Polyletter

How I Build Polyletter and Why

I had the problem that I searched every day for guests on talkshows from yesterday, because I can't watch them live and if it's interesting I want to watch on demand. So I searched for a system to deliver me a daily mail with the guests of the talkshows. I found nothing that fit my simple use case, so I built it myself.

What Polyletter actually is

With that basic idea, I thought of more than just talkshow guests. Wouldn't it be cool if you could choose what you'd like to receive in your daily Polyletter? Actually a custom newsletter but also more than that. A modular newsletter with topics which are more than just news and marketing.

Right now, topics range from daily stock picks and Trump news to Markus Lanz guests, YouTube recommendations, and even fun Polymarket bets. Maybe the global approach is a bit bold, but I automate some easy Polys with web search, API calls and AI.

Why I'm building it

I'm a solo founder based in Leipzig, Germany, and this is the kind of product I wanted to exist. I kept subscribing to newsletters that started great and slowly drifted into things I didn't care about. The problem isn't newsletters — it's that they're one-size-fits-all.

The AI part isn't a gimmick here. It's what makes the whole thing possible. A human editorial team creating personalized daily briefings for every user? That doesn't scale. But an AI pipeline that researches, writes, and compiles content for each subscriber's exact selection? That works.

The stack

Next.js (App Router, TypeScript)
Supabase for the database and auth
Resend for email delivery
Gemini for automation and translation
Vercel for hosting

Lesson from the first weeks

Admin tooling matters more than you think. I built an admin dashboard early, and it's saved me countless hours. Being able to preview content, test mails and manage everything from one place makes development sustainable. It's also the content hub, where I can see when the next Polyletter goes out and what's in it, to double-check the quality.

What's next

The platform is live at polyletter.com. Right now I'm focused on expanding the topic library — especially for the global market — and growing the user base through Reddit, Product Hunt, and Indie Hackers. I'm also exploring Telegram as an additional delivery channel alongside email.

This is devblog #1. I'll keep writing these as I build, sharing the technical decisions, the mistakes, and everything in between. If you're interested in following along — or if you just want a newsletter that actually respects your attention — come check it out.