Shopify
Three routes, depending on whether the reviews already exist somewhere else, live in your store, or do not exist yet.
How to add reviews to a plain HTML site
The exact steps for HTML, in about five minutes, without a developer.
The short answer
Build a widget, copy one line of code, and paste it into the code, pasted where the reviews should appear. your HTML file or template. No developer and no theme files.
Step by step
Build the widget and connect your review sources
Choose a layout and match the colours to your site
Copy the embed code
In HTML: your HTML file or template
Add the code, pasted where the reviews should appear and paste the code
Save and check the live page
Where to put them
Exactly where you paste it. For floating layouts the position is set in the widget rather than by where the code sits.
Full-width sections suit carousel and grid layouts; narrow columns suit a badge.
Does HTML have reviews built in?
No. HTML has no built-in review system, so reviews come from an embed or a third-party tool.
If your reviews already live on Google or a marketplace, nothing built into a site builder will reach them.
If they do not appear
A content security policy on the server blocking the script. The browser console will say so explicitly.
The HTML troubleshooting page works through the rest in order.
Questions
Other setup guides
Any website
Whether your reviews already exist somewhere else, live in your store, or do not exist yet — three different answers.
WordPress
The exact steps for WordPress, in about five minutes, without a developer.
Wix
The exact steps for Wix, in about five minutes, without a developer.