While we recommend using Google's official client libraries wherever possible for application development, the REST interface can be useful in cases where you just want to issue a one-time request to the Google Ads API, for instance when you want to test the behavior of an endpoint or to debug a request.
For these situations, the reference pages for REST endpoints provide a Try it! button which you can use to send a single request to the Google Ads API to verify its behavior.
To use it, you need your developer token and the customer ID for the account you want to issue the request against. Access to that account is also required since you have to authenticate with a Google account using OAuth.
Once you have these, you can visit a REST reference page, like the one for the
customers.googleAds/search
endpoint, and click the Try it! button on the right to send your request.