Request inspector - Debug web hooks, http clients

RainforestQA - Insanely simple testing. Create tests for your website in plain English, then run them across all major browsers with a single click. Powered by human intelligence

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.

Bitrise - Tens of thousands of agencies, startups and enterprise companies with mobile apps - including Runkeeper, Grindr, Duolingo and more - use Bitrise to automate their way to increased productivity & speed

MockServer - Easy mocking of any system you integrate with via HTTP or HTTPS.

Cypress.io - Slow, difficult and unreliable testing for anything that runs in a browser. Install Cypress in seconds and take the pain out of front-end testing.