Form validation is the process of checking that user-submitted data meets expected format, type, and content requirements before the submission is processed or stored.
Form validation ensures that the data users submit is correct, complete, and safe to process. Without validation, forms accept anything — empty fields, malformed email addresses, SQL injection attempts, or absurdly long strings that could break your system.
Validation happens at two levels. Client-side validation runs in the browser before the form is submitted, providing instant feedback. HTML5 attributes like required, type="email", minlength, and pattern handle common cases natively. JavaScript validation adds custom rules and better error messages.
Server-side validation runs after the form is submitted, on the server that receives the data. This is the critical layer — client-side validation can be bypassed by disabling JavaScript or submitting directly to the endpoint. Server-side validation ensures data integrity regardless of how the submission arrives.
Best practice is to implement both: client-side validation for user experience (fast feedback, reduced unnecessary submissions) and server-side validation for security and data integrity (never trust client input). FormsList handles server-side validation automatically, checking for required fields, valid email formats, and malicious content.
Validate that an email field contains a valid email address format (user@domain.tld) before accepting the submission.
Reject submissions where required fields like name, email, or message are empty. Show inline error messages pointing to the missing fields.
Enforce minimum and maximum character lengths — for example, requiring messages to be at least 10 characters and no more than 5,000.
Set up your form backend in under a minute. No server required, no complex configuration — just a simple endpoint for your forms.