ByHand is a Chrome extension designed to enhance email authenticity by certifying human authorship through typing cadence analysis. This tool operates within Gmail, monitoring the rhythm of your typing rather than the content of your emails. By capturing metrics such as pause durations and keystroke variability, it generates an authorship score that indicates whether an email was composed by a human or potentially generated by AI. When the score meets a certain threshold, a footer stamp is added to the email, which recipients can click to view a detailed report of the typing analysis.

The extension prioritizes user privacy, ensuring that no email content is transmitted or analyzed, and only timing statistics are recorded. ByHand’s features include live passive analysis, customizable stamp styles, and a unique report for each email sent. This tool is particularly beneficial for professionals who need to validate their email correspondence, such as journalists or consultants, and anyone looking to differentiate their personal writing from AI-generated text.