Building in Public: Adsloty, a Newsletter Ad Marketplace
Source: Dev.to
I’m building Adsloty. Here’s why.
If you run a newsletter, you’ve probably dealt with this: a brand reaches out wanting to sponsor an issue. Cool. Then starts the back‑and‑forth—pricing negotiations over email, figuring out dates, chasing invoices, copy‑pasting ad copy into your template manually. It works, but barely.
And if you’re on the other side (sponsor), a brand trying to get in front of a newsletter audience, it’s just as painful. You’re DMing creators, waiting days for replies, comparing pricing across spreadsheets, and hoping the audience actually fits your product.
I kept seeing this friction and thought: there has to be a better way.
So I started building Adsloty.
What it is
Adsloty is a self‑service marketplace where newsletter writers list their ad slots and sponsors book them directly. No emails back and forth. No awkward pricing conversations. Writers set their price, sponsors browse and book, and the platform handles payments and payouts.
Think of it like Calendly meets Gumroad, but specifically for newsletter ads.
The part I’m most excited about: when a sponsor submits an ad, it gets analyzed by AI before the writer even sees it. It scores how well the ad fits the newsletter’s audience, checks the tone, rates the clarity of the copy, and gives the writer an estimated click range. So instead of guessing whether an ad is a good fit, you get actual data to help you decide.
Why I’m building it
Honestly? Because I wanted it to exist.
The newsletter space is booming. More people are starting newsletters, more brands want to reach those audiences, but the infrastructure to connect them is still mostly manual. Existing tools are either too enterprise (built for massive publishers) or too scrappy (a Typeform and a Stripe link).
I wanted something in the middle—something a solo newsletter creator could set up in minutes, embed on their site, and start earning from without hiring a sales team or building a media kit.
And I wanted to build it myself. Not because I have to, but because I genuinely enjoy solving this kind of problem end‑to‑end.
The tech stack
Backend
- Language & framework: Rust with Axum
- Database: PostgreSQL, using SQLx for compile‑time checked queries
- Auth: JWT with refresh‑token rotation, Argon2 for password hashing
- Error tracking: Sentry
Frontend
- Framework: Next.js (App Router) with React 19
- Styling: Tailwind CSS
- State management: Zustand (global state) & TanStack Query (server state)
- Forms & validation: React Hook Form + Zod
Payments
- Stripe Checkout Sessions for sponsors
- Stripe Connect for paying out writers
- Platform takes a 10 % fee per booking (waived for the first three months of beta)
AI scoring
- Google’s Gemini API processes submitted ad copy together with newsletter audience data
- Returns a structured analysis: fit score, tone, clarity, estimated clicks, and recommendations
Media & observability
- Cloudinary for image hosting
- Sentry for error tracking (frontend & backend)
Infrastructure & DevOps
- Containerization with Docker
- Deployment on a Kubernetes cluster
- ConfigMaps & Secrets for settings
- Services & Ingress for networking
- Rate limiting with Governor
- Observability, health checks, scaling, and rolling updates
The aim is to treat this as a production system, not just an application.
I’m going to keep building in public. I’ll share what’s working, what’s breaking, the decisions I’m making, and why—no curated “everything is great” version.
If you’re running a newsletter and want to try it out when it launches, or if you’re a brand looking for a better way to sponsor newsletters, I’d love to hear from you.
More soon.