I was creating a site, that has a product page with a small three-field form:

  • name
  • email
  • phone

To send the form, user shouldn’t be registered.

They say, it’s better to start with something, so my first intention was to make form to remember all entered fields (even if the user hasn’t submitted the form – she won’t need to type if she decides to send it later).

Then I understood that on public computer it can expose some personal info to another person, like phone.

So is it a bad idea in general to save fields in the forms? Are there any fields that are “safe” to save? Or is it better not to save any fields, but leverage autocomplete feature?

  • 3
    After they complete the form, asked if they would like to create an account with that information. If so you are free to remember it. If not forget the information.
    – bishop
    Jan 11, 2018 at 15:51

3 Answers 3


...on [a] public computer it can expose some personal info to another person...

You hit the nail on the head with that concern. It's alright to reserve the feature of remembering data for your signed-in users. There's no way to tell whether or not you're actually helping your users or exposing them.

The browser auto-fill feature actually prompts users if they would like to save the data they entered. If you just rely on this feature, then the user can decide at this point if they would like it to be auto-filled next time.


I assume this is a web form served via browser, yes?

For a simple one-time sent form I can't really see why anyone would ever need the information to be saved unless the sign up also functions as the login (given there's no password, I assume that doesn't apply). When in doubt, just disable the autocomplete if you value privacy over smooth re-entry. And in this case there seems to be no re-entry anyway.

Also do note that I'm not aware of any modern browser that saves autocomplete information unless you actually submit the form, so failing to complete the form wouldn't save any info anyway, unless you're talking some implementation you roll your own (you should generally not replicate browser features unless extremely necessary).

If the field is extremely private, like, say, credit card info or SSN, then I would say Autocomplete should be off entirely (though browsers have taken to requiring the security code when autocompleting credit cards).

Regarding public computers, I'm not sure this is a particularly useful case to worry about unless you have an unusual case where this is extremely common. Browser autocomplete asks people if they want to save sign-ins anyway and I would hope most libraries/etc simply link directly to the in-private versions of browsers these days. This is more something for the user and computer provider to worry about than it is for you unless, as above, it's ridiculously secure information you shouldn't save in any context.

  • Yep, the form is served by browser and I’m utilizing JavaScript to save the values when the user clicks [×] in the browser window. Then on the next page load it populates the form values with JavaScript again.
    – Runnick
    Jan 11, 2018 at 14:45

There are two types of forms - private and public. Private fields are the ones located in user's profile page, account settings page, etc. Public - contact forms, sign in or sign up forms.

No public forms should remember any data that could affect user's privacy or security.

Private forms can contain all data that should be in those forms, apart from user's password.

When it comes to deciding what information should be remembered, just put user's privacy and security first.


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