What cookies are and why you might want to delete them
Cookies are small files that websites store on your computer to remember information about you — your login details, what you put in a shopping cart, your preferences for how a site looks. They make browsing faster and more convenient. But they also mean websites can track which pages you visit and when, and advertisers can follow you across different sites to show you targeted ads.
Deleting cookies clears out this stored information. After you delete them, websites won't remember you the next time you visit, so you may need to log back in. Advertisers also lose the ability to track your movement across the web. Some people delete cookies regularly for privacy; others do it only when they notice a site behaving oddly or when they're selling a device.
Mozilla Firefox stores cookies in a specific location on your computer, and the browser gives you several ways to remove them — you can delete all of them at once, delete only the ones from certain websites, or set Firefox to delete them automatically every time you close the browser.
Key Takeaways
- You can delete all cookies at once through Firefox's Settings menu under Privacy & Security, or delete cookies from individual websites through the address bar.
- Deleting cookies will log you out of most websites and remove any saved preferences, so you will need to log back in the next time you visit.
- Firefox can be set to delete cookies automatically when you close the browser, which removes the need to do it manually.
- Clearing cookies does not delete your browsing history, passwords, or other saved data unless you specifically choose to clear those as well.
Delete all cookies at once through Settings
Open Firefox and click the menu button — three horizontal lines in the top right corner of the window. Select Settings from the dropdown menu.
On the left side of the Settings page, click Privacy & Security. Scroll down until you see the section labeled Cookies and Site Data. You will see a button that says Clear Data. Click it.
A window will pop up with checkboxes for different types of data. Make sure the box next to Cookies and Site Data is checked. You can leave the other boxes unchecked if you only want to delete cookies. At the bottom of the window, click Clear. Firefox will delete all cookies when ready.
Delete cookies from a specific website
If you only want to remove cookies from one website rather than all of them, you can do this directly from the address bar. Go to the website you want to clear cookies from, then click the lock icon or information icon to the left of the web address at the top of the browser.
A small panel will appear. Click the arrow or expand button next to Connection or Cookies — the exact label depends on your Firefox version. You will see a list of cookies stored for that site. Click the trash icon next to each cookie you want to delete, or look for a button that says Remove All to delete them all at once.
Set Firefox to delete cookies automatically when you close the browser
If you want Firefox to clean up cookies without you having to remember to do it manually, you can set the browser to delete them every time you close it. Open Settings and go to Privacy & Security again.
Under the Cookies and Site Data section, you will see a checkbox that says Delete cookies and site data when Firefox is closed. Check this box. From now on, Firefox will automatically delete all cookies the moment you close the browser window completely — not just when you close a single tab.
Keep in mind that if you turn on this setting, you will be logged out of websites every time you close Firefox, even if you normally stay logged in. You can add exceptions for websites you want to stay logged into by clicking Manage Exceptions in the same section and typing in the website address.
Understand what gets deleted and what stays
When you delete cookies through Firefox Settings, you are only removing the cookies themselves — the small files websites use to remember you. This does not automatically delete your browsing history, saved passwords, autofill information, or cached images and files.
If you want to delete those things too, you can check the additional boxes in the Clear Data window before clicking Clear. But if you only want cookies gone, leave those boxes unchecked. This matters because deleting your saved passwords means you will have to type them in from memory next time you log in, which can lock you out if you do not remember them.
Troubleshoot if cookies keep coming back
Sometimes after you delete cookies, they reappear the next time you visit a website. This happens because the website when ready creates new cookies when you land on it — this is normal behavior and not a sign that something went wrong. The old cookies are gone; the website is straightforward making new ones.
If a website is behaving strangely even after you delete its cookies, try clearing the site data as well. Go back to the website in the address bar, click the lock icon, and look for an option to clear site data or storage. This removes more than just cookies and can sometimes fix login problems or pages that load incorrectly.
If you have turned on the setting to delete cookies when Firefox closes, but you notice you are still logged into websites the next time you open Firefox, check whether you added that website to the Exceptions list. Sites on the exceptions list will keep their cookies even when the automatic deletion runs.
Frequently Asked Questions
Will deleting cookies delete my saved passwords?
No. Cookies and passwords are stored separately. When you delete cookies, your saved passwords stay in Firefox unless you specifically check the box to clear passwords in the Clear Data window. However, deleting cookies will log you out of websites, so you will need to log back in with your password.
Can I delete cookies from just one website without affecting others?
Yes. Click the lock or information icon in the address bar while you are on that website, then delete the cookies listed there. This removes only that site's cookies and leaves cookies from other websites untouched.
What happens if I delete cookies from a website I use regularly?
You will be logged out the next time you visit, and the site will not remember your preferences. You can log back in, and the site will create new cookies. If you do not want to keep deleting cookies from sites you use often, add them to the Exceptions list so Firefox skips them during automatic deletion.
Does deleting cookies improve Firefox performance or speed?
Deleting cookies frees up a small amount of storage space on your computer, but the impact on browser speed is usually not noticeable. The main reason to delete cookies is privacy — to stop websites and advertisers from tracking your activity — not to make Firefox run faster.
Can websites see that I deleted their cookies?
No. Once cookies are deleted, they are gone from your computer. Websites cannot tell whether you deleted them or whether you never visited in the first place. They only know that the next time you visit, there are no cookies to read.