Create Tags Filter in Shopify Store – No App

1. Create new snippet 'onsale-filter' and paste below code:

<style>
  .custom-sales-toggle {
    margin-bottom: 20px;
  }
  .custom-sales-toggle a {
    font-size: 12px;
  }
  .custom-sales-toggle a.turn-on {
    background: aqua;
    padding: 5px;
    border-radius: 5px;
  }
  .custom-sales-toggle a.turn-off {
    background: black;
    color: white;
    padding: 5px;
    border-radius: 5px;
  }
</style>
{% assign filtertag = 'onsale' %}

<div class="custom-sales-toggle">
  <a class="turn-on" href="{{ saleurl }}/{{ filtertag }}?sort_by={{ filtertag }}">On Sale</a>
  <a class="turn-off" href="{{ saleurl }}">Off Sale</a>
</div> 

{% render 'onsale-filter', saleurl: results_url %}