Como dizer "Campos de preenchimento obrigatório" em inglês

Good evening, zumstein

I agree entirely to you.
We have a bunch of options we can combine with the words required or demanded , like:

Required information / information required
Required data / data required
Required fields
Required blanks

Other synomys could be: vital (hospitals and clinics); obligatory; needed (basic forms).

You should read the following article:
ajuda-para-preencher-formulario-em-ingles-t36416.html

Best regards,

Ricardo.

(1) como-dizer-preencher-lacunas-em-ingles-t39953.html
(2) FROHMANN, Bernd. Revisiting "what is a document?", Journal of Documentation. 2009.
(3) Cambridge Online Dictionary.

Sometimes you have to fill in all the particulars of yours into the required fields of an online (or otherwise) form.

Examples from the web:
EBay indicates their required fields with * and includes a legend at the top “* Indicates required field”.

Yahoo puts “(Optional)” beside the only field on their sign up form that is optional (out of 18 fields). This means the form doesn’t get cluttered with asterisks.

Pra terminar, mais dois:
- Mandatory fields
- Compulsory fields

Não obrigatórios:
- Optional fields
- Voluntary fields

Já deu.