HTML has some nifty helpers for form validation. We can recommend using those on your frontend, to keep things simple.
Please see MDN for more info about that.
<form method="post" action="https://rake.red/{project}/{form}"> <label>name</label> <input type="text" name="name" required /> <label>email</label> <input type="email" name="email" required /> <button type="submit">Subscribe!</button> </form>
Server Side Validation
That being said, we take our responsibilities as well. User submitted data can't be trusted, and should always be validated!
All form submissions are validated using JSON Schema. You don't need to compose those schemas yourself. Instead, our schemas are self learning. As soon as your form starts generating data, fields are registered in the schema.
You'll find the schema in your form's setting page. There you can tighten the screws. Change data types, limit field lengths, and mark fields as required or optional.
Additional properties
Disallow additional properties when the schema is complete, and you want to restrict users to the known fields only.
