What Start does
Start shows the site at an address on this computer. Nothing is uploaded, no account is needed, and only this computer can open it. Which of three things happens depends on the project, and the preview card on the Overview tab says which:
- A folder of HTML is served as it is. The address shows the files in the folder, exactly as they are.
- A project with a build step — Vite, Astro, Eleventy, Create React App, Gatsby, anything with a
buildscript — is built first, and the copy the build made is what you see. Edit the source, press Start again. - A project with its own dev script, or one you chose in the Start button's menu, runs through that script:
npm run dev, with its live reload. This is how a Next.js project opens here while publishing it is not yet possible.
Stop takes it down. Quitting the app stops everything it started, and says so first.
Which folder is served
A repository often keeps its pages one folder down — public, site, docs — with configuration around them. The preview card has a Preview folder control for that: choose the folder the pages are in, and the preview, the thumbnail and everything else that looks at the site use it. A project with a netlify.toml that names its publish folder is settled from it without asking.
This governs the preview only. What a publish sends is still the whole project.
A name, with https
Any site running here can have a name instead of 127.0.0.1 and a port: my-shop.test, or whatever you type, ending in .test, .local, .localhost, .internal or .loc — endings no registry sells, so no real site can be shadowed. The row is on the preview card, and on the Docker card for PHP.
Adding one writes a line into your computer's hosts file, which is why the computer asks for your password once. The name then opens with https:// and a real padlock: the app is its own certificate authority, the way the mkcert tool works, and your computer trusts it after that permission. On a Mac that is a second dialog, from macOS itself, about trust settings. The trust is for this computer only. Firefox keeps a certificate store of its own and shows a warning.
A plain http:// request to the name is sent to https:// by default; the switch for that is in Settings, "Local names: https only". Removing the name removes the line, through the same permission.
Two ports are involved: 80 and 443, which a browser opens without being told. On Windows they are ordinary ports. On a Mac that keeps them for the administrator, the same permission sets up a redirect to the app's own ports instead; when another program holds them, the name keeps a port after it and the row says why.
Auto Scan
Auto Scan, at the bottom of the library, finds the sites already running on this computer's usual development ports — the dev server you started in a terminal last week — and shows which folder and project each belongs to. One you have not added yet can be added from there, after you confirm where it lives.