When comparing these two products, the main differences that stand out are plan limits, feature offering, and overall design philosophy.
A SlapForm "Sumo" plan costs $16/month with 2000 monthly submissions. Compare that to Submit JSON's $15/month plan with a submission limit of 10,000. Submit JSON's hobby plan at $5 has more submissions than that!
Regardless, it's another Formspree clone. SlapForm's HTML-first approach is misguided, where the cons far outweigh the pros.
In comparison, Submit JSON's API-first approach is more versitile, secure, and aligned with modern web development best practices.
Which is the best form backend for you? We think the answer is obvious, but we'll let you decide.