Compose.ai (YC W21) – AI-powered extension to speed up email writing

Hey HN! Michael here—founder of Compose AI (https://www.compose.ai) (also joined by my co-founder Wilson). Compose AI is a free Chrome extension that cuts your writing time by up to 40% with AI-powered autocompletion, rephrasing, and full-length email generation. It works across ~30 websites, so besides email, you can use it to do things like write Notion documents or chat on Slack (browser only (for now)).

I was in Mexico typing my 10th reply to a mundane email when it hit me: people shouldn’t be typing every letter of every word — especially not the same things over and over again. That got me thinking about building a tool that helps people type faster anywhere online and ultimately save them time—something that was easier said than done. It was quite challenging to balance the speed needed for real-time predictions with the model complexity needed for high quality predictions. Also, it was surprisingly challenging to integrate with a ton of different websites – I learned that there are many, many different ways to implement a “text box,” and experienced first hand, the joys of integrating with things like shadow dom and iframes.

I have been thinking about how to communicate with computers since I was in maybe 6th grade when I would literally dream about it. I remember I had a notebook in which I tried to analyze the linguistic structure of English to teach my computer English (not a great approach in retrospect). Later on, I worked in ML and AI at IARPA, Amazon, Disney, and BCG before starting an ML consulting firm. The trends in NLP finally caught up to my dream (LLM, distillation, fine-tuning, transformers, GPUs), so working on Compose AI seemed like the next logical step.

We are working to create a more holistic, AI-first writing solution. For now, our chrome extension has autocompletion, rephrasing (shorten, lengthen, change mood), and full email/reply generation functionalities. As you’re typing, the text is streamed to our backend servers, where we have relatively large transformers models that are tuned for specific scenarios.

If you need help with long-form content or the creative process, our web app (https://web.compose.ai) can generate product descriptions, blog outlines, sales pitches and more. Note: our web app asks for credit card on sign-up but includes a free 7-day trial.

For our Chrome Extension, we make money using a freemium subscription model. Your data is end-to-end encrypted and encrypted at rest. We will never sell your data and will only use it to fulfill your completions or improve your results.

Here are a couple demo videos of the extension generating responses to a Hacker News email:

https://www.loom.com/share/c36ec67b0a3a466aaa2ec5ee2399cb15

https://www.loom.com/share/44cf0f5893094d1191143b9f6fe11a5d

Thanks for reading! Would love to have some conversation with folks in the comments section below. Please share any feedback/ideas/experience!

Here are our open jobs: https://at.compose.ai/jointheteam

You can download Compose AI from the Chrome web store: https://at.compose.ai/download