GPTCheck is a free Chrome extension developed by Useful Extensions. It falls under the category of Browsers and is classified as an Add-ons & Tools subcategory. This extension allows users to fact-check information generated by ChatGPT, a popular language model.

With GPTCheck, users can highlight any sentence and right-click to select the extension. The extension then searches through Google using the highlighted sentence and retrieves the top website results. It compares the highlighted sentence with the most similar sentence found in the search results using a cosine similarity score. The higher the score, the more similar the sentences are considered to be.

GPTCheck utilizes machine learning language models to convert sentences into numerical representations and calculates the correlation between the numbers to determine the similarity score. This feature enables users to verify information generated by ChatGPT and ensure its accuracy.