<form class="was-validated">
  <!-- valid input -->
  <input type="text" class="form-control is-valid" value="" required>
  <div class="valid-feedback">Looks good!</div>

  <!-- invalid input -->
  <input type="text" class="form-control is-invalid" value="" required>
  <div class="invalid-feedback">Field is required</div>

  <!-- valid tooltip -->
  <div class="position-relative">
    <div class="valid-tooltip">Looks good!</div>
  </div>
  
  <!-- invalid tooltip -->
  <div class="position-relative">
    <div class="invalid-tooltip">Field is required</div>
  </div>
</form>