Slack has a cache that it uses to store messages you've read recently, so it can load those messages faster in the future. And the space that those messages take up on your device — especially if they have pictures or links attached — can add up quickly.
If Slack is running slowly, or taking up more storage space than it usually does, you should clear the cache. Every version of the Slack app has a different process for this, but it shouldn't ever take long.
How to clear Slack's cache on your Mac or PC
The Slack desktop apps — the ones you download onto a Mac or PC — let you clear the cache through the Help menu. This is located in different spots depending on your operating system.
If you're on a Mac, open Slack and click Help in the toolbar at the top of your screen. Hover your mouse over the Troubleshooting option, and then select Clear Cache and Restart.
If you're on a PC, open Slack and click the three stacked lines in the top-left corner of the window. Hover your mouse over Help, then Troubleshooting. Click the Clear Cache and Restart option.
When you click that option, Slack will shut down and then reopen itself. Once it restarts, your cache will be cleared.
How to clear Slack's cache on an iPhone or iPad
Unlike other devices, iPhones and iPads don't usually let you clear app caches manually. The only way to clear most app caches on an iPhone or iPad is to delete the app, and then reinstall it.
Slack is one of the rare exceptions. There are two ways to manually clear the Slack app's cache on an iPhone or iPad: Through the Slack app itself, or through your device settings.
First off, you can open the Slack app and tap the You option in the bottom-right corner. Select Preferences at the bottom, then Advanced. Tap the red Reset Cache option at the very bottom of the page.
Secondly, you can open the Settings app and scroll down to tap Slack. Once there, toggle on the Reset Cache on Next Launch switch. Once this is flipped on, Slack's cache will clear the next time you open the app.
How to clear Slack's cache on an Android
Android phones and tablets let you clear any app's cache through the device's Apps menu.
Open your Android's Settings app and tap the Apps option. Select All apps, then scroll down to tap the Slack option. Tap Storage & cache, and finally tap Clear cache.
