A VS Code extension for building, running, and debugging Gcore FastEdge applications — with a Postman-like interface for crafting requests and inspecting responses.
Supports both HTTP apps and CDN apps across three languages:
| App Type | Languages | SDK |
|---|---|---|
| HTTP | Rust, JavaScript | FastEdge-sdk-rust, FastEdge-sdk-js |
| CDN | Rust, AssemblyScript | proxy-wasm-sdk-rust, proxy-wasm-sdk-as |
The extension compiles your code into a WASM binary using language-specific build tools, then serves it locally using a bundled debugger — no external tools required.
A webview panel opens inside VS Code where you can:
- Build requests (URL, method, headers, body)
- Send them to your running app
- Inspect the response (status, headers, body)
- Load and save test configurations
Each app gets its own isolated server instance on a port in the range 5179–5188, so you can debug multiple apps in the same workspace simultaneously.
You need the build tools for your chosen language installed:
Rust (HTTP or CDN apps):
rustup target add wasm32-wasip1JavaScript (HTTP apps):
npm install --save-dev @gcoredev/fastedge-sdk-jsAssemblyScript (CDN apps):
npm install --save-dev assemblyscript @assemblyscript/wasi-shim @gcoredev/proxy-wasm-sdk-asMore detail can be found in the SDK documentation linked above.
This extension can be installed from the Visual Studio Marketplace: FastEdge Launcher
It is also possible to install from source: Releases
Press F5 in VS Code (or Command Palette → Debug: Start Debug).
When running for the first time, you'll need a .vscode/launch.json. The easiest way is to let the extension create one:
Command Palette (Ctrl+Shift+P) → FastEdge: Initialize workspace (create launch.json)
{
"version": "0.2.0",
"configurations": [
{
"name": "FastEdge App Runner: Launch",
"type": "fastedge",
"request": "launch",
"entrypoint": "file"
}
]
}The entrypoint field controls how the build finds your source code:
| Value | Behavior |
|---|---|
"file" (default) |
Builds the currently active editor file |
"package" |
Builds from the "main" field in package.json (JavaScript only) |
These are the only configuration values read from launch.json. Runtime arguments (env vars, headers, etc.) are configured separately — see Runtime Configuration below.
The extension auto-detects your project language:
| Indicator | Detected as |
|---|---|
VS Code language ID = rust |
Rust |
asconfig.json exists at project root |
AssemblyScript |
JS/TS file without asconfig.json |
JavaScript |
Available from the Command Palette (Ctrl+Shift+P):
| Command | Description |
|---|---|
| Debug: FastEdge App (Current File) | Build the active file and start the debugger |
| Debug: FastEdge App (Package Entry) | Build from package.json main field and start the debugger |
| FastEdge: Initialize workspace | Create .vscode/launch.json with default configuration |
| FastEdge (Generate mcp.json) | Add the FastEdge MCP Server to your workspace |
| FastEdge (Setup Codespace Secrets) | Configure GitHub Codespaces secrets for FastEdge |
Right-click actions in the file explorer:
| Command | Appears on | Description |
|---|---|---|
| FastEdge: Load in Debugger | .wasm files |
Load a pre-compiled WASM binary directly into the debugger |
| FastEdge: Load Config in Debugger | *test.json files |
Load a test configuration file into the debugger |
Environment variables, secrets, request headers, and response headers are configured through test configuration files — not launch.json.
The debugger UI provides built-in controls to set environment variables, secrets, and headers. These are saved to and loaded from fastedge-config.test.json in your app root, using native file dialogs.
You can also provide runtime arguments via .env files that the extension auto-discovers from your app root directory.
Please be aware that if you are adding sensitive information to these files, they should be added to your .gitignore:
# VSCode workspace
.vscode/
# dotenv files
.env
.env.*
# Build artifacts
.fastedge-debug/
For more information on how the extension locates and uses dotenv files, see DOTENV.md.
| Setting | Description |
|---|---|
fastedge.cliVersion |
The version of the bundled debugger (read-only) |
fastedge.apiUrl |
Default FastEdge API URL for MCP server configuration |
To view the bundled debugger version:
- Open Settings (Ctrl+, or Cmd+,)
- Search for "FastEdge"

