Finish thoughts before fingers hit keys. Working directly in your inbox as a browser extension, Lightfern nails the details that make emails feel like you - nicknames, sign-offs, your tone of voice - and pulls context from past threads to finish sentences the way you would. All with zero data retention by default.
I’m Doug - I was OpenAI’s first hire in London but left to co-found Lightfern.
The problem:
AI-driven communication isn’t authentic. You want to communicate clearly and thoughtfully.
But wording your thoughts is time-consuming.
Lightfern is the telepathic AI writing tool. We started with a simple idea: Cursor, but for email. Today, we’re rolling out public availability for Gmail users via our browser extension.
Finish thoughts before fingers hit keys. Lightfern nails the details that make emails feel like you - nicknames, sign-offs, your usual tone - and pulls context from past threads to finish your sentences the way you would.
Build stronger relationships. Lightfern keeps you thoughtful, whether it’s remembering your VC’s ski trip to Switzerland or a long-forgotten invoice number.
Redraft and edit without ever leaving the page. Chat with AI that already has full context.
All this with zero data retention by default.
Lightfern is the best autocomplete model in the world. Nothing else comes close in contextual awareness or speed.
Congrats on the launch! Positioning this as Cursor for email with deep thread context and personal tone is compelling. How does Lightfern balance pulling in rich historical context with avoiding overreach, especially so suggestions feel helpful and accurate without surfacing details that might no longer be relevant or appropriate in a given conversation?
Congrats on the launch. Authenticity in AI communication is a hard problem, and it’s refreshing to see it addressed head-on instead of optimizing for generic better writing.
Cursor for email analogy is perfect! I love the focus on personalisation, we are actually building a personalised product ourselves, so I'm a believer that personalisation is king in this space. How does Lightfern handle the balance between using past thread context and the user’s global writing style? Does it prioritize recent interactions, or does it build a long-term tone of voice profile?
Congrats on the launch! 🚀 Love this telepathic, in‑inbox email copilot with zero data retention.
Congrats on the launch @gastlich@mleelightfern@dougli 👏 I loved the idea of “Cursor for email,” especially the focus on personal tone and context. W
TLDR I used Lightfern since alpha, and it's reduced my inbox anxiety by 80%
LightFern makes writing in Gmail feel effortless and “safer,” especially when you write in multiple languages (English and French for me). The autocomplete is genuinely context-aware: it remembers subtle personal details (who someone is, what you called something last time, your weird turns of phrase) and can even fill in relationship context (e.g., “John… CEO of CompanyZ” popping in automatically). The multilingual handling is a standout—smooth switches between English, French, and frenglish, with far fewer awkward failures than most tools (French slightly less strong than English, but still very usable). You don’t even need to hit Tab constantly; the comfort of having a good suggestion sitting there is weirdly satisfying, and for non-native English (and if you’re a bit shy) full autocomplete reduces anxiety by helping you land the right phrasing faster. The strongest proof is behavioral: you actually use it daily, and you feel noticeably weaker when you’re accidentally logged out (“oops, let’s log in”).
It is so good that I'm starting to use Gmail as a lightweight notetaker because it supports continuous writing, not just post-hoc summaries.
Tried it out as an early release - the UX and general polish is great, and the team behind Lightfern are a really talented and focused group of people. I look forward to continuing to see Lightfern grow and flourish 🌱
I've been using Lightfern since its Beta and I just love the context it has on my calendar and previous e-mails.. and all these details pop up just at the right time!
Hey 👋 I'm Jacek, a Founding Engineer at Lightfern.
I've spent most of my career in startups, which is why I'm especially excited to be here - building and shipping things end to end with a small, focused team. I'm responsible for product delivery across the stack, so if you've got any questions (technical or not), I'm very happy to answer.
What I love about Lightfern is that it's always there when you're stuck - whether that's wording, simplifying an over-complicated sentence, or just getting unstuck.
So, please try it out and share your thoughts 🤗
Hello! Marcus here, co-founder at Lightfern.
Super excited to hear any and all feedback from everyone! We’re all very keen to build a product for you.
Happy to answer any questions on the technical aspects of Lightfern too. I love a good discussion!
I have been using it since early private beta. I tried any sort of email automation to auto draft, nothing truly saved me time like Lightfern. I love that it knows my style, but also gives me control to edit and rephrase.
Hey all,
I'm Matt, one of the co-founders of Lightfern
I spent years as a researcher in medtech, so privacy has always been at the heart of what I build. One of the reasons we have a zero data retention policy as default. Developing this model was technically challenging and super fun for me so I hope you like it!
We built Lightfern because we were tired of AI writing tools that are optimised for the mean. Lightfern actually learns your style - how you write, your rhythm, the way you talk.
Try it and let us know what you think!
Over the moon to have worked on this! As a former journalist, the power of high-quality, expressive writing cannot be understated.
In the past, I've had to navigate writing my novel outside of my life and work in tech. I'm grateful to now combine my two worlds alongside such a talented technical team.
Can't wait to see what the future of communication looks like next!
I've been using lightfern since it launched in beta. Doug, Matt and Marcus, its impressive what you've built. This is truly the closest to telepathy I've experienced. I love that it lives within gmail and doesn't add any noise to my tool stack. Its been a true productivity boost and makes replying to emails addictive 🚀
Lightfern for Email is probably the closest you're going to get to telepathy until Neuralink is out and available for general purpose use cases.
Therefore — until then, you really have to try Lightfern to get it.
Simply install the Chrome Extension, grant access to Gmail and Calendar (your data isn't stored unless you agree to it), and then go compose an email in Gmail or Outlook on the web and be amazed.
We're still suffering from that design — when we could shorten the distance between what we intend to communicate and what actually ends up on the screen.
And that's what Lightfern is all about: helping you express yourself authentically — telepathically! — so you can get across what you really mean with integrity and clarity.
Hey Product Hunt 👋
I’m Doug - I was OpenAI’s first hire in London but left to co-found Lightfern.
The problem:
AI-driven communication isn’t authentic.
You want to communicate clearly and thoughtfully.
But wording your thoughts is time-consuming.
Lightfern is the telepathic AI writing tool. We started with a simple idea: Cursor, but for email. Today, we’re rolling out public availability for Gmail users via our browser extension.
Finish thoughts before fingers hit keys. Lightfern nails the details that make emails feel like you - nicknames, sign-offs, your usual tone - and pulls context from past threads to finish your sentences the way you would.
Build stronger relationships. Lightfern keeps you thoughtful, whether it’s remembering your VC’s ski trip to Switzerland or a long-forgotten invoice number.
Redraft and edit without ever leaving the page. Chat with AI that already has full context.
All this with zero data retention by default.
Lightfern is the best autocomplete model in the world. Nothing else comes close in contextual awareness or speed.
🪴 Install now for unlimited free access during our beta: https://lightfern.com/.
We’ll be here all day to answer your questions and hear your thoughts, so please reach out and say hi :)