Compare Grammarly and Merlin AI: Which Extension is the Best?
| Key Features A summary of the most important features offered by each extension. |
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| Our Rating Tooltivity's expert review score for each extension, based on hands-on testing and research. | 8.8 Winner in this category | 8.4 |
| Total users Total active users across all major browsers: Chrome, Edge, Firefox, and Safari. | 54,562,704 Winner in this category | 1,000,000 |
| Total ratings Total number of user ratings received across all supported browsers. | 47,134 Winner in this category | 8,802 |
| Average rating Average user rating across all browsers, calculated from available store ratings. | 4.2 ⭐ | 4.8 ⭐ Winner in this category |
| Entry Level Price The minimum price required to start using the extension. "Free" means a free tier is available. | Free | Free |
| Chrome User rating and stats for the extension on Chrome browser. |  4.5 3.75 Average Chrome Web Store rating from the last 100 reviews 39.0M+Users | 4.8 3.24 Average Chrome Web Store rating from the last 100 reviews 1.0M+Users Winner in this category |
| Edge User rating and stats for the extension on Edge browser. |  3.9 3.69 Average Microsoft Edge Store rating from the last 100 reviews 14.9M+Users Winner in this category | - |
| Firefox User rating and stats for the extension on Firefox browser. |  4.1 4.15 Average Mozilla Firefox Add-ons Store rating from the last 100 reviews 657.8K+Users Winner in this category | - |
| Safari User rating and stats for the extension on Safari browser. | - | - |
| Features Tooltivity's expert score for the 'Features' aspect of each extension. | 9.5 Grammarly goes beyond basic grammar and spelling checks. It offers advanced features like tone detection, vocabulary enhancement, and generative AI capabilities. Compared to competitors, Grammarly provides a more comprehensive set of tools, making it a valuable asset for any writer. Winner in this category | 8.0 Merlin AI offers a variety of features including summarizing, writing, coding, diagramming and more. It supports multiple AI models such as GPT-4, Claude and Gemini and allows users to create custom AI chatbots and knowledge bases. The platform also integrates with the web and files in real time. However, some features, such as PDF summarization, are not as robust as those of specialized tools. It also lacks what we consider to be the important function of direct communication between AI and the current website. In addition, the function of direct communication between AI and the current website, which we consider important, is missing.  |
| Performance Tooltivity's expert score for the 'Performance' aspect of each extension. | 9.0 Grammarly performs well across different platforms, providing real-time suggestions without significant lag. The tool is reliable and helps improve writing efficiency. Winner in this category | 7.5 Merlin is generally fast and responsive, but it can slow down browsers, especially on older hardware. There are occasional bugs and crashes, though the team releases frequent updates and improvements. |
| Design Tooltivity's expert score for the 'Design' aspect of each extension. | 8.5 The design is clean and intuitive, making it easy to navigate. The color-coded underlines for suggestions are helpful, and the interface is user-friendly. However, some users might find the pop-ups slightly intrusive. | 9.1 The design has a modern look and feel, with handy keyboard shortcuts and sidebar integration that make navigation easier. That said, the user interface can feel cluttered and overwhelming, especially for new users, and there are inconsistencies between the extension, web, and mobile versions.  Winner in this category |
| Value for Money Tooltivity's expert score for the 'Value for Money' aspect of each extension. | 8.5 While Grammarly offers a free version, the Premium plan is relatively expensive. However, the advanced features and comprehensive feedback justify the cost for those who need a robust writing assistant. Grammarly is the priciest option for a reason—because, in our view, it's the best writing tool available in its category. If you're looking for the best writing assistant, go for the Premium plan, you won't regret it! Winner in this category | 8.2 The free plan is generous for light users, offering a substantial daily quota and access to a wide range of basic features. The Pro plan is competitively priced, especially when compared to the cost of subscribing to multiple separate AI tools, and unlocks unlimited access to all models and advanced features. However, the absence of a free trial for premium features means users must commit before experiencing the full capabilities of Merlin AI. Additionally, some users report that the query system—where different models and features consume varying amounts of daily queries—can be confusing or feel restrictive, particularly for those trying to understand how far their usage will go on each plan. |
| Ease of Use Tooltivity's expert score for the 'Ease of Use' aspect of each extension. | 9.0 Grammarly is straightforward to use, with a minimal learning curve. The browser extension integrates seamlessly with various platforms like Google Docs and Gmail, allowing you to get started right away. Winner in this category | 8.5 Getting started with Merlin AI is straightforward—installation is quick, and the onboarding process is simple enough for most users to begin using core features right away. However, the platform’s extensive feature set can be overwhelming at first, leading to a noticeable learning curve as users explore everything it offers. Some users have expressed confusion about how the daily query limits work, how different models are selected or switched, and which features are available on each plan. Occasional bugs and log-in issues can also disrupt the workflow, requiring users to troubleshoot or reach out to support. Overall, while Merlin AI is accessible, mastering its full capabilities may take some time and patience, especially for those new to AI tools. |
| Security & Privacy Tooltivity's expert score for the 'Security & Privacy' aspect of each extension. | 8.0 Grammarly takes privacy seriously, with stringent security measures in place. While an account is required, the company assures users that their data is not sold or made public. However, some users may still have concerns about data processing. | 9.3 Merlin does not sell user data to third parties and only uses data for core functionality. The privacy policy is transparent, but some users remain concerned about the amount of data collected and the permissions required. Winner in this category |
| Conclusion A summary of our findings and final thoughts for each extension. | In our eyes, Grammarly is the best choice for anyone who wants to write professional articles or other things in English. Even though Grammarly has an expensice price tag, you can't get anything better on the market. We have been using Grammarly for a long time now. And even in the world of ChatGPT and other AI tools, Grammarly is just super handy and helpful. For us, the Premium plan is worth every penny. This only applies as long as you are in the English-speaking world. If you need other languages, we would recommend LanguageTool instead. | Merlin AI is a powerful and versatile tool that can really boost the productivity of a wide range of users. The integration of multiple AI models and functions into a single extension is ideal for this p However, Merlin is not completely perfect. We encountered occasional bugs, inconsistencies in the user interface and some performance issues. Pricing can also be confusing, and some features are locked behind a paywall.. Overall, Merlin AI is a good choice for anyone looking for an all-in-one AI assistant for the browser - especially if you value having multiple AI models and tools in one place. |
| Our Recommendation | In our comparison between Grammarly and Merlin AI, Grammarly came out on top, scoring 8.8. Grammarly is the most widely used, with over 55 million users and 47k+ reviews—and it also delivered the strongest performance in our tests. User reviews for Grammarly reflect our findings, while we rate Merlin AI lower than users do. Notably, Merlin AI has the highest user rating in the Chrome Web Store at 4.80, which is even higher than our rating of 8.4. In the end, the differences between these extensions are minimal, so your choice may come down to personal preference or specific features.
If you want a quick recommendation, Grammarly is our top pick. But as always, the best choice depends on what matters most to you. | |
