Ask HN: What's the simplest way to store email collected from a landing page?

There are MANY ways to do it. You can use firebase and GCP functions. I run Control Plane and on our platform it would cost you $1.45 per month with a really fun development experience. Simply create a Docker image in any language. It can write to any DB. Dynamo would probably cost you nothing and in case you need to have a LOT of records, it would still cost near nothing. You probably want to use ReCaptcha in silent mode to avoid bots. If you want to try it out, or have me show you how to easily build this, shoot me a note to doron@controlplane.com and I'm happy to show you. Our website is at https://controlplane.com. All that said, I am sure there are even easier ways to do this, including Google docs, etc. The good thing about Control Plane is that you can write any code and have it be highly available and low latency no matter where callers are. An overkill for your use case, but you can start at near free and scale as you need to.

Embed a signup form from Mailchimp or any of a dozen competitors. https://mailchimp.com/help/add-a-signup-form-to-your-website... works fine with Mailchimp's free plan, supports custom fields, and can be embedded in static HTML.

Host the static website on netlify/vercel/cloudflare pages with a formspree.io form.

You get an email whenever the form is submitted.

I have the setup running on my personal website. Easiest way without hosting or spinning up server.

Self-hosted PgSQL?

Or even SQLite maybe but concurrent writes might become an issue if you get lots of traffic...