Nifty C# Scratchpad

Run C# snippets instantly with NuGet packages and rich Dump() output: a LINQPad-style scratchpad and Polyglot Notebooks replacement.

Maintained. No sign-in. No telemetry. Works in VS Code, Cursor, Windsurf, VSCodium and other editors that use Open VSX.

Why

Polyglot Notebooks and .NET Interactive were discontinued in 2026, and LINQPad is a separate app. Nifty C# Scratchpad gives you a quick place to try C# code, explore data and test a NuGet package, right inside your editor. It's built on .NET 10's official dotnet run file.cs, so it uses the real compiler and runtime.

Features

LINQ over some orders pasted into a scratchpad and run with Ctrl+Enter, its Dump() results appearing as tables beside it

A scratchpad with LINQ over some orders, and its Dump() results as tables beside it

A compile error shown in the output and in Problems, on the scratchpad's own line

Scratchpads in one keystroke. Ctrl+Alt+Shift+N creates a new scratchpad. Your scratchpads are kept for next time (Open Scratchpad…).
Run with Ctrl+Enter in a scratchpad (Ctrl+Alt+Enter in any C# file), the ▶ button, or the Run CodeLens at the top. Runs take about a second once built.
Dump() anything.
```
var orders = db.Orders.Where(o => o.Total > 100).Take(20).ToList();
orders.Dump("Big orders");
```
Lists of objects become tables, nested objects become expandable tables, and numbers, strings, booleans and nulls are colour-coded. Dump() returns its value, so you can chain it. Large sequences are cut off at 1,000 items (Dump(maxItems: 50) to change).
NuGet packages in one step. Add NuGet Package… searches nuget.org and adds a line like #:package Dapper@2.1.35; it's restored automatically on the next run.
Compile errors where you need them. In the output panel (click to jump to the line) and in the Problems panel.
Any .NET 10 file-based app. Also runs .cs files in your projects that use top-level statements or #:package / #:sdk directives.
Export output as an HTML report, JSON, or CSV (one Dump() at a time).
Run on save: scratchpads re-run every time you save.
Snippet library: save and insert reusable code across scratchpads.
Stop long-running code at any time.
Private. .NET CLI telemetry is switched off for every run the extension starts.

Requirements

The .NET 10 SDK or newer. Nifty C# Scratchpad finds it on your PATH or in the standard install locations, or set nifty.csharp-scratchpad.dotnetPath.

For IntelliSense in scratchpads, use the C# extension (or C# Dev Kit) as usual.

Commands

Command	Key	What it does
`Run Scratchpad`	`Ctrl+Enter` in scratchpads, `Ctrl+Alt+Enter` in C# files	Build and run
`Stop`		Stop the running code
`New Scratchpad`	`Ctrl+Alt+Shift+N`	Create a scratchpad
`Open Scratchpad…`		Pick an existing scratchpad
`Add NuGet Package…`		Search nuget.org and add a `#:package` line
`Reveal Scratchpad Folder`		Show where scratchpads are stored
`Export Output…`		HTML, JSON or CSV
`Toggle Run on Save`		Re-run when you save
`Save to / Insert from Snippet Library`		Reusable snippets

Settings

Setting	Default	What it does
`nifty.csharp-scratchpad.dotnetPath`	(empty)	Path to `dotnet`; empty means find it automatically
`nifty.csharp-scratchpad.runArguments`	`[]`	Extra `dotnet run` arguments, e.g. `["-c", "Release"]`
`nifty.csharp-scratchpad.codeLens`	`true`	Show Run / Add NuGet Package above runnable files

Install

VS Code: search for "Nifty C# Scratchpad" in the Extensions view, or install from the Visual Studio Marketplace.
Cursor, Windsurf, VSCodium, Kiro, Antigravity: install from Open VSX.

Privacy

This extension collects no telemetry and needs no account. It contacts nuget.org only when you search for a package.

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Nifty C# Scratchpad: Run C# Snippets & NuGet

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