Slack caches messages, images, and shared files so workspaces load fast, and that cache can grow large if you belong to busy channels. On Android you clear it in Settings; on iPhone you offload or reinstall; on desktop you can reset the cache from the app menu.
Short answer:
- Android: Settings > Apps > Slack > Storage & cache > Clear cache (safe; keeps you signed in).
- iPhone: Settings > General > iPhone Storage > Slack > Offload App, or reinstall.
- Desktop note: Help menu > Reset Cache and Restart (or Troubleshooting > Clear Cache).
- Avoid Clear storage / Clear data, which signs you out of every workspace.
Why Slack Uses So Much Storage
Slack is more than a chat app; it caches the message history, profile pictures, link previews, and every image, GIF, and file shared in the channels you open. If you are in multiple active workspaces, this cache can climb into the hundreds of megabytes or more.
The good news: this is all rebuildable data. Your messages and files live on Slack's servers, so clearing the local cache only forces the app to re-download what it needs. You will not lose conversation history or shared files.
Clear the Slack Cache on Android
Android's storage screen is the cleanest method on a phone.
- Open Settings > Apps.
- Scroll to and tap Slack.
- Tap Storage & cache.
- Tap Clear cache.
You stay signed in to all your workspaces and the freed space registers immediately. If you have notification or sync glitches, this often fixes them too.
Important: the same screen has Clear storage (or Clear data). That resets Slack to a fresh install, signing you out of every workspace and clearing any unsent message drafts. You will need to re-add each workspace and sign in again. Use it only if Slack is broken. See clear cache vs clear data on Android and how to clear app cache on Android safely.
Clear Slack Storage on iPhone
iOS has no per-app cache button, so use one of these:
- Offload App: Go to Settings > General > iPhone Storage > Slack and tap Offload App. This removes the app and its cache but keeps your data, so reinstalling restores your sign-in.
- Delete and reinstall: For a complete purge, delete Slack and reinstall it from the App Store, then sign back in to your workspaces.
To see how much space Slack and other apps use on iPhone, a Clenoir storage scan lists them clearly and lets you confirm each cleanup before it happens.
Reset the Slack Cache on Desktop
If you also run Slack on a desktop, it has a built-in cache reset.
- In the Slack desktop app, open the Help menu in the top menu bar.
- Choose Troubleshooting > Clear Cache and Restart (older versions show Reset Cache and Restart).
- Slack closes, wipes its local cache, and relaunches signed in.
This is handy when desktop Slack feels sluggish or images stop loading, and it keeps you logged in.
Does Clearing the Cache Delete Messages or Files?
This is the most common worry, so it is worth being clear: no. Slack stores your message history, channels, and every uploaded file on its servers, tied to each workspace. Clearing the local cache only removes the copies your phone downloaded for quick access.
After you clear it, the first time you open a busy channel it will take a moment to re-fetch recent messages and images. That brief reload is the only downside, and it is well worth the space you reclaim. The one thing to protect is an unsent draft sitting in a message box, which lives locally; a plain Clear cache leaves drafts alone, but Clear storage / Clear data would wipe them along with your sign-in. As long as you stick to Clear cache, nothing you care about is at risk.
Reduce Slack's Storage Footprint Going Forward
A few settings keep the cache from ballooning again.
- In Slack's mobile settings, turn off autoplay for animated images and GIFs so fewer assets cache.
- Leave or mute inactive workspaces and channels you no longer follow.
- Clear the cache once a month if you use Slack heavily across several workspaces.
Slack is rarely the single largest app on a phone, so if you are still short on space, look wider. The clean up phone storage hub and the clear cache for all apps at once guide help you sweep every heavy app in one sitting, which is where the real gigabytes usually hide. Clearing Slack's cache is safe, takes under a minute, and keeps it responsive.
FAQ
How do I clear the Slack cache on Android?
Open Settings > Apps, tap Slack, tap Storage & cache, then tap Clear cache. You stay signed in to all your workspaces and the freed space registers immediately, which often fixes notification or sync glitches too.
How do I reset the Slack cache on the desktop app?
In the desktop app, open the Help menu in the top menu bar and choose Troubleshooting > Clear Cache and Restart (older versions show Reset Cache and Restart). Slack closes, wipes its local cache, and relaunches still signed in.
Does clearing the Slack cache delete my messages or files?
No. Slack stores your message history, channels, and every uploaded file on its servers, so clearing the local cache only removes downloaded copies. The one local item to protect is an unsent draft, which a plain Clear cache leaves alone but Clear storage would wipe.