Glossary · Internet & Web

Web App (Web Application)

A web app is an interactive application delivered through a browser, such as webmail or an online store, as opposed to a mostly static informational website.

Updated October 6, 2026

A web app is software that runs in a web browser and relies on a server to handle logic and data. Examples include email clients, dashboards, online banking and project management tools.

Why it matters

The line between website and web app is blurry, but the distinction matters for monitoring and security. Web apps have logins, databases, background jobs and APIs, so a page returning 200 does not prove the app works. They need deeper checks, such as testing a login or an API endpoint.

Example

A brochure site shows the same pages to everyone. A web app such as an invoicing tool shows each user their own data, saves changes, and may update the screen using JavaScript calls to an API without reloading.

Common mistakes

  • Monitoring only the home page of an app whose critical flows are behind a login.
  • Treating every site with a contact form as a web app needing heavy infrastructure.
  • Forgetting that the front end and the API can fail independently.

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