Ben Horwitz, a Harvard Business School student, has developed a Chrome browser extension called Sincerly (also reported as Sinceerly) that modifies AI-generated email text to introduce typos and informal language. The goal is to make the text appear more human-written.
Plugin Functionality
The plugin utilizes Anthropic's Claude AI and offers three distinct modification modes:
- Subtle mode: Removes filler words and adds contractions, typically introducing a typo in the first sentence.
- Human mode: Adds a more conversational tone, also including a typo in the first sentence.
- CEO mode: Rewrites text in all lowercase, increases brevity, and may add a "sent from my iPhone" signature.
Pricing and Development
Horwitz created the plugin using Anthropic's Claude AI, citing his own typing difficulties and the observation that grammatically perfect emails are now widely perceived as AI-generated. He views the project as a form of social commentary rather than a primary income source.
The service is free for a limited number of initial uses, after which it costs a one-time fee of $4.99 for continued access.
Reported Usage
Horwitz reported observing a user workflow in which individuals generate text using AI, paste it into an email, and then use Sincerly to add imperfections. He described this pattern as part of a "communication arms race," noting that many emails he received appeared similar due to widespread AI generation.
"This is part of a communication arms race," Horwitz said.
Key Takeaway
The plugin reflects a growing cultural shift where perfectly polished writing is now seen as a telltale sign of AI use—prompting a demand for tools that reintroduce human flaws.