If so, by rest client tool and advanced rest client do you mean that there's different request url in which the HubSpot Webhook will send webhook notifications to -- and you noticed that you're only receiving the Webhook notification on the rest client tool url but not the advanced rest client url?
I was able to get webhook call on my end now when creating a company, however when importing some companies, some requests is not being delivered through the hubspot webhook API, so not all companies are being registered on my system after the import. Could you please help me with that?
It's tough to say for sure what's going on without taking a look at your app settings, but it sounds like your event throttling is set too low. When this setting is set too low, and you experience a large influx of events, the rate limiting can result in timeouts that are retried seconds, minutes, or hours later.
Under normal circumstances, HubSpot will retry webhook notifications up to 10 times over 24 hours. You can find the details of our retry logic in the Webhook API documentation, and inthis changelog post.
I would recommend increasing your event throttling as a first step. It'd also be a good idea to check out your webhook requests in your app's "Monitoring" dashboard to see if there are any errors that might point to an underlying issue.