Updated 2019-03-26: allow to pass up to 7 values instead of 3.
I am a heavy Zapier user, and I needed to send data to a Zapier webhook to trigger a workflow.
Thanks to Jamie Shaw's work on the IFTTT Webhook plugin, I could create a similar action for Zapier, here it is.
Zapier WebHook POST.zip (6.4 KB)
To use it, simply enter the full URL of the Zapier Webhook (in my example the last part is blurred, but you should enter the full URL given by Zapier), then you can pass up to seven values to the webhook.