Session Storage
What does session storage mean?
Session storage is a browser-based mechanism that allows websites to store data temporarily on a user’s device for the duration of a single browsing session. Unlike cookies, which can persist for days or even years, session storage data exists only as long as the browser tab or window remains open. Once the tab is closed, the stored information is automatically deleted. This feature helps websites remember temporary states—such as form entries, page progress, or in-session preferences—without creating long-term records or transmitting data to servers unnecessarily.
How does session storage work?
Session storage operates through the browser’s Web Storage API, a JavaScript interface that lets developers store and retrieve small pieces of data known as key-value pairs.
- Tab-specific storage: Each tab or window has its own isolated storage area, meaning data stored in one tab cannot be accessed by another, even on the same website.
- Local operation: The stored data remains entirely on the user’s device and is not sent to the website’s servers with each request, which improves speed and reduces bandwidth usage.
- Larger capacity: Session storage can hold significantly more data than cookies—typically up to 5–10 MB per domain.
- Automatic deletion: The data is erased automatically when the user closes the tab or window, making it ideal for temporary state management.
Common use cases include:
- Remembering user input in a form so it’s not lost if a page reloads.
- Maintaining the state of a multi-step checkout process.
- Storing temporary authentication tokens during a session.
- Keeping application data in single-page web apps without server calls.
Why is it important?
Session storage offers developers a lightweight, privacy-friendly alternative to cookies for managing short-term data. Because it does not automatically transmit information to servers or persist beyond the session, it reduces exposure of personal data and can improve website performance.
However, privacy considerations still apply. If session storage is used to collect behavioral data, analytics, or identifiers that could track users—even temporarily—it may require consent under privacy laws such as the GDPR or ePrivacy Directive. Businesses should clearly document its use in their privacy or cookie notices and restrict it to purposes necessary for delivering the service users expect.
FAQs about session storage
Not if it is used for essential purposes, such as keeping form inputs during a session. But if used for tracking or personalization, consent may be required.
Cookies can persist across sessions and are sent with every server request. Session storage is local, larger in capacity, and cleared when the session ends.
No. Session storage is isolated to the specific domain and tab where it was created.
It avoids persistence and server transmission but is still vulnerable to XSS if sensitive data is stored.
Preserving form inputs, caching temporary app data, and storing short-lived authentication tokens.