Hi @amonphi,
since the API key has to be included in the request header, instead of the query parameter, the preferred way to test our API in the browser should be by using our documentation environment.
But there are some other ways, which I would recommend for testing, like Posman which allows you to modify your headers and also generates code snippets in specified languages if needed.
Snímek obrazovky 2023-10-02 v 17.17.59.png