API Client
betaThis free API Client lets you import your existing Postman collections, Insomnia workspaces, Swagger/OpenAPI specs or browser HAR archives and execute REST API requests directly in your browser — or with full CORS bypass in the PDFPowerHub desktop app. Environment variables, cross-request token chaining, and per-request response history are all included. Your workspace auto-saves locally and never leaves your device.
Import a collection to get started.
How to use API Client
- 1 Click "Import" and select a Postman JSON, Insomnia JSON, OpenAPI YAML/JSON, or HAR file — the collection populates instantly.
- 2 Click any request in the sidebar to open it. Edit the URL, method, headers, body, or auth as needed.
- 3 Add an environment (the + next to ENV), give it a name, and set variables as KEY=value (one per line). Reference any of them with {{variable_name}} in the URL, params, headers, body or auth — they are substituted when you send.
- 4 Click "Send". The response appears below with status, timing, headers, and formatted body. Open the "Request" tab to see exactly what was sent with variables resolved. Right-click a collection to export back to Postman, Insomnia, or OpenAPI.
Frequently asked questions
How do I check exactly what request was sent?
After sending, open the "Request" tab in the response panel to see the final method, URL, headers (including auth) and body with every {{variable}} resolved — so you can confirm the outgoing request is what you expected. The History tab in the sidebar also lists every request you have sent.
Is my API data uploaded to a server?
No. All request execution, collection parsing, and workspace storage happen locally in your browser or desktop app. Your API keys, tokens, and payloads never leave your device.
Why does it say "Browser mode — CORS restrictions apply"?
Browsers block cross-origin requests to APIs that don't explicitly allow them — this is a browser security policy called CORS. Install the PDFPowerHub desktop app to send requests to any API without CORS restrictions, exactly like Postman or Insomnia.
Which import formats are supported?
Postman Collection v2.1 (JSON), Insomnia Export v4 (JSON), OpenAPI/Swagger 2.0 and 3.x (JSON or YAML), and HAR (HTTP Archive from browser DevTools). Collections are auto-detected — just drop the file.
Can I export my work back to Postman or Insomnia?
Yes. Click the download icon on any collection in the sidebar to export it as Postman v2.1. Use "Export workspace" in the toolbar to save everything as a GWT Workspace JSON for full backup.
How does auto-save work?
Your workspace is saved to your browser's localStorage automatically — 30 seconds after your last change. An amber "Unsaved" chip appears while changes are pending; click it to save immediately. Your work is restored exactly as you left it when you return.