Swr.Net

A .NET library that brings the stale-while-revalidate (SWR) caching strategy to Blazor and ASP.NET Core. Serve cached data instantly while revalidating in the background — the user always sees data fast, and it's always eventually fresh.

How it works

1. Stale — Return cached data instantly. The UI is never blocked.
2. Revalidate — Fetch fresh data in the background.
3. Update — Swap in new data. Every subscriber re-renders automatically.

Installation

dotnet add package Swr.Net --prerelease

Quick start — Blazor

Register the services in Program.cs:

builder.Services.AddSwrForBlazor();

Use ISwr in any Blazor component:

@using Swr.Net
@inject ISwr Swr
@implements IDisposable

@if (result is not null)
{
    @if (result.IsLoading)
    {
        <p>Loading...</p>
    }
    @if (result.Data is not null)
    {
        <h2>@result.Data.Name</h2>
    }
}

@code {
    private SwrResult<User>? result;

    protected override async Task OnInitializedAsync()
    {
        result = await Swr.GetAsync<User>("/api/users/me");
    }

    public void Dispose() => result?.Dispose();
}

Quick start — ASP.NET Core

Register the services in Program.cs:

builder.Services.AddSwrForAspNetCore();

Features

• Stale-While-Revalidate — Instant UI with cached data, fresh data in the background
• Request Deduplication — Concurrent requests for the same key share one network call
• Automatic Retry — Exponential backoff on failure with configurable attempts
• Cache Mutations — Invalidate by key, prefix, or clear all
• Reactive Results — INotifyPropertyChanged + OnRevalidated event for UI binding
• Platform-Aware DI — Scoped for Blazor (per-circuit), Singleton for ASP.NET Core
• Pluggable Storage — ISwrStore interface for custom cache backends

Documentation

https://kidchenko.github.io/swr-dotnet

License

MIT