If you have opened Activity Monitor recently and noticed Slack using too much memory on your Mac, you are not imagining things. Slack is an Electron-based app — meaning it runs a full Chromium browser engine just to display your chat messages — and that architectural choice has real consequences for both RAM and disk space. On Apple Silicon Macs running macOS Sequoia or Tahoe, Slack regularly climbs past 500 MB of RAM and can quietly accumulate several gigabytes of cached data over months of daily use. This post explains exactly why that happens, where the files live, and how to reclaim the space safely without losing any messages or settings.
Why Slack Is an Electron App (And Why That Matters)
Electron apps bundle a copy of the Chromium rendering engine and a Node.js runtime. Every time you launch Slack, macOS must load that engine into memory before a single channel loads. On Intel Macs this has always been noticeable; on Apple Silicon Macs running the native arm64 build of Slack the footprint is smaller, but it is still significantly heavier than a purpose-built AppKit or SwiftUI application would be.
Beyond RAM, Electron apps generate the same kinds of browser cache that Google Chrome or Microsoft Edge accumulate: HTTP caches, IndexedDB stores, compiled shader caches, and GPU caches. Slack adds its own layer on top — downloaded file attachments, workspace icons, emoji packs, and call media — so the on-disk footprint grows even when you never consciously download anything.
Where Slack Stores Its Data on macOS
Slack spreads data across several ~/Library subfolders. Here is a breakdown of the main locations and what they contain:
| Path | Contents | Typical size |
|---|---|---|
~/Library/Application Support/Slack |
Workspace databases, user preferences, local message cache, downloaded files | 1 – 8 GB |
~/Library/Caches/com.tinyspeck.slackmacgap |
Chromium HTTP cache, thumbnail cache, shader cache | 200 MB – 2 GB |
~/Library/Caches/Slack |
App-level caches (emoji, avatars, workspace icons) | 50 – 500 MB |
~/Library/Saved Application State/com.tinyspeck.slackmacgap.savedState |
Window restoration state snapshot | 1 – 20 MB |
~/Library/WebKit/com.tinyspeck.slackmacgap |
WebKit storage used by in-app browser panels | 10 – 100 MB |
The Application Support/Slack folder is by far the largest because Slack keeps a local LevelDB database for every workspace you belong to. Each workspace gets its own subfolder. If you are in five workspaces and each has a busy channel history, it is not unusual to see 3–6 GB just in that one directory.
How to Check How Much Space Slack Is Actually Using
Before deleting anything, measure what you have. Open Terminal and run:
du -sh ~/Library/Application\ Support/Slack
du -sh ~/Library/Caches/com.tinyspeck.slackmacgap
du -sh ~/Library/Caches/SlackYou can also see Slack's combined footprint in System Settings. Go to System Settings > General > Storage, wait for the bar to populate, then click Applications. macOS bundles the app binary size and user data together there, so Terminal gives you a more granular picture.
For RAM, open Activity Monitor (in /Applications/Utilities/), click the Memory tab, and sort by Memory. Slack may appear as multiple helper processes — Slack Helper, Slack Helper (GPU), and Slack Helper (Renderer) — so add them all together for the real figure. On a busy workday the sum commonly reaches 600–900 MB.
How to Clear Slack's Cache and Reduce Disk Usage (Step-by-Step)
This section walks through the safest approach to reclaiming disk space. Clearing the caches listed below will not delete your messages, channels, or workspace membership — that data lives on Slack's servers and in the protected database inside Application Support/Slack.
- Quit Slack completely. Use Slack > Quit Slack from the menu bar, or run
killall Slackin Terminal. The app must not be running when you remove caches. - Clear the Chromium HTTP cache. Delete the folder at
~/Library/Caches/com.tinyspeck.slackmacgap. You can do this in Finder (hold Option, click Go > Library, then navigate to Caches) or in Terminal:rm -rf ~/Library/Caches/com.tinyspeck.slackmacgap - Clear the Slack-level cache. Delete
~/Library/Caches/Slack:rm -rf ~/Library/Caches/Slack - Remove saved window state. This is optional but low-risk:
rm -rf ~/Library/Saved\ Application\ State/com.tinyspeck.slackmacgap.savedState - Relaunch Slack. Slack will rebuild its caches as it fetches data. The first launch may feel slightly slower while it repopulates avatars and thumbnails.
If you want to reclaim space from the Application Support/Slack folder without fully uninstalling, navigate inside it and look for a storage subfolder or folders named after workspace IDs you no longer belong to. Each old workspace can leave a stale LevelDB directory behind. Removing a stale workspace folder will not affect workspaces you are still actively using.
Reducing Slack's Memory Usage on macOS
Clearing disk cache does not lower RAM consumption — those are two separate problems. Here are the most effective ways to reduce how much RAM Slack consumes at runtime:
- Limit the number of open workspaces. Each workspace runs its own renderer process. Sign out of workspaces you only check occasionally; you can always sign back in.
- Disable sidebar previews and animations. In Slack go to Preferences > Accessibility and turn off Animation. Reducing visual complexity lowers GPU memory pressure.
- Enable the "reduce motion" system setting. In System Settings > Accessibility > Display, enable Reduce Motion. This affects all Electron apps, not just Slack.
- Restart Slack once a day. Memory usage climbs over long sessions because Electron's garbage collector is not always aggressive. A daily restart resets the process tree.
- Keep macOS updated. macOS Sequoia and Tahoe include improvements to memory compression and the unified memory architecture on Apple Silicon. An up-to-date system handles Electron's footprint better than older releases.
Slack Versus Other Communication Apps: A Memory Perspective
It is worth understanding that this is not unique to Slack. Microsoft Teams (also Electron-based until its recent WebView2 migration on Windows — but still Electron on macOS), Discord, and Notion share the same architectural pattern. If you are curious how much storage all of your communication apps are consuming together, this guide on finding what is taking up space on your Mac explains how to audit every significant folder. A tool like Crumb can audit all of these locations at once and show you what is safe to remove before anything is deleted.
Should You Fully Uninstall and Reinstall Slack?
A full reinstall is the nuclear option: it removes everything in Application Support/Slack, which means all local workspace caches are wiped and must be rebuilt from the server. This recovers the most disk space — sometimes 4–8 GB — but Slack will feel slow for a few minutes after you log back in while it repopulates.
If you decide to go this route, dragging Slack.app to the Trash only removes the app binary. The support data and caches remain in ~/Library until you delete them manually. For a thorough walkthrough of removing all app remnants, see how to completely uninstall apps on Mac.
After reinstalling, sign in to only the workspaces you actively use. Each additional workspace multiplies the storage and memory cost, so keeping your workspace count lean is the single highest-leverage habit you can build.
Keeping Slack Lean Long-Term
Cache clearing is not a one-time fix — Slack regenerates its caches continuously. A reasonable maintenance rhythm is to clear ~/Library/Caches/com.tinyspeck.slackmacgap every two to three months. You can also set a reminder to check the size of ~/Library/Application Support/Slack and remove stale workspace folders whenever you leave a workspace. Most users find that this keeps Slack's disk footprint under 2 GB indefinitely, versus the 6–10 GB it can reach if left unattended for a year or more.