Lightfern for Email
The telepathic AI writing tool
193 followers
The telepathic AI writing tool
193 followers
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.
Lightfern for Email
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 :)
@dougli Congrats on the launch! What’s the first moment users realize it’s truly ‘telepathic’?
Lightfern for Email
@kimberly_ross Thansk! Usually it's the moment they first reply to an email thread. There's many things we can do to shorten the gap to the "aha" moment, but that's where it is right now :)
@dougli Congrats on the Gmail rollout! Curious to see how users adapt to writing with full context like this. Definitely feels like a big shift in daily communication. Also curious, what’s been the most surprising feedback since the Gmail launch?
Lightfern for Email
Thank you @kotishree ! Honestly, people want this in many different places (Slack, Superhuman, Hubspot, etc.) and we can't build the integrations fast enough. If you'd like this somewhere let us know!
@dougli congrats on the launch! Do you plan to add voice as input?
Lightfern for Email
@austin_heaton Thanks! That's a highly requested feature. Short term we're focusing on getting this working across more platforms (Outlook, LinkedIn, Slack, etc), but long term it's definitely on the roadmap!
Visla
@dougli very impressive!
Lightfern for Email
@mogabr Thank you Gabe! We worked super hard on it!
Lightfern for Email
@mogabr @dougli It was also super fun to build :) have to thank the awesome team for that.
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?
Lightfern for Email
Raycast
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.
Here's what I love about this: the QWERTY keyboard was designed to slow down MECHANICAL TYPISTS.
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.
Lightfern for Email
@chrismessina We're delighted to have you as our Hunter!
One clarification on data processing -- we do process remotely (big GPUs needed to power the models), but we never store your data or train on it without consent.
Here's to telepathic communication :)
Meet-Ting
@chrismessina @dougli One of the most exciting launches on PH!
Raycast
@dougli @dbul you guys should work together! :)
Meet-Ting
@dougli @chrismessina Funnily enough, we're meeting tomorrow!
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?
Lightfern for Email
@valeriia_kuna Thanks Anna for the kind words! I agree - personalisation is important.
We have mechanisms to balance past thread context with the user’s global writing style. Both approaches are valid; what matters is having the most accurate, up-to-date version of the user’s style and feeding it to the AI at the right time. Context engineering is central to our product, and we’re focused on making it correct and reliable for our users.
Can't wait to see what you've been working on 👀 Fingers crossed for your product!
@gastlich Thanks for the insights, Jacek! (It’s Valeria, by the way, but no worries :) ). I love the term context engineering—it really captures the complexity of what we are all trying to achieve with personalization right now!
Fingers crossed for Lightfern's growth! Looking forward to seeing how you guys evolve this further!
Lightfern for Email
@valeriia_kuna Sorry Valeriia for the mistake. It won't happen again :)
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.
Lightfern for Email
@marie_brayer_ftw
"It is so good that I'm starting to use Gmail as a lightweight notetaker" hahaha I do this too! We're working on getting this working in other places, can't wait to release new features for you to try.
Thank you for being such an early tester! We couldn't have done this without you :)
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.
Lightfern for Email
@kevan_williams Thanks Kevan! Really appreciate the feedback.
Lightfern for Email
@kevan_williams Thank you - really appreciate that. Authenticity is exactly the hard part we cared most about. We’re trying to build something that supports how people already communicate, rather than replacing it with a “better” but generic version. Feedback like this genuinely means a lot to us 🙏
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!
Lightfern for Email
@linh_s Thanks for helping us test out Lightfern! Really appreciate all the feedback