An API client as a browser extension

Open the browser, send the request. No Electron app, no installer, no administrator rights.

PolyApiIDE runs inside the browser rather than beside it. That changes three practical things: how it is installed, where the data sits, and what the browser sandbox will and will not allow. The limitations are listed here too, not buried.

What that buys you

  • Install without admin rights. On a locked-down work machine an extension installs where a desktop installer will not.
  • No second window. Your frontend, DevTools and the API client are all in the same browser — one tab away.
  • Data in the browser profile. Collections, environments and tokens are stored locally, alongside the profile, not in a vendor cloud.
  • The same tool across browsers. Chrome, Edge, other Chromium browsers and Firefox.
  • Updates through the store. No version to track by hand; with a lifetime licence new builds also land in the archive immediately, without waiting for store review.

Where it runs

BrowserStatusInstall from
Google Chrome Primary platform, MV3 Chrome Web Store
Microsoft Edge Supported Chrome Web Store
Other Chromium browsers Supported Chrome Web Store
Mozilla Firefox Supported Firefox Add-ons
Safari Not supported —

Install buttons for your browser are at the bottom of this page.

What the browser will not let it do

The sandbox buys safety and costs capability. So you do not discover this mid-task:

  • gRPC only via JSON transcoding. A native gRPC channel and streaming are not available from a browser; the service needs a gateway such as grpc_json_transcoder or grpc-gateway.
  • WebSocket handshake headers cannot be set. That is a browser API limitation, not an extension one. Tokens go through a query parameter, a cookie or a subprotocol.
  • No request signing. If your regulation requires a digital signature on the request, sign it outside the extension.
  • Load generation is bounded by the browser. Load profiles exist, but this is not a distributed generator, and HTTP/1.1 caps connections per host. For tens of thousands of requests per second use k6 or JMeter.
  • No CLI and no CI mode. Runs are started from the interface.

Install and first request

1. Install the extension

From your browser store. No site account and no key — the free tier is active immediately.

2. Open the workspace

Click the extension icon in the browser toolbar. Create a space and an environment holding your API base URL.

3. Send a request

Method, URL, headers, body. {{var}} and {var} substitution from the environment works in the URL and in headers.

4. Bring in existing collections

Import a Postman export, an OpenAPI spec, a WSDL, or just paste a curl command. All of that is on the free tier.

Frequently asked

What permissions does it request, and why?

Permissions are needed to send requests to arbitrary hosts and to store collections locally. The data actually processed is listed in the privacy policy, linked in the footer.

Can it reach localhost and services on my LAN?

Yes, requests to local addresses work. If a service answers with a CORS error, configure CORS on the service — the browser enforces that before the extension sees anything.

Does data sync between my browsers?

No, there is no automatic sync. Moving collections is an explicit export and import. That is deliberate: by default nothing leaves the device.

If I remove the extension, do I lose my collections?

Yes, along with the local storage. Export before removing the extension or wiping the profile.

Is there a desktop version?

No. The product exists as a browser extension, and that is the point: nothing is installed into the operating system.

See also

Chrome Web Store Firefox Add-ons
Quick start Watch the tour Pricing