JotForm is a free online form builder which helps you create online forms without writing a single line of code. No sign-up required.
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I can see that you already reached the submission storage limit which is 500. The error refers to the number of Total Submissions Storage. It is not referring to the monthly submissions.
Under the Free plan, you only have 500 total submission storage. It means that you can only store up to 500 submissions in your account. You need to delete some submissions in order to free up your submission storage. Here's a guide: How-to-Delete-Form-Submission-Data
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