API & Load Tester for VS Code
A full-featured API testing and load testing extension for Visual Studio Code. Test APIs, stress test endpoints, and explore OpenAPI specs — all without leaving your editor.
Features
🔌 API Tester
- Full HTTP request builder (GET, POST, PUT, PATCH, DELETE, HEAD, OPTIONS)
- Key-value editors for headers and query parameters
- URL ↔ Query Params bi-directional sync
- Request body editor with JSON support
- Response viewer with status, timing, headers, and pretty-printed body
- Copy response to clipboard
📁 Collections
- Organize requests into named collections
- Save, load, rename, and delete requests
- Persists across VS Code sessions
🕒 Request History
- Auto-saves recent requests with status and timing
- Quick replay any previous request
- Configurable history size
⚡ Load Tester
- Concurrent user simulation with configurable count
- Adjustable test duration and ramp-up time
- Custom headers and request body support
- 10 live metric cards updating every second:
- Requests/sec, Total Requests, Avg/Min/Max/P95/P99 Latency, Error Rate, Total Errors, Active Users
- 4 real-time charts:
- Latency Over Time (Line)
- Throughput (Bar)
- Error Rate (Area)
- Response Time Distribution (Histogram)
- Export results as JSON or CSV
📋 OpenAPI Integration
- Import from URL or paste raw JSON/YAML
- Supports OpenAPI 2.0 (Swagger), 3.0.x, and 3.1.x
- Browse endpoints grouped by tags with color-coded method badges
- View parameters, request bodies, and responses
- Click to load any endpoint directly into the API Tester
- Save entire spec or individual tags as collections
- Auto-generated sample request bodies from JSON Schema
Requirements
- Java 21+ (JDK) must be installed and available on your PATH
- The extension includes an embedded backend server that starts automatically
Usage
Sending a Request
- Select HTTP method from the dropdown
- Enter the URL
- Add headers/params as needed
- Click Send or press Ctrl+Enter
Running a Load Test
- Switch to the Load Tester tab
- Enter the target URL and configure users/duration
- Click Start Load Test
- Watch live metrics and charts update in real-time
- Export results as JSON or CSV after completion
Exploring an OpenAPI Spec
- Switch to the OpenAPI tab
- Paste a spec URL or raw content
- Browse endpoints, view details
- Click ▶ Test to load into the API Tester
Extension Settings
| Setting |
Default |
Description |
apiLoadTester.backendPort |
8081 |
Port for the backend server |
apiLoadTester.requestTimeout |
30000 |
Request timeout in milliseconds |
apiLoadTester.maxHistorySize |
50 |
Maximum requests to keep in history |
Keyboard Shortcuts
| Shortcut |
Action |
Ctrl+Enter |
Send current request |
Known Issues
- The embedded backend requires Java 21+ to be installed
- On Windows, the backend process may occasionally persist after VS Code closes. It will be automatically cleaned up on next launch.
Tech Stack
- Extension: TypeScript, VS Code Extension API
- UI: React, Vite, Recharts
- Backend: Spring Boot 4.0 (WebFlux/Netty), Java 21
- Live Metrics: Reactive WebSocket
- OpenAPI: swagger-parser 2.1.22
License
MIT
| |
