Copy Keplars?

Build me a Developer Tools web app like Keplars.

Keplars does: Email Infrastructure for Modern Product Teams, Keplars powers transactional and marketing emails with full delivery visibility, sandbox testing, and seamless scale - with strong developer experience,  It reportedly makes about $828/mo, so the core idea clearly has demand — I want a lean version I can run and charge for.

Start from the open-source project ixartz/SaaS-Boilerplate (https://github.com/ixartz/SaaS-Boilerplate) — reuse what fits, strip its branding, and build the specifics below on top of it.

Requirements:
- Nail the single core loop that Keplars is known for — build that end to end first.
- The main dashboard/workspace where users do the primary task, with sensible empty states.
- Any AI step that makes it feel modern (generate, summarize, or automate the tedious part).
- Data persistence, search/filter, and a clean history/list view.

Also:
- Clean, modern, responsive UI with a thoughtful landing page.
- Email/password auth and a simple paid tier (Stripe test mode) so it's ready to charge.
- A README covering setup, environment variables, and how to deploy.

Ship a working MVP I can run locally first, then help me deploy it.