Installation

Napper has two components: the CLI binary and the VS Code extension. The CLI is standalone with no runtime dependencies. The extension shells out to the CLI, so you need both for full VS Code integration.

VS Code Extension

Install from the Marketplace

The easiest way to get Napper in VS Code is from the marketplace:

Option 1 — Marketplace UI:

1. Open VS Code
2. Click the Extensions icon in the Activity Bar (or press Ctrl+Shift+X / Cmd+Shift+X)
3. Search for Napper
4. Click Install on the result published by Nimblesite

Option 2 — Command line:

code --install-extension nimblesite.napper

Option 3 — Quick Open: Press Ctrl+P / Cmd+P and run:

ext install nimblesite.napper

Install a VSIX manually

If you need a specific version or are working in an air-gapped environment, download the .vsix file from GitHub Releases and install it manually.

Via the VS Code UI:

1. Download napper-<version>.vsix from the Releases page
2. Open the Extensions panel (Ctrl+Shift+X / Cmd+Shift+X)
3. Click the ... menu (top-right of the panel)
4. Select Install from VSIX...
5. Browse to the downloaded .vsix file and click Install

Via the command line:

code --install-extension napper-0.10.0.vsix

What the extension provides

Once installed, Napper adds:

• Syntax highlighting for .nap, .naplist, and .napenv files
• Napper panel in the Activity Bar with a request and playlist explorer
• Test Explorer integration — run and inspect results without leaving VS Code
• Environment switcher in the status bar
• CodeLens actions — click Run or Copy as curl above any request
• OpenAPI import — generate test files from any OpenAPI/Swagger spec
• AI enrichment — optional GitHub Copilot integration for smarter assertions

CLI Binary

The CLI is a self-contained binary with no runtime dependencies — no .NET, no Node, no Python required.

Download from GitHub Releases

Download the binary for your platform from GitHub Releases. The current release is v0.10.0.

macOS / Linux — make it executable and move to PATH:

# Example for macOS Apple Silicon
chmod +x napper-osx-arm64
mv napper-osx-arm64 /usr/local/bin/napper

Windows — add to PATH:

Move napper-win-x64.exe to a folder on your PATH, or rename it to napper.exe and add its directory to your system PATH via System Properties → Environment Variables.

Install script (macOS / Linux)

The install script auto-detects your platform and verifies the SHA256 checksum:

curl -fsSL https://raw.githubusercontent.com/MelbourneDeveloper/napper/main/scripts/install.sh | bash

Install a specific version:

curl -fsSL https://raw.githubusercontent.com/MelbourneDeveloper/napper/main/scripts/install.sh | bash -s 0.10.0

Install script (Windows)

irm https://raw.githubusercontent.com/MelbourneDeveloper/napper/main/scripts/install.ps1 | iex

Install a specific version:

.\scripts\install.ps1 -Version 0.10.0

Build from source

If you have the .NET SDK and make installed, you can build from source:

git clone https://github.com/MelbourneDeveloper/napper.git
cd napper
make install-binaries

This builds a self-contained, trimmed, single-file binary for your platform and installs it to ~/.local/bin/napper.

Verify the installation

napper --version
napper --help

You should see the version number and the list of available commands.

Prerequisites

No account is required. Napper is entirely open source and free.

First-time setup

After installing both components:

1. Verify the CLI is on your PATH

Open a terminal and run:

napper --version

If VS Code cannot find the CLI, set the path explicitly in VS Code settings:

{
  "napper.cliPath": "/usr/local/bin/napper"
}

2. Open a folder with .nap files

The Napper panel in the Activity Bar will automatically discover all .nap and .naplist files in your workspace. If you do not have any yet, create a simple one:

GET https://jsonplaceholder.typicode.com/posts/1

Save it as hello.nap.

3. Run your first request

• From VS Code: Click the Run CodeLens link above the request line, or click the play button in the Napper Explorer panel.
• From the CLI: napper run ./hello.nap

4. Set up environments (optional)

Create a .napenv file in your project root with shared variables:

baseUrl = https://api.example.com

Create a .napenv.local file (add to .gitignore) for secrets:

token = your-secret-token
apiKey = your-api-key

Switch environments from the VS Code status bar or with --env on the CLI.

Troubleshooting

VS Code says it cannot find the napper CLI

Make sure the CLI binary is on your system PATH. Test by opening a terminal inside VS Code (Ctrl+`` ) and running napper --version. If it works there but not in the extension, set napper.cliPath explicitly in your VS Code settings.

chmod +x is required on macOS / Linux

After downloading the binary, you must make it executable before running it:

chmod +x napper-osx-arm64

macOS Gatekeeper warning

On macOS, you may see a warning that the binary is from an unidentified developer. Right-click the binary and choose Open, or run:

xattr -dr com.apple.quarantine /usr/local/bin/napper

Script hooks fail with "dotnet not found"

F# (.fsx) and C# (.csx) script hooks require the .NET 10 SDK. Download it from dotnet.microsoft.com. Plain .nap and .naplist files do not need the SDK.

Next steps

• Follow the Quick Start guide to create your first request and test suite
• Learn the .nap file format
• Import an existing API spec with OpenAPI import
• Set up environments for local, staging, and production