What are some alternatives?
When comparing Node-RED and Microsoft Flow, you can also consider the following products
n8n.io - n8n is a free node-based "Open Source" (with Commons Clause) Workflow Automation Tool.
ifttt - IFTTT puts the internet to work for you. Create simple connections between the products you use every day.
Zapier - Connect the apps you use everyday to automate your work and be more productive. 1000+ apps and easy integrations - get started in minutes.
Integromat - Tool for workflow automation
Git Butler - Pull Request and Issue Workflow Automation
Airflow - Airflow is a platform to programmaticaly author, schedule and monitor data pipelines.