Why can I not reach my localhost?
This tool cannot access localhost, or any endpoint behind your firewall or VPN, because it runs on the internet rather than on your computer. To reach one, sign in to Postman and use either the Postman Desktop App or the Desktop Agent in the web app. Both run on your own machine: the request goes straight from your computer to your endpoint, and your request data and credentials never pass through Postman's cloud.
Why can't I access my API through this tool?
This tool runs on the public internet, so it can only reach endpoints that are publicly reachable. One behind a corporate firewall, a VPN, a private network, or an IP allowlist will fail here, the same way localhost does, even if it works fine in your own browser. To reach it, sign in to Postman and use either the Postman Desktop App or the Desktop Agent in the web app. Both execute locally on your own machine, so they can reach anything your network can reach, and your request data and credentials never leave your machine or pass through Postman's cloud.
Does REST API Client use the Desktop Agent?
No. This standalone workbench executes requests only through Postman Cloud Agent and needs no installations.
Can I save a request without an account?
You can build and send the request while signed out; To save your requests to a collecton and collaborate with teammates, sign in or create a free Postman account.
Does the playground resolve workspace variables?
No. Workspace state, variable resolution, history, and agent selection are available post signing up.