Where each kind of monitoring stops looking.
We compare categories, not named products. Each one watches part of the path from "visitor clicks submit" to "lead lands in the inbox". Only one watches all of it.
The honest verdicts
Uptime monitoring: keep it, it's just not enough
Uptime tools are cheap, mature, and good at their one job: telling you the server responded. Keep one running. But every silent form failure happens on a page that loads fine, so uptime alone leaves your lead pipeline unwatched.
Submission-only form checks: one step short
Tools that submit a test entry and confirm the form accepted it cover real ground: broken markup, failed validation, server errors. Then they stop, one step short of the inbox, which is where SMTP failures, spam filtering, and delivery drops actually eat the leads. "The form accepted it" and "the client received it" are different claims.
Manual testing: accurate, unscalable, and always late
Filling the form yourself is the most faithful test there is, and completely unworkable at portfolio scale. Ninety sites times three forms times once a week is a part-time job, done at whatever moment you remember, which is usually after something already broke. Automation exists because "I tested it last month" is not monitoring.
Watch the whole path, not the first step.
Delivery-verified monitoring on the free plan: 2 sites, 20 forms, no card.