Grammarly Keyboard represents a significant advancement in mobile writing assistance by embedding AI-powered editing capabilities directly into iOS's native keyboard system. The application eliminates the need for copy-paste workflows by functioning across all installed apps, from email clients to messaging platforms and document editors. This system-level integration distinguishes it from web-based grammar checkers that require manual text transfer. The core functionality centers on real-time text analysis with multiple suggestion categories. Spelling and grammar corrections operate with high accuracy, identifying subject-verb agreement issues, misplaced modifiers, and common punctuation errors. Beyond basic corrections, the application provides conciseness recommendations that identify wordy phrases and redundant expressions. Vocabulary enhancement suggestions offer alternative word choices to improve lexical variety, while clarity algorithms restructure complex sentences for improved readability. The premium version includes tone detection that analyzes emotional undertones and empathy indicators in communications. User experience demonstrates thoughtful design with a clean interface that maintains iOS aesthetic principles. The keyboard activates through standard iOS keyboard switching and displays subtle underline indicators for potential issues. Tapping underlined text reveals detailed explanations and alternative phrasing options. Performance remains responsive during continuous typing, with minimal latency in suggestion generation. The application maintains user privacy by processing most data locally, though some advanced features require cloud processing according to the developer's privacy policy. User feedback trends consistently highlight professional communication benefits. Carolyn&Bentley (2025-08-15) appreciates the functionality while noting subscription affordability concerns, stating payment plan flexibility would improve accessibility. January 2017 (2025-08-13) emphasizes the tone-checking feature's value in maintaining appropriate professional demeanor. Multiple reviewers including Vadyer (2025-08-16) confirm effectiveness for business correspondence, though Yankeecub1 (2025-08-13) questions the pricing structure relative to AI feature implementation. The application demonstrates strongest performance in professional email composition and formal document drafting scenarios. Limitations include occasional false positives in complex sentence structures and dependency on subscription for advanced features. Network connectivity requirements for certain premium features may impact users in low-bandwidth environments. The tool proves most valuable for non-native English speakers, business professionals, and academic users requiring consistent writing quality across multiple communication channels.