ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.
Webhook.site - Instantly generate a free, unique URL and email address to test, inspect, and automate (with a visual workflow editor and scripts) incoming HTTP requests and emails.
Pipedream - Integration platform for developers
Hookdeck - Hookdeck makes it simple to build and deploy reliable, testable, and debuggable applications that rely on webhooks.
Parabola - Automate manual processes without spreadsheets or code
Svix - The enterprise ready webhooks service, open-source and in the cloud.