Productivity comparison
Grammarly vs Slack Ai
Business writing, grammar, tone, and communication quality across apps · Team conversation summaries, channel catch-up, and workplace knowledge retrieval
| Decision point | Grammarly | Slack AI |
|---|---|---|
| Best for | Business writing, grammar, tone, and communication quality across apps | Team conversation summaries, channel catch-up, and workplace knowledge retrieval |
| Category | Productivity | Productivity |
| Price | Free + paid plans | Paid add-on / plan availability varies |
| AIToolsEssentials score | 4.4/5 | 4.1/5 |
Evidence status
Free: $0/month and 100 generative-AI prompts per month. Pro: displayed at $12 USD and includes 2,000 AI prompts per member per month, unlimited personalized suggestions, full-sentence rewrites, tone controls, plagiarism checking, and AI-generated-text detection. Enterprise: contact sales and includes unlimited prompts per member per month plus enterprise controls. The extracted pricing page did not unambiguously expose the billing cadence attached to the displayed $12 Pro amount.
Official sources checked 2026-08-25Open verification questions
- The billing cadence represented by the $12 Pro price was not rendered unambiguously in the retrieved official pricing text.
- Grammarly's exact treatment may differ for negotiated Enterprise agreements, which are governed by a separate Customer Business Agreement rather than the public self-service terms.
Official sources confirm AI drafting, rewriting, tone adjustment, fluency suggestions, grammar assistance, plagiarism checking, and AI-text detection. For Free, Premium, and single-user Pro accounts, Product Improvement and Training is enabled by default, but users can opt out; when disabled, user content is not used for model training, validation, or product improvement. Multi-user accounts bought directly online are also enabled by default, with an administrator opt-out. Enterprise-tier, sales-purchased Pro/Business, and Education accounts have training disabled by default. Grammarly says its external LLM service providers may receive prompts and context to provide generative features but may not train their models on user content. Under the October 29, 2025 Superhuman terms, inputs and outputs are User Content, and users own all right, title, and interest in User Content; the terms also grant Superhuman a broad license for operating, improving, customizing, and developing its services.
Free: $0. Pro: $7.25/user/month when paid annually or $8.75 when paid monthly. Business+: $15/user/month annually or $18 monthly. Enterprise+ uses sales-based pricing. The pricing page labels Free and Pro as including Basic AI and Business+ as including Advanced AI; the exact feature set depends on plan and admin settings. The page was also displaying a 50%-off-for-three-months promotion for eligible Pro and Business+ purchases.
Official sources checked 2026-08-25Open verification questions
- Slack's AI Principles page says AI features are included in paid plans, while the current pricing page labels the Free plan as having Basic AI. The exact production availability and limits of Free-plan AI could not be reconciled from the official pages.
- Slack does not publish a single numeric usage allowance for all AI features; some capabilities state that plan limits apply.
- No explicit, AI-output-specific ownership statement was located in the checked official Slack sources.
Official pages list capabilities including Slackbot, conversation and thread summaries, daily recaps, AI search, file summaries, workflow generation, huddle notes, translation, and enterprise search, with availability varying by plan. Slack states that Customer Data never leaves Slack-controlled infrastructure and is never used to train LLMs. Third-party LLMs are hosted within Slack's cloud environment; providers do not have access to Customer Data. AI only uses content the requesting member is authorized to access. Conversation summaries and search answers are ephemeral; recaps are stored for 90 days. Workflow-generated summaries stored in messages or canvases follow the organization's retention settings. Admins can disable or restrict native AI features.
How to decide
Match each platform to your actual workflow constraints. Run one real workflow in each finalist before paying.
Quick recommendation
Use the trial checklist on each review page and the free scorecard to record time-to-result, corrections needed, and monthly cost at your expected volume before committing to a plan.