I tried to launch a SaaS to do automated QA of email sends (check them for broken links before sending, mis-sized images, etc.) which was a big failure as the p

I tried to launch a SaaS to do automated QA of email sends (check them for broken links before sending, mis-sized images, etc.) which was a big failure as the pain wasn't strong enough. But to try and promote it I created a free automated email subject line checker which people loved -> https://sendcheckit.com https://sendcheckit.com A couple years in and we've checked around 5 million subject lines for people. There's an embed API that I originally let people use for free, but after it started being really abused I now charge a small annual fee for access. It's not enough for a full time income and I don't really talk about the site that much as it doesn't fit in the "portfolio" of my other professional interests which are mostly cybersecurity related.