stores them, and makes them available for replay on remote databases — even across different database engines.

Package	Description	Link
BIT.Data.Sync	Core interfaces and base classes
BIT.Data.Sync.EfCore	EF Core implementation
BIT.Data.Sync.EfCore.Npgsql	PostgreSQL support
BIT.Data.Sync.EfCore.MySql	MySQL support (official Oracle driver)
BIT.Data.Sync.EfCore.Sqlite	SQLite support
BIT.Data.Sync.EfCore.SqlServer	SQL Server support

dotnet add package BIT.Data.Sync.EfCore.SqlServer   # SQL Server
dotnet add package BIT.Data.Sync.EfCore.Sqlite       # SQLite
dotnet add package BIT.Data.Sync.EfCore.Npgsql       # PostgreSQL
dotnet add package BIT.Data.Sync.EfCore.MySql        # MySQL (Oracle)

var services = new ServiceCollection();
var httpClient = new HttpClient { BaseAddress = new Uri("https://your-sync-server/") };

services.AddSyncFrameworkForSQLite(
    connectionString: "Data Source=deltas.db;",
    httpClient: httpClient,
    serverNodeId: "MemoryDeltaStore1",
    identity: "my-client-id",
    new SqliteDeltaGenerator(),
    new SqlServerDeltaGenerator()
);

var serviceProvider = services.BuildServiceProvider();

var options = new DbContextOptionsBuilder().UseSqlite("Data Source=myapp.db;").Options;
var ctx = new MyDbContext(options, serviceProvider);
await ctx.Database.EnsureCreatedAsync();

await ctx.PushAsync();   // send local deltas to server
await ctx.PullAsync();   // fetch + apply server deltas locally
await ctx.FetchAsync();  // fetch deltas without applying

// Program.cs / Startup.cs
services.AddSyncServerWithMemoryNode("MemoryDeltaStore1");

// SyncController.cs
[ApiController]
[Route("sync")]
public class SyncController : SyncControllerBase
{
    public SyncController(ILogger<SyncControllerBase> logger, ISyncFrameworkServer server)
        : base(logger, server) { }
}

src/Tools/SyncFramework.Dashboard is a Blazor Server admin UI for managing sync server nodes.

cd src/Tools/SyncFramework.Dashboard
ASPNETCORE_ENVIRONMENT=Development dotnet run
# Open http://localhost:5000

Nodes — overview of all active sync nodes

Add Node — spin up a new node with store type selection

Replay — apply a node's deltas into a local SQLite file

1. Data Synchronization in a Few Words
2. Parts of a Synchronization Framework
3. Let's Write a Synchronization Framework in C#
4. Synchronization Framework Base Classes
5. Planning the First Implementation
6. Testing the First Implementation (Video)
7. Adding Network Support

• Database Testing Documentation
• API Reference
• Playground

All notable changes are documented in CHANGELOG.md, following the Keep a Changelog format.

When opening a PR or making a commit that changes behavior:

1. Add an entry under the [Unreleased] section at the top of CHANGELOG.md
2. Use the appropriate category:
   • Added — new features
   • Changed — changes to existing behavior
   • Deprecated — soon-to-be removed features
   • Removed — removed features
   • Fixed — bug fixes
   • Security — vulnerability fixes
   • Breaking Changes — changes that break backward compatibility
3. On release, rename [Unreleased] to the version number and date, e.g. [10.1.0] — 2026-05-01

Example entry:

## [Unreleased]

### Added
- `IDeltaStore.PurgeAsync` — bulk delete deltas older than a given date

### Fixed
- Replay page now handles empty delta stores without crashing

dotnet new install BIT.Data.Sync.Templates
dotnet new SyncServer -o MySyncServer