Slack offers Free Trial, but Formspree does not.
Slack is designed for Freelancers, Large Enterprises, Medium Business and Small Business.
Formspree is designed for Individuals, Large Enterprises, Medium Business and Small Business.
Pricing for Slack Starts at $2.67/Month whereas for Formspree Starts at $8/Month when Billed Yearly.
Some top alternatives to Slack includes Microsoft Teams, Glip, Google Chat, ChatWork, Dialog, Office Chat, imBee, Takle, SPACE Channel and Teamwork Chat.
Some top alternatives to Formspree includes Cognito Forms, Formsite, Typeform, 123FormBuilder, stepFORM, HeyForm, Forms, Forms.io by 500apps, Getform, Makeforms, FormLink and SmartForms.