For C# developers and everyone learning to code

Write C#. Press F5. See the answer.

QPad is a scratchpad for C#. Try out an idea, query your database with LINQ or explore data – without creating a single project.

Download for Windows How to use QPad

No solution, csproj or Main
LINQ against SQL Server, PostgreSQL and SQLite
NuGet packages in one click

QPad

SquaresCustomers

Enumerable.Range(1, 5)
    .Select(n => new { n, Square = n * n })
    .Dump("Squares");

ResultsSQL

Squares

#	n	Square
0	1	1
1	2	4
2	3	9
3	4	16
4	5	25

Completed in 0.31 s

Features

Everything you need to think in code

One tool that does one thing well: gets you answers fast.

Run code instantly

Write an expression, a few statements or a whole program, and press F5. No solution, project file or Main method.

See everything with .Dump()

Lists, objects, dictionaries and nested structures become tidy tables. Stop guessing with Console.WriteLine.

LINQ against SQL Server, PostgreSQL and SQLite

Connect to your database and your tables are available in code. The schema tree shows tables, columns and relationships, and you drag them straight into the editor.

See the SQL that actually runs

The SQL tab shows what your LINQ query turned into. Handy when you want to understand, debug or fine-tune a query.

NuGet in one click

Search nuget.org and your own package sources, including private Azure DevOps feeds, and add packages with all their dependencies. Your own DLLs work too.

An editor that helps you

Code completion, parameter info and errors as you type, from Roslyn – the compiler behind C#. Ctrl+K, Ctrl+D formats the code, as in Visual Studio.

Safe and isolated

Every script runs in its own process. An infinite loop? Press Stop and carry on as before.

Tabs, files and folders

Work on several queries at once. Save them as .qpad files in folders under My qPads, and get your tabs back just as you left them.

Light or dark

The interface follows the Windows theme, or you pick light or dark yourself. The syntax colors are tuned for both.

QPad is a Windows app built on .NET 10, with support for SQL Server, PostgreSQL and SQLite. Scripts are written in C# and compiled with Roslyn.

How it works

From idea to answer in three steps

1
Write

Open QPad and write C#. Choose Expression for a single expression, Statements for a series of statements or Program for a whole file.
2
Run

Press F5. The code compiles in a blink and runs in a separate process, so your editor never hangs.
3
Explore

Results are shown as tables, and the SQL tab shows the queries that ran. Tweak the code and run it again – each round takes seconds.

Use cases

Everything you would otherwise create a console project for

Whenever you think “I just need to try this quickly”, open QPad.

Try new libraries and APIs

Get the package from NuGet, call its methods and see what they actually return – before you decide to use it.

Explore and analyze data

Ask your database questions with LINQ: group, filter and compare. The answers come back as tables you can read right away.

Try out logic and algorithms

Sketch business rules, calculations or an algorithm, and see that it works before it lands in the big code base.

Test regular expressions, dates and formatting

Find out “how does this actually behave?” in seconds, instead of digging through documentation or guessing.

One-off scripts and automation

Tidy up files, convert data or run a one-off job against the database without setting up a whole project.

Document and share

Save a query as a .qpad file and share it with colleagues, or keep it in the repository as living documentation.

For developers

Less setup. More insight.

Every time you open an IDE, create a project and wait for the build just to answer one small question, you lose your flow. QPad removes everything between the question and the answer.

You get faster answers, a better understanding of your data and a safe place to experiment – without test code ending up in your real projects.

Fast feedback

From idea to answer in seconds. No projects to create and nothing to set up – just code and results.
Understand your data, don't just look at it

.Dump() makes objects, lists and nested structures readable. It beats digging in the debugger or printing line by line.
LINQ and SQL in one place

Write LINQ and see the SQL that actually runs. You catch inefficient queries before they reach production.
Experiment without risk

Scripts run isolated from the editor and can be stopped with one click. Try whatever you like – you can always cancel.
The whole .NET ecosystem

Use NuGet packages and your own DLLs straight from the script. The same language and libraries as the rest of your code.
Reuse what works

Save useful queries and scripts as files, and share them with your team as documentation or tools.

For those learning to code

The fastest way to understand C#

Learning to program is about trying, seeing what happens and trying again. QPad makes that loop as short and clear as possible.

Nothing to set up

No project templates, no folders and no configuration to learn first. Open the app and write your first line of C#.

See what your code does

Every value, list and object becomes a table. It becomes concrete what a dictionary, a list or a LINQ expression really is.

Error messages you can click

Make a mistake and it is underlined as you type. When you press F5, you get a message with line and column – click it to jump straight to the spot in your code.

Learn LINQ and SQL together

Write a LINQ query and see the SQL it becomes. That way you learn both – and see how they fit together.

Experiment without fear

You can't break anything by trying. Change, run, undo – and learn from what happens.

Learn from complete examples

Every example is complete and runs as it is. Paste it in, press F5 and start changing things.

Teaching C#?

Students don't have to set up an IDE before the first class. Share exercises as small files, let them run the examples themselves, and use the dark or light theme depending on what works best in the room.

Try it yourself

Four small examples to start with

Paste them into QPad, press F5 and start changing things.

Understand LINQ

Group words by their first letter and see the result as a table.

var words = new[] { "apple", "banana", "apricot", "avocado", "blueberry" };

words.GroupBy(w => w[0])
     .Select(g => new { Letter = g.Key, Count = g.Count() })
     .Dump();

Regular expressions in seconds

Find every phone number in a text, without digging through the documentation.

using System.Text.RegularExpressions;

var text = "Call 555-0142 or 555-0199";

Regex.Matches(text, @"\d{3}-\d{4}")
     .Select(m => m.Value)
     .Dump("Phone numbers");

JSON with a NuGet package

Add Newtonsoft.Json under “References…” and use it right away.

using Newtonsoft.Json;

var json = JsonConvert.SerializeObject(
    new { Name = "Kari", Age = 29 });
json.Dump();

JsonConvert
    .DeserializeObject<Dictionary<string, object>>(json)
    .Dump();

Query your database with LINQ

Connect to a database and drag a table into the editor. “Customers” is an example – use your own tables.

Customers
    .Where(c => c.Name.StartsWith("A"))
    .OrderBy(c => c.Name)
    .Take(10)
    .Dump();

// The SQL tab shows the query that ran

Get started

Ready to write your first line?

Download QPad, install it just for you without administrator rights, and press F5 on the example that is ready and waiting.

Windows 10 or 11 (64-bit) .NET 10 Desktop Runtime SQL Server, PostgreSQL or SQLite (optional)

Download QPad Read the help