Why Slack quietly eats your disk — and how to slim it down

Q: Will clearing Slack cache log me out?

No. Using Slack's built-in Clear Cache and Restart keeps your login sessions intact. Only deleting the entire Application Support folder would log you out.

Q: Does Slack cache grow back after clearing?

Yes — Slack re-caches data as you use it, which is normal. But re-cached data is smaller initially. Clearing every month or two keeps the size manageable.

Updated September 2026 · 6 min read

Slack runs all day for millions of people, which means it has all day to accumulate data on your Mac. Between cached messages, downloaded files, preview images, and application logs, Slack can grow to 3–8 GB without any obvious reason. If you're in multiple workspaces, multiply that.

The good news: most of what Slack stores is cache and temporary data, meaning it's entirely safe to clear. Here's how.

What Slack stores on your Mac

Slack keeps several types of data locally:

Service Worker cache: cached messages, channel data, and UI assets for fast loading. This is usually the biggest chunk.
Downloaded files: any file you've clicked to download or preview stays in Slack's data folder.
Image and link previews: thumbnails and preview cards for every link and image shared in your channels.
Logs: diagnostic logs that Slack writes continuously. These can grow surprisingly large over time.

All of this lives inside ~/Library/Application Support/Slack and ~/Library/Caches/com.tinyspeck.slackmacgap.

How to clear Slack cache on Mac

Method 1: Use Slack's built-in cache reset

Slack has a built-in option that clears its cache and reloads:

Open Slack.
Click Help in the menu bar.
Select Troubleshooting → Clear Cache and Restart.

Slack will close, delete its cached data, and reopen. You'll stay logged in to all your workspaces — it just needs a moment to re-sync recent messages and channels. This is the easiest and safest approach.

Method 2: Clear cache files manually

If you want more control, or if Slack's built-in option didn't free enough space:

Quit Slack completely (Cmd + Q).
In Finder, press Cmd + Shift + G and go to ~/Library/Application Support/Slack.
Look for folders named Cache, Code Cache, Service Worker, and GPUCache.
Delete the contents of these folders (not the folders themselves).
Also check ~/Library/Caches/com.tinyspeck.slackmacgap and clear it.

When you reopen Slack, it will rebuild these folders. Your workspaces, channels, and login sessions are stored separately and won't be affected.

When not to do this: don't delete the entire Application Support/Slack folder — it contains your workspace authentication tokens alongside the cache. Removing everything would log you out of all workspaces. Only clear the cache-specific subfolders listed above.

Multiple workspaces = multiple caches

If you belong to several Slack workspaces (personal, work, community), each one maintains its own cached data. This is a common reason Slack's footprint feels disproportionately large. The "Clear Cache and Restart" option handles all of them at once.

Slack logs: the forgotten space eater

Slack writes diagnostic logs that most people never look at. Over months, these can grow to several hundred megabytes — sometimes more. They live inside ~/Library/Application Support/Slack/logs. You can safely delete old log files (anything more than a few days old) without affecting Slack's operation.

Consider the web version

If your Mac is tight on space, using Slack in a browser instead of the desktop app eliminates the separate cache entirely. The browser version is fully featured, and its cache is managed along with all your other browser data — which you can clear easily.

Every app's cache, one clear view

Gigatidy scans your Mac and finds the caches that are actually worth clearing — Slack, browsers, messengers, and everything else — then handles the cleanup with your approval.

Meet Gigatidy →

FAQ

Will clearing Slack cache log me out?

No. Using Slack's built-in "Clear Cache and Restart" keeps your login sessions intact. Only deleting the entire Application Support folder (which you shouldn't do) would log you out.

How much space does Slack use on Mac?

The app itself is around 500 MB. Cached data typically adds 2–5 GB on top of that, depending on how many workspaces you're in and how long Slack has been running. Heavy users with multiple workspaces can see 5–8 GB total.

Does Slack cache grow back after clearing?

Yes — Slack re-caches data as you use it, which is normal behavior that helps it load channels faster. But re-cached data tends to be smaller initially. Clearing the cache every month or two keeps the size manageable.