And alternatives.

Zapier Platform - open source

huginn/huginn - Create agents that monitor and act on your behalf. Your agents are standing by!

DataFire/DataFire - an open source framework for building and integrating APIs. It provides over 1000 integrations

Node-RED - Low-code programming for event-driven applications. NodeJS. Browser-based flow editing.

StackStorm - seems pretty powerful automation platform, probably more for dev/engr applications than personal

Beehive - an event and agent system, which allows you to create your own agents that perform automated tasks triggered by events and filters. It is modular, flexible and really easy to extend for anyone. It has modules (we call them Hives), so it can interface with, talk to, or retrieve information from Twitter, Tumblr, Email, IRC, Jabber, RSS, Jenkins, Hue - to name just a few.

Standard Library - Use Standard Library to run custom workflows in response to events using APIs. Our products work together to automatically generate application code, host custom logic, and handle authentication across multiple apps.

Pipedream - Run any Node.js code, or use pre-built actions.

Microsoft Power Automate (Flow) - $15 user/month, unlimited flows

IFTTT - free for basic usage.

Quora: What are some alternatives to Zapier

Product Hunt: Zapier Alternatives

Boomi - some of their stuff on GitHub

AlternativeTo Zapier that are Open Source - Min enterprise is 200 EU / month.