In the modern digital landscape, an email that seems overly flawless can backfire. With applications like ChatGPT and Gemini simplifying the generation of well-structured messages, accuracy is no longer a dependable indicator of skill or authenticity. Instead, it might imply minimal effort and total dependence on AI.
Consequently, communication standards are evolving in unexpected ways. Minor errors—typos, informal language, or even all-lowercase formatting—are being understood as evidence that a genuine person crafted the email.
What once indicated carelessness is now viewed in some contexts as authenticity and even authority. The principles of ‘good writing’ in personal communication seem to be undergoing a significant transformation.
This evolving perspective has inspired the creation of tools aimed at reintroducing imperfections into otherwise flawless text. One example is Sinceerly, a Chrome extension developed by Ben Horwitz. This plugin intentionally alters emails by inserting errors and stylistic quirks, enhancing their human-like appearance.
In a post on X, Horwitz stated, “I made the anti-Grammarly. Mess up your emails with AI.”
I made the anti-Grammarly. Mess up your emails with AI. pic.twitter.com/1AF5qrCFwT
— Ben Horwitz (@horwitzben) April 23, 2026
How does it work?
Sinceerly functions through three modes. The ‘Subtle’ option removes filler words and introduces contractions, often including a minor typo early in the message. The ‘Human’ mode enhances the conversational tone while still incorporating imperfections.
The most distinctive setting, ‘CEO,’ produces very brief, lowercase emails, sometimes appending “sent from my iPhone,” imitating the fast, minimal communication style often associated with top executives.
Sinceerly was created as a ‘fun’ experiment, says Ben Horwitz
Horwitz, who developed the tool using Claude, mentions that the idea sprang from his personal experiences. Identifying as a slow typist and mildly dyslexic, he recalls spending considerable time early in his career ensuring that his emails were error-free.
We can add this line. Ben Horwitz, an investment partner at venture capital firm Dorm Room Fund, created Sinceerly, according to the website.
“I am a terrible typist, naturally, and lightly dyslexic. It would take me so long in my first job straight out of college to write emails and make sure there were no typos and everything. When Grammarly came around, it was like, ‘Oh, OK, this is pretty good for me.’ But now my email inbox is filled with AI slop,” says Horwitz, who is about to graduate from Harvard Business School.
He asserts that Sinceerly was intended as a ‘fun’ experiment rather than a serious commercial venture. While the plugin charges a small fee after limited free use, Horwitz has indicated that his primary interest lies in exploring and critiquing business culture.
Sinceerly provides limited free usage, allowing users to rewrite up to three emails directly within Gmail. For those choosing the paid version at $4.99 per month, the tool offers unlimited rewrites, swift switching between various modes, and a caching feature that enables users to access previously generated results instantly.
“I love creating products that make people think twice about technology. And in this case, it’s also somewhat a backlash against how we’re utilizing technology today. So, you know, there’s a $4.99 a month model that if you prefer not to bring your own key, you can pay me. I think it’s probably a small percentage of people who are paying and not using their own key, but it could be a business,” he told TBPN.
Here is how to activate it:Install from Web Store: Visit the Chrome Web Store, search for ‘Sincerely,’ and select Add to Chrome.
Locate Extension: Click the Extensions icon in the top-right corner of Chrome.
Pin: Find ‘Sincerely’ and click the pin icon to make it visible in the toolbar for quick access.
Manage Permissions: If prompted, allow the extension to read and modify data on websites.
Toggle Activation: If the extension is not functioning, go to the Chrome extension and toggle the switch to the ‘On’ position.
