Zapier is automation software; it listens or waits for certain things to happen (events) and when they occur it fires off a recipe of actions.
Actions can be simple things like sending emails or complicated things like updating databases, updating e-commerce orders, translating websites or sending API calls.
Many of the websites I make for my clients simply depend on Zapier to send contact form data but there are more powerful recipes that I have created that integrate with external apps such as Webflow, Airtable and Xero. Zapier undertakes tasks in these instances to listen to certain events in these apps and then run through a series of standard procedures to update data and notify recipients.
Zapier’s interface is a linear step-by-step approach, you build up your automation in a step by step environment. They have built in tools to filter, transform and email information and you can create ‘paths’ that act out alternative actions based on conditions.

Zapier is one of the easier automation platforms to use and as a result it has limitations. Parabola and Integromat are alternatives that fill some of the gaps; they both share a similar interface setup resembling flowcharts rather than as Zapier’s step-by-step linear approach. I find the former’s approach easier to understand when everything is clearly mapped out in front of you. Zapier’s approach tends to display conditional paths as collapsed entities so it’s hard to see the follow on tasks in these paths. For a form based / linear approach, Automate.io is also a good alternative.
Zapier’s pricing plans offer fair options ranging from between free to £70 per month, depending on use case requirements; in my case as I depend on conditional tasks, I use the professional plan.