Slack is where professional reputation is built in distributed teams - and most people send first drafts. The problem is structural: Slack desktop on Mac is an Electron app, which means macOS autocorrect does not work inside it. Unless you add a tool, you are writing with no correction net, and every typo is seen by colleagues the moment you press Return.
Why doesn't autocorrect work in Slack desktop?
Slack desktop is built with Electron - a framework that wraps web technology in a desktop-style shell. macOS autocorrect operates at the native app level and cannot reach inside Electron's text fields. This is not a bug or an oversight. It is a fundamental architectural limitation of how Electron apps work on macOS.
Grammarly handles it differently. Its browser extension only covers Slack in a browser tab, but the Grammarly for Mac app lists Slack among its supported desktop apps. It underlines problems and waits for you to accept each fix, which is a lot of clicking in a fast conversation, and your messages are checked on Grammarly's servers.
The only tool that reaches Slack desktop is one that works through the macOS Accessibility API - which is exactly how Charm operates. Charm reads and writes to text fields through the operating system's accessibility layer, which works regardless of whether the app is native, Electron, or browser-based.
How do you set up Charm for Slack?
Step 1: Install Charm and grant Accessibility permission. Charm needs Accessibility access to reach text fields in any app. When you first install Charm, it will prompt you to grant this permission in System Settings > Privacy and Security > Accessibility. Once granted, Charm works in Slack immediately with no per-app configuration required.
Step 2: Confirm Spells and Polish are enabled for Slack. Open Charm's preferences and check the per-app settings. Spells (spelling correction, cyan glow) and Polish (grammar correction at sentence boundaries, blue glow) should both be active for Slack. You can disable individual features per app if you want a different behavior in Slack vs. other apps.
Step 3: Use Oracle for common Slack phrases. Oracle (Charm's word prediction feature, purple glow, accept with Tab) learns patterns from your writing. In Slack, common phrases like "sounds good", "I'll take a look", "on it" and "let me check" become predictable quickly. Enabling Oracle in Slack reduces the keystrokes needed for the high-frequency responses that make up most Slack communication.
Step 4: Learn the Slack line break shortcut. This is essential to avoid sending incomplete messages: Shift+Enter adds a new line inside a Slack message. Plain Enter sends it. If your Slack settings are configured to send on Enter (the default), you will have sent partially-written messages at some point. Knowing the distinction prevents this and allows you to write multi-line messages without rushing.
Step 5: Reread the first sentence of important messages. In busy Slack channels, most people read the first line of a message before deciding whether to engage further. If the first sentence is unclear, grammatically messy, or buried in context, the rest of the message may not get read. With Charm running, grammar and spelling are handled - the first sentence habit is about structure and clarity.
Step 6: Use threads for complex messages. A single long message in a channel creates friction for other readers and is hard to respond to specifically. For anything longer than a few sentences, post a concise summary in the channel and use a thread for detail. This is a writing quality improvement independent of any correction tool.
The combination of Charm correcting a message before you send it and these structural habits produces significantly cleaner Slack communication without slowing down the speed that makes Slack effective.
Frequently asked questions
How do I get spell check in Slack on Mac?
Slack runs on Electron, so macOS autocorrect does not work inside it. Charm reaches Slack through the macOS Accessibility layer and corrects it the same way it corrects any other app: automatically as you type. Install Charm, grant Accessibility permission, and Spells and Polish work in Slack immediately with no additional configuration.
Does Grammarly work in Slack desktop?
Yes, with the Grammarly Mac app, which lists Slack among the desktop apps it supports. The browser extension alone only works in Slack's web version. Either way, Grammarly suggests fixes for you to accept and checks your text on its servers. Charm corrects your Slack messages automatically as you type.
How do I improve my Slack writing?
The most impactful changes: install Charm so messages are corrected as you type, learn Shift+Enter for line breaks (Enter sends), reread the first sentence before sending important messages, and use threads for complex topics rather than long channel messages.
Why doesn't autocorrect work in Slack?
Slack desktop is built with Electron, a framework that wraps web technology in a desktop shell. macOS autocorrect operates at the native app level and cannot reach inside Electron text fields. This is an architectural limitation, not a Slack setting that can be changed.
What is the best grammar tool for Slack?
Charm is the best grammar tool for Slack desktop on Mac. It corrects spelling and grammar as you type directly inside the Slack desktop app, on your Mac. Grammarly's Mac app also supports Slack, but it shows suggestions for you to accept rather than fixing as you type.