FunBlocks AI

Proofly: Private AI Proofreading That Runs 100% on Your Device

Private AI proofreading that runs 100% on your device

Published: 12/6/2025

Proofly is a free, open-source Chrome extension designed to provide robust AI-powered proofreading capabilities entirely on your device. It aims to offer industry-class spelling, grammar, and punctuation correction without compromising user privacy by sending data to the cloud. Leveraging Chrome's built-in on-device AI (specifically Gemini Nano), Proofly underlines issues as you type, providing real-time feedback and corrections directly within your browser.

This innovative tool is ideal for anyone who values privacy while seeking to enhance their writing. This includes professionals handling sensitive documents, students, legal practitioners, or even casual users who want to keep their personal communications private. Proofly's core value proposition lies in its commitment to data privacy, offline functionality, and a lightweight, non-invasive user experience.

Problem & Solution

The proliferation of AI proofreading tools has been a boon for writers, but often comes at the cost of privacy. Many popular services require users to send their text to external servers for processing, raising concerns about data security and confidentiality, especially for sensitive information. This has created a dilemma for users who need advanced writing assistance but are wary of third-party access to their private communications, documents, and intellectual property.

Proofly directly addresses this critical privacy concern by performing all AI processing locally on the user's device. By utilizing Chrome's built-in AI capabilities, it eliminates the need to transmit any text data to the cloud, ensuring that sensitive information never leaves the user's machine. This approach fills a significant market gap for privacy-conscious individuals and organizations who previously had limited options for secure, AI-powered writing assistance.

Key Features & Highlights

Proofly boasts several compelling features that set it apart in the crowded field of proofreading tools:

  • 100% On-Device & Private AI: The most significant highlight is its complete on-device operation. No data is sent to external servers, ensuring maximum privacy and security for your writing. This means no accounts, no tracking, and verifiable open-source code for transparency.
  • Offline Functionality: After the initial model download, Proofly works completely offline, making it a reliable tool even without an internet connection.
  • Real-time Corrections: The extension underlines spelling, grammar, and punctuation issues as you type, offering instant suggestions to improve your writing.
  • Lightweight & Non-Invasive UI: Proofly is designed with a minimal footprint, integrating seamlessly into web pages without cluttering the user interface or slowing down browsing. It uses native web technologies like Web Components and Shadow DOM to ensure it "floats" on top of the host site without altering its structure.
  • Comprehensive Correction: It addresses a range of writing issues, including capitalization, missing words, and preposition usage.
  • Customizable Experience: Users can toggle specific correction types, adjust color coding for different error types, and choose between real-time checking or on-demand execution. A dedicated sidebar allows for reviewing and batch-processing issues.
  • Open-Source: Being open-source allows for community scrutiny and contributions, further bolstering trust and transparency regarding its privacy claims.

Potential Drawbacks & Areas for Improvement

While Proofly offers a compelling privacy-first approach, there are a few areas that could be considered for future enhancement:

  • Reliance on Chrome's AI: The performance of Proofly is inherently tied to the capabilities of Chrome's built-in AI (Gemini Nano). While this ensures privacy, its accuracy and comprehensiveness might evolve with Chrome's AI development. Users might wonder how its "industry-class proofreading" compares directly to established cloud-based solutions in terms of nuanced stylistic suggestions or advanced linguistic analysis.
  • Language Support: The description focuses on English proofreading. Expanding support for multiple languages, similar to some cloud-based alternatives, would significantly broaden its appeal to a global user base.
  • Advanced Writing Feedback: While it excels at core grammar and spelling, it could explore offering more advanced writing insights such as tone analysis, clarity suggestions, or conciseness recommendations, which are often found in premium cloud-based tools.
  • Integration beyond Chrome: While a Chrome extension serves a large user base, expanding to other browsers or offering desktop applications could cater to a wider audience and different workflows.

Bottom Line & Recommendation

Proofly is an exceptionally valuable tool for anyone prioritizing privacy in their digital communication and writing. Its commitment to 100% on-device processing, offline functionality, and open-source nature makes it a standout choice for sensitive work or personal use. If you're wary of sending your text to third-party servers but still desire robust AI proofreading, Proofly is a must-try. It offers a refreshing and secure alternative to mainstream grammar checkers, proving that powerful AI assistance doesn't have to come at the expense of your data privacy.

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