Mailharness

Test inboxes for the mail your app sends at signup — verification email, OTP codes and magic links. Your test asks for an address, drives the app, and waits for the message.

Create a project.

No invite, no card, no email to confirm. The project exists and the key works by the time this button stops spinning.

Project name

Lowercase letters, digits and hyphens. It is a DNS label, so it will be lowercased.

What you get, and what you do not

Immediately: A project, its own subdomain, and an API key. Every address under that subdomain receives, whether or not you created it.
A ceiling: This is a trial tier: a monthly cap on messages received and an hourly cap on new addresses. Both numbers are issued with your key and shown on the next screen, before you have built anything on them.
To lift it: Redeem an invite against the same project — no card, effective immediately, and it works on every instance. Whether you can also subscribe depends on whether this instance has a payment provider configured; the next screen says which, from the signup response. Either way the slug, the addresses and the key all stay as they are — there is nothing to migrate.

Why there is a ceiling at all: Mailharness receives mail for everybody at one domain, and apps block domains that look disposable. The limits are on volume rather than on getting in, because a domain gets blocklisted by what a project does, not by how many projects exist.