Custos - Personalized email drafts in seconds from your inbox

Hi Product Hunt 👋

I’m Khalil, one of the founders of Custos.

We built Custos because we were spending way too much time writing emails that should have taken seconds. Drafting, rewording, overthinking all added up to hours lost every week.

Custos helps you reply faster by automatically drafting emails in two ways: it pre-generates responses the moment an email hits your inbox and it instantly writes replies when you hit respond. You don’t need to change how you work. Custos works directly from your Gmail inbox through a Chrome extension and API combination. Your emails stay natural, contextual, and sound just like you.

If you’re curious, we’d love for you to give it a try and share any feedback, questions, or ideas. People from companies like dLocal, Tabby, Puzzle, Antler and Web Summit are already using Custos and helping us make it better every day.

Visit our website and try Custos for free at https://www.withcustos.com/

Does the data from the email somehow get processed by you/or seen?

We've built this product to be as simple and intuitive to use as possible. If you've tried using Gemini in your Gmail and you never used it again, our product is for you!

@khalil_osman1 @omar_mostafa4 @joaquincoitino @hamahmi_custos I just downloaded but have yet to start playing around with the tool.. that being said.. I think its a great niche solution! Like @busmark_w_nika mentioned - leading with what the security parameters are might be helpful for some on the fence users (I'd assume).

A few questions (that may have already been answered)

1. Is there a way to train the software on my email style / speaking style / give it access to a knowledge base on how I WANT to speak (vs how I've spoken in the past)... ex if its trained on or has access to lots of my emails (many of which are internal) - I speak/write much differently to my colleagues than to customers / prospects etc.

1.a. If there is - would there be a way to toggle on specific (agents / knowledge bases / speaking styles) depending on the demo of who the email is being sent to?

2. What LLM is this trained on and can I choose one that I like best (presume I like the email outputs from claude more than GPT5) or I am a deepseek loyalist etc.

Either way - killer product and congrats on the launch - looking forward to seeing how things unfold for your team!

We built something not to only save others, but ourselves in the first place. We know how much of a pain it is, so we decided to ease it up on everyone.

Compassion and determination is put into every single detail.

Hello everyone,

Communication can be a very emotional and special thing. Repetitive and transactional comms is not. At Custos, we want to automate the latter so you have more time for the former.

We are starting with email. Our product works where you already work: Gmail. No new interfaces, menus or shortcuts to learn.

As someone who writes a ton of emails and insists on replying to every single one, I knew there had to be a better way. And, true to the engineer spirit, if something takes 10 minutes to do but 10 hours to automate… I’ll always choose the automation. 😄 That’s what inspired me to help build Custos — it was both a fun challenge and a real solution to make my life (and hopefully yours) so much easier. Now, instead of spending endless hours drafting replies, I can focus on what really matters while Custos handles the heavy lifting. 🚀

We built Custos because we know the pain of staring at a blank email screen, trying to find the right words. With Custos, you can create context-aware, personalized drafts in just seconds—right inside your inbox.

Custos drafts over Gemini any day!

Ahhh I love this, exactly the sort of tool that makes my life instantly 10x easier when I'm doing my daily work!

Thanks to the team for this & best of luck w/ the launch!

I have been using this product for a month or so, I love this product.

Custos is super easy to set up and does a great job of capturing my writing style. Makes clearing my inbox a breeze. I like how fast and accurate it is - does a great job of capturing context even in complex threads. Had several “wow” moments with this product…highly recommend.

Looks awesome - like it should be native to Gmail... I was going to ask about security but @busmark_w_nika already asked :) Being CASA Tier 2 certified is pretty tough work and enough confidence that there's nothing nefarious going on :)

Great job team! Congrats on the launch!

Love Custos, one of those 10x tools and it sticks to my tone. Best of luck hope you keep scaling!

Custos creates email drafts that match my tone perfectly, cutting my response time in half. Great for busy professionals who want to work smarter!

Love Custos, fantastic product, output is super personalized and context aware. Recommend trying it out if you want to get more efficient with managing your inbox.

Congrats on your launch 🎉🎉

Amazing tool ❤️

Custos is great because it doesn’t force you to change your workflow, it just works within it. It replies to emails automatically, saves you time, and helps you organize your thoughts so you never start from scratch.