Only BurpSuite Professional has the collaborator, and costs a lot. ZAP does not include OAST functionality. And there are alternatives:
pingb.in was originally for capturing ICMP pings with a unique payload, it works great for DNS and HTTP too. It does not seem to support HTTPS though.
The Webhook.site supports inspecting, testing and automating (with the visual Custom Actions builder, or WebhookScript) incoming HTTP request sor e-mail.