Validations

The platform applies automatic validations to protect your endpoints and keep incoming data consistent.

Automatic validations

Each submission goes through the following checks before it is processed:

HTTP method — Only POST submissions are accepted. Any other method will be rejected with a 405 Method Not Allowed error.

Content-Type — The submission must use one of the supported formats: multipart/form-data, application/x-www-form-urlencoded, or application/json. Unsupported formats will be rejected.

Active endpoint — The service checks that the form_id in the URL belongs to an existing and active form in your account. If the form has been deleted or disabled, the submission will be rejected.

Submission limit — If your account has exceeded the monthly submission limit for the current plan, new submissions will be rejected until the cycle resets or you upgrade your plan.

Field validations

The tool does not enforce field-level validation by default — that responsibility stays in your HTML form or frontend JavaScript.

To validate fields in the frontend, you can use native HTML attributes:

<form action="https://simpleapiform.com/f/{form_id}" method="POST">
  <input type="text" name="name" required>
  <input type="email" name="email" required>
  <input type="text" name="message" minlength="10" required>
  <button type="submit">Send</button>
</form>

Response codes

Code	Meaning
200 OK	Submission received and processed successfully
400 Bad Request	The payload format is invalid
404 Not Found	The endpoint does not exist or has been deleted
405 Method Not Allowed	A method other than POST was used
429 Too Many Requests	The plan submission limit was exceeded