TaskPaper - Plain text to-do lists for Mac
MockServer - Easy mocking of any system you integrate with via HTTP or HTTPS.
Thrive - Thrive is an intuitive tool to manage your business using the latest trends in Project Management, Dashboards, Customer Relationship Management & Accounting
Beeceptor - Unblock yourself from API dependencies, and build & integrate with APIs fast. Beeceptor helps you build a mock Rest API in a few seconds.
Simply.Digital - Goals & Tasks - Todo list to track your time & help set meaningful deadlines
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.