Autocorrect on macOS Sequoia: What Changed and What Still Doesn't Work

macOS 15 Sequoia brought Apple Intelligence Writing Tools to Apple Silicon Macs - but the underlying system autocorrect barely changed. The same limitations that existed in Ventura and Sonoma remain: autocorrect still fails in Electron apps like Slack, VS Code, and Obsidian, still catches spelling better than grammar, and still has no per-app configuration. Apple Intelligence adds post-edit rewriting for supported apps. Real-time autocorrect in every app still requires a tool like Charm.

What did macOS Sequoia actually change about autocorrect?

The short answer: very little. The system autocorrect engine in Sequoia operates on the same underlying logic as it did in Ventura and Sonoma. Apple did not rebuild the NSSpellChecker API or fundamentally change how autocorrect identifies and replaces text.

What Apple improved in the Sequoia keyboard and text experience was largely around predictive text on iPhone and sentence-level completions in some text fields - improvements that were primarily iOS-focused. On Mac, the core autocorrect behavior is the same spell-and-replace engine it has been for years.

macOS Sequoia adoption reached approximately 45% of Mac users within six months of release, making it the fastest-adopted macOS version in years. Most users who upgraded expecting improved writing tools found the same autocorrect they had before - with a new Apple Intelligence badge that only works on specific hardware.

What did Apple Intelligence add - and what it doesn't cover?

Apple Intelligence Writing Tools are the genuinely new feature in Sequoia. They allow you to select text in a supported app and invoke rewriting operations: Proofread (corrects grammar and spelling in the selection), Rewrite (suggests alternative phrasings), Make Friendly/Professional/Concise (adjusts tone).

This is meaningfully useful in the apps where it works. For Apple Notes, Pages, Mail, and other native Apple apps on Apple Silicon, the Proofread function provides competent post-edit correction.

The critical constraints:

• Requires Apple Silicon: Apple Intelligence is not available on Intel Macs, period. Approximately 35% of active Macs remain Intel-based. These users receive no Apple Intelligence benefit regardless of macOS version.
• Native Apple apps only: Apple Intelligence does not work in Electron apps. Slack, VS Code, Discord, Notion, Obsidian, Linear, and most third-party Mac apps are excluded.
• Post-edit only: Apple Intelligence requires you to select text and invoke the tool. It does not correct errors as you type. This is fundamentally different from real-time autocorrect.
• Not available mid-sentence: You cannot invoke Writing Tools on a partially typed sentence in a message compose box in the same way autocorrect fires automatically.

60% of active Macs are now Apple Silicon - but even on those machines, Apple Intelligence writing tools only cover a fraction of where professionals actually write.

What autocorrect limitations remain in Sequoia?

The structural limitations of macOS autocorrect are unchanged in Sequoia:

Electron apps are still excluded. Slack, VS Code, Discord, Notion, Obsidian, Linear, WhatsApp Desktop - none of these support NSSpellChecker, the API macOS autocorrect relies on. This is an architectural issue with Electron, not a macOS bug. It exists in Sequoia exactly as it did in Ventura. 73% of the top 100 Mac productivity apps are Electron-based.

No per-app configuration. Sequoia still does not let you set different autocorrect behavior per application. You cannot say "correct aggressively in Mail, but leave technical terms alone in VS Code." It is a global setting.

Proper nouns and technical terms still trigger false corrections. Autocorrect on Sequoia still over-corrects brand names, product names, and developer terminology. A programmer writing "useState" or "API" in a native text field will see familiar unwanted substitutions.

Grammar correction is still minimal. Real-time autocorrect in Sequoia catches spelling. Grammar correction - subject-verb agreement, missing articles, incorrect tense - still requires either Apple Intelligence (post-edit, Apple apps only) or Charm (real-time, every app).

The best autocorrect setup for macOS Sequoia in 2026

The optimal Sequoia writing setup layers tools rather than relying on any single one:

For native Apple apps (Mail, Notes, Pages, Messages): Apple Intelligence's Proofread feature is excellent for reviewing completed text before sending. It covers grammar and style issues that real-time correction misses.

For Electron apps (Slack, VS Code, Notion, Discord): Charm is the only real-time correction option. It uses the Accessibility API - which works at a different layer than NSSpellChecker - and corrects text in Electron apps that Apple Intelligence and macOS autocorrect cannot reach.

For real-time correction everywhere: Charm runs continuously in the background on macOS 14+ (including Sequoia) and provides correction in every app without requiring you to select text and invoke a tool.

Frequently asked questions

Did macOS Sequoia improve autocorrect?

Not significantly. Sequoia added Apple Intelligence Writing Tools - a post-edit rewriting feature for Apple Silicon Macs in native Apple apps. But the underlying real-time autocorrect engine is largely unchanged from Ventura and Sonoma. The same limitations including Electron app failures remain in Sequoia.

Does Apple Intelligence work in Sequoia on Intel?

No. Apple Intelligence requires both macOS 15 Sequoia AND an Apple Silicon chip (M1 or later). Intel Macs can run Sequoia but cannot use Apple Intelligence. Approximately 35% of active Macs are Intel-based and get no benefit from Apple Intelligence regardless of macOS version.

Does autocorrect work in Slack on macOS Sequoia?

No. Slack is an Electron app, and macOS autocorrect has never worked in Electron apps - including on Sequoia. This is unchanged in Sequoia. Charm uses the Accessibility API and corrects text in Slack on any macOS version including Sequoia.

What is the best autocorrect for macOS Sequoia?

Charm is the best autocorrect for Sequoia because it covers every app - including Electron apps like Slack, VS Code, and Notion that Apple Intelligence cannot reach. It provides real-time spelling and grammar correction and word prediction for $9.99 once, requiring macOS 14 or later.

Do I need Charm if I have Apple Intelligence?

Yes. Apple Intelligence Writing Tools work only in native Apple apps as a post-edit feature - you select text and invoke rewriting. Charm provides real-time correction as you type in every app including Electron apps where Apple Intelligence cannot function at all. They address different use cases and complement each other.