How to Enable Autocorrect in Slack on Mac

macOS autocorrect does not work in the Slack desktop app on Mac. This is not a settings problem - it is a structural one. Slack is built with Electron, a cross-platform framework that bypasses macOS's native spell-checking API entirely. The best solution is Charm, which corrects spelling and grammar in Slack in real time using a different system API that Electron cannot block.

Why doesn't macOS autocorrect work in Slack on Mac?

Most Mac apps use Apple's NSSpellChecker API - the system framework that powers autocorrect in Mail, Notes, Pages, and thousands of other apps. When you enable autocorrect in macOS System Settings, it activates NSSpellChecker across all apps that support it.

Slack's desktop app is built with Electron, a framework that wraps a web-based interface inside a browser shell. Electron does not integrate with NSSpellChecker. This means macOS's autocorrect system has no channel into Slack desktop - it simply cannot reach the text fields where you type.

This is a known architectural limitation affecting all Electron apps, including VS Code, Notion, Discord, and others. It is not a bug and it cannot be fixed in Slack's settings. Approximately 40% of popular productivity apps on Mac are Electron-based, which means this gap affects a significant portion of daily typing for most users.

You may see red squiggles under misspelled words in Slack - those come from Slack's own built-in spell checker, not from macOS. But Slack's spell checker highlights errors; it does not auto-correct them.

Solution 1: Use Charm for real-time autocorrect in Slack (recommended)

Charm is a native macOS app that provides real-time spelling correction, grammar correction, and word prediction across every app on your Mac - including Electron apps like Slack. It works because it uses the macOS Accessibility API rather than NSSpellChecker. The Accessibility API operates at a different layer of the system and is not blocked by Electron.

To set up Charm in Slack:

1. Download Charm from theodorehq.com/charm and install it.
2. Open Charm and follow the setup prompt to grant Accessibility permission in System Settings. This one-time step is required for Charm to read and correct text in any app.
3. Open Slack and start typing. Charm begins correcting spelling immediately - no restart required, no per-app configuration.

Charm's Spells feature handles real-time spelling correction. The Polish feature adds grammar correction on top. Both run entirely on-device, so your Slack messages are never sent anywhere - a meaningful advantage for teams handling confidential communications.

Solution 2: Enable Slack's built-in spell check (highlights only)

Slack ships with its own spell checker that is separate from macOS. It will underline misspelled words in red to alert you to errors. This is better than nothing, but it is not autocorrect - you still have to right-click each underlined word and select the correct spelling manually.

To enable Slack's built-in spell check:

1. Open Slack and go to Preferences (Cmd + ,).
2. Select Accessibility from the sidebar.
3. Scroll to the Spell Check section and enable Check spelling.

This is worth enabling even if you use Charm, as the red underlines give you a visual signal for any words Charm may not have caught. But on its own, Slack spell check requires manual correction for every single error - which defeats the purpose of autocorrect.

Solution 3: Use Slack in a browser instead

Slack's web interface at slack.com runs inside Safari, Chrome, or Firefox rather than inside an Electron shell. Browser-based web apps do engage macOS's spell-checking layer more directly than Electron apps do, so you may get basic spell check suggestions when using Slack in a browser.

The tradeoffs are significant. Browser Slack lacks native keyboard shortcuts, push notifications behave differently, the sidebar cannot be configured the same way, and you lose integration with macOS features like Focus mode and the notification centre. Most users who switch back to the desktop app quickly. For occasional use this can work, but it is not a practical long-term replacement for the desktop app.

Comparison: your options for autocorrect in Slack on Mac

Charm is the only option that provides genuine real-time autocorrect in the Slack desktop app on Mac. It also extends the same correction to every other app on your Mac simultaneously - so you get autocorrect in Mail, Notes, VS Code, and anywhere else you type, all from a single $9.99 one-time purchase. For more on how Charm compares to macOS's built-in tools, see Charm vs macOS Autocorrect.

Frequently asked questions

Why doesn't autocorrect work in Slack on Mac?

The Slack desktop app is built with Electron, a cross-platform framework that does not use macOS's native NSSpellChecker API. This means macOS built-in autocorrect is blocked at the system level and will never fire inside Slack desktop, regardless of your macOS settings.

How do I get autocorrect working in Slack on Mac?

Install Charm from theodorehq.com/charm. Charm uses the macOS Accessibility API rather than NSSpellChecker, which means it works inside Electron apps like Slack. Grant Accessibility permission once and Charm corrects spelling and grammar in real time across all your Mac apps, including Slack.

Does Slack have its own spell check on Mac?

Yes, but it only highlights misspelled words with a red underline - it does not auto-correct them. To enable it, open Slack Preferences, go to the Accessibility section, and tick Check Spelling. You still have to right-click and choose a correction manually.

Does using Slack in a browser give better spell check on Mac?

To some extent. Slack in Safari or Chrome does engage macOS spell checking more effectively than the desktop app. However, it only shows suggestions - it does not auto-correct as you type. You also lose native features like keyboard shortcuts and notification centre integration.

Is Charm safe to use with Slack?

Yes. Charm processes all corrections entirely on-device. Your text never leaves your Mac, which is especially important in Slack where you may be sending confidential work messages. No account is required and there is no cloud connection.