LocalStorage is a web storage API that allows websites to store key-value pairs persistently in a user's browser. Unlike cookies, data in localStorage is not sent to the server with every HTTP request. It's domain-specific, meaning each website can only access its own stored data. Data survives browser restarts and remains available until explicitly deleted by the user or the website.

Most modern browsers limit localStorage to approximately 5-10 MB per domain. The typical limit is 5 MB (5,242,880 bytes). This tool shows your current usage and estimated remaining space. If you exceed the quota, any setItem() call will throw a QuotaExceededError. Note that localStorage uses UTF-16 encoding, so each character takes 2 bytes of storage.

Yes, localStorage data is persistent. It remains stored even after closing all browser tabs or restarting the computer. Data only gets cleared when: (1) the user manually clears browser data, (2) the website deletes it via JavaScript, (3) the user is in private/incognito mode (data is cleared when the session ends), or (4) the browser's storage is full and evicts older data (rare).

This tool makes it easy: click "Export JSON" to download all key-value pairs as a formatted JSON file. To restore or transfer data, click "Import JSON" and select a previously exported file. The import will merge data into your current localStorage, overwriting any keys that already exist. This is useful for backing up data, migrating between browsers, or sharing configuration between devices.

Editing localStorage values is generally safe, but you should be cautious. Many websites store critical configuration, authentication tokens, or application state in localStorage. Changing a value to an invalid format could break the website's functionality. Always consider exporting your data before making significant changes. Only edit values if you understand what they represent and the expected format.

The key difference is persistence: localStorage data survives browser restarts and persists indefinitely until manually cleared. sessionStorage data is cleared when the browser tab or window is closed. Both have similar APIs (getItem, setItem, removeItem) and similar storage limits (~5 MB). Use localStorage for long-term data and sessionStorage for temporary, session-only data.

No, once localStorage data is deleted (via removeItem() or clear()), it cannot be recovered through the browser. There is no built-in recycle bin or undo feature for localStorage. This is why we recommend exporting your data as a backup before performing any delete or clear operations. The exported JSON file serves as your safety net.

Yes, localStorage does work in private/incognito mode in most modern browsers, but with an important caveat: the data is tied to the private session and is automatically deleted when all private windows are closed. Some older browsers may block localStorage entirely in private mode. The storage limit in private mode may also be reduced.

You can calculate localStorage usage by iterating over all keys and summing the character lengths of both keys and values, then multiplying by 2 (since JavaScript uses UTF-16 encoding). Example:
let total = 0; for (let key in localStorage) { total += (key.length + localStorage.getItem(key).length) * 2; }
This tool automatically displays your usage with a visual progress bar for easy monitoring.