Site or App?

Fluid hosts two kinds of project. Most projects should be a site. Pick an app only when the project needs something a site can’t do.

The rule

Make it a site, unless it needs one of these:

The project needs	Make it	Why
Its own domain, such as `events.yoli.com`	App	Sites live at your company’s addresses and have no custom domain
Rendering at request time, such as a Next.js app with dynamic server rendering, server actions, middleware or route handlers that run on each request	App	A site serves the files your build wrote
Server code: long jobs, large dependencies, a Postgres database	App	A site serves files, and site functions aren’t available yet

Everything else is a site: landing pages, event pages, calculators, forms, small dashboards, anything a static build with the site database can do.

Side by side

	Site	Mist app
Code	Any static build: Vite, Astro, plain HTML, Next.js static export	Next.js, from Fluid’s starter
Deploy	`fluid deploy`	Push to the app’s repository
Database	`fluid.db`, tables in `db/schema.json`	Its own Postgres
Server code	None yet: functions are coming	Full Next.js server
Address	Your company’s storefront, at `/sites/<handle>`	Your own domain, or Fluid’s
Read more	Sites quickstart	Mist apps

Changing your mind

A public company site that outgrows these limits can be converted into an app, which starts from the site’s code. See Convert a site to an app.

Ask Fluid

Recommend a site or an app for a new project applies the same rule to a description of what you’re building. It reads and changes nothing, and needs application_themes.view.

curl -X POST https://api.fluid.app/api/company/v2026-10/project-launch-recommendations \
  -H "Authorization: Bearer $FLUID_TOKEN" \
  -H "Content-Type: application/json" \
  -d '{"description": "An event page for our spring launch, on launch.example.com", "needs": {"custom_domain": true}}'

{
  "kind": "app",
  "reasons": [
    { "code": "custom_domain", "message": "It needs its own domain. Sites live at a Fluid address, and apps can have a custom domain" }
  ],
  "status": 200,
  "meta": { "request_uuid": "…", "timestamp": "…" }
}

needs takes custom_domain, server_rendering and heavy_functions. A need you leave out is read from plain phrases in the description, such as “its own domain”. A need you set to false isn’t. kind is site or app. fluid deploy asks it when it finds a Next.js app with a server, and prints the answer with the reasons.

Get started

Sites

Mist apps

Core concepts

Guides

Guided setup

Storefront guides

SDKs

Portal & Widgets

Site or App?

The rule

Side by side

Changing your mind

Ask Fluid

​The rule

​Side by side

​Changing your mind

​Ask Fluid

The rule

Side by side

Changing your mind

Ask Fluid