Cache Control Guide

What cache does

Your browser saves copies of images, scripts and other files so that websites load faster next time you visit. Most of the time this is helpful. However, after we deploy a fix or update, your browser can keep showing you an old version of a page even though the live site has already changed.

Cache, cookies and history

• Cache is the saved files used to load a site more quickly.
• Cookies are small data files that remember things like logins, baskets and preferences.
• History is just the list of pages you have visited.

Clearing history alone is not enough. To see the latest version of the site you must clear cached files and often cookies as well.

Important nuances on desktop and mobile

• Open tabs can hold on to old data. If you have the site open in a tab and clear cache, that tab may keep using the old version until you close it and open a new tab.
• Browsers keep some data in memory. On all devices it is best to close every tab for the site, clear cache and cookies, fully close the browser, reopen it and then visit the site again.
• Mobile apps must be closed properly. On Android and iOS you should swipe the browser away in the app switcher so it fully closes, not just minimise it.
• Different browsers have different data. Chrome, Safari and Edge all save their own cache. An issue in one browser might not show in another, which is why we often ask you to test more than one.

If you work on your own website regularly, your browser builds up far more cached files and stored data than a normal visitor. This means you’re statistically much more likely to see an outdated version of a page after we deploy a change. Your customers don’t use the site as heavily or repeatedly during update windows, so the risk of them seeing an old version is extremely low. In almost every case, the ‘issue’ only appears for internal users with long-lived browser data, clearing cache, cookies and reopening the browser resolves it immediately.

Use these steps on Windows 10 and Windows 11 when you use Google Chrome or Microsoft Edge.

Chrome on Windows

1. Close any tabs where your site is open.
2. Press Ctrl + Shift + Delete to open Clear browsing data.
3. Set Time range to All time when testing a fix.
4. Tick Cookies and other site data and Cached images and files.
5. Click Clear data.
6. Fully close Chrome, then reopen it and load the site again in a new tab.

Edge on Windows

1. Close any tabs where your site is open.
2. Press Ctrl + Shift + Delete to open Clear browsing data.
3. Choose All time for the time range.
4. Tick Cookies and other site data and Cached images and files.
5. Click Clear now.
6. Fully close Edge, then reopen it and visit the site again.

If you prefer not to clear your main browser, you can install an alternative such as Firefox and keep it just for testing. In that test browser you can safely clear cache and cookies as often as needed.

Use these steps on Mac desktop and laptop devices when you use Safari or Google Chrome.

Safari on macOS

1. Close any tabs where your site is open.
2. In the top menu click Safari then Settings… (or Preferences…).
3. Open the Privacy tab.
4. Click Manage Website Data… then Remove All to clear cookies and cached data.
5. Click Done, then press Cmd + Q to fully quit Safari.
6. Reopen Safari and visit the site again in a new tab.

Chrome on macOS

1. Close any tabs where your site is open.
2. Press Cmd + Shift + Delete to open Clear browsing data.
3. Choose All time as the time range.
4. Tick Cookies and other site data and Cached images and files.
5. Click Clear data.
6. Press Cmd + Q to fully quit Chrome, then reopen it and load the site again.

If you use iCloud to sync Safari across devices, clearing data may also affect your history on other Apple devices signed in with the same Apple ID.

Use these steps on Android phones and tablets when you use Chrome or Edge.

Chrome on Android

1. Close all tabs where your site is open.
2. Tap the three dots in the top right and choose History then Clear browsing data….
3. Set Time range to All time for testing.
4. Tick Cookies and site data and Cached images and files.
5. Tap Clear data and confirm.
6. Use the app switcher to swipe Chrome away so it fully closes, then reopen it and visit the site again.

Edge on Android

1. Close all tabs where your site is open.
2. Tap the three dots menu and go to Settings then Privacy and security.
3. Tap Clear browsing data.
4. Choose All time as the time range.
5. Tick Cookies and site data and Cached images and files.
6. Tap Clear now, then fully close and reopen Edge.

If you prefer not to clear your main mobile browser regularly, consider installing a second browser such as Firefox and keeping it purely for testing.

Use these steps on iPhones and iPads when you use Safari or Chrome.

Safari on iOS and iPadOS

1. Close all tabs where your site is open.
2. Open the Settings app and scroll down to Safari.
3. Tap Clear History and Website Data.
4. Select the relevant time period, then confirm.
5. Alternatively, to clear only website data, go to Safari then Advanced then Website Data and tap Remove All Website Data.
6. Use the app switcher to swipe Safari away so it fully closes, then reopen it and visit the site again.

Chrome on iOS and iPadOS

1. Close all tabs where your site is open.
2. Open the Chrome app and tap the three dots at the bottom or top of the screen.
3. Tap Settings then Privacy then Clear browsing data.
4. Choose All time as the time range when testing.
5. Tick Cookies, Site Data and Cached Images and Files.
6. Tap Clear browsing data and confirm, then fully close and reopen Chrome.

If you use iCloud Sync for Safari, remember that clearing data may also affect Safari history on your other Apple devices.

Use a dedicated test browser

We strongly recommend keeping a separate browser installed purely for testing changes to your site. For example you might:

• Use Chrome or Safari as your normal everyday browser.
• Install Firefox or Edge and use it only as a “clean” test browser.
• On mobile, install a second browser app and keep it for testing so you do not have to clear your main browser every time.

On your test browser you can safely clear all history, cookies and cache whenever we ask you to check a change. This makes it much more likely that you will see exactly what your customers see.

The “golden sequence” we ask you to follow

1. Close every tab where your site is open.
2. Clear cache and cookies using the instructions for your device and browser.
3. Fully close the browser app or programme.
4. Reopen the browser and visit the site again.
5. If the issue is still there, repeat the same in your dedicated test browser.
6. When you contact us, include a screenshot and tell us your device, browser, page URL and approximate time of the test.

This simple process removes almost all cache related differences between what you see and what we see, so we can confirm very quickly whether an issue is still live or has already been fixed.