A simple light weight captcha guard to guard the bots. For details, you can read this article: https://blog.devgenius.io/simplecaptchaguard-add-captcha-protection-to-your-rails-forms-in-seconds-785413d3b807 But, in short, the usage is as below:

A simple CAPTCHA gem for Rails to prevent bots from submitting forms. And the usage is also so simple.

• ImageMagick needs to be installed in your system

Just add captcha_tag in your form. It will show you a captcha. Here is a simple code example:

  <%= captcha_tag %></br>Enter captcha : 
  <%= text_field_tag :captcha_input %></br></br>

and then add verify_captcha(params[:captcha_input]) in your controller. Here is a sample code example:

  # POST /inquiries or /inquiries.json
  def create
    @inquiry = Inquiry.new(inquiry_params)
    if verify_captcha(params[:captcha_input])
      respond_to do |format|
        if @inquiry.save
          format.html { redirect_to @inquiry, notice: "Inquiry was successfully created." }
          format.json { render :show, status: :created, location: @inquiry }
        else
          format.html { render :new, status: :unprocessable_entity }
          format.json { render json: @inquiry.errors, status: :unprocessable_entity }
        end
      end
    else
        flash[:alert] = "CAPTCHA failed. Please try again."
        redirect_to new_inquiry_path
    end
  end

Above is a very simple code example. You can use javascript and configure your route and add a method in your controller to implement the feature of try another captcha

If you don't want user to lose the data that they already entered into the form, you can implement the captcha before showing the form or handle the captcha failure in a different way, like using ajax.