Using JavaScript on client stores, create a new list-collections template - https://www.shopify.com/partners/blog/28500611-using-javascript-to-super-power-your-clients-shopify-site

using-javascript-on-client-stores-new-list-collections-template.js

{% layout none %}
{% paginate collections by 50 %}

{
  "collections": [{% for collection in collections %}
    {
    {% if collection.image %}"image": "{{ collection.image }}",{% endif %}
    "body_html": "{{ collection.description | url_escape }}",
    "handle": "{{ collection.handle }}",
    "id": {{ collection.id }},
    "sort_order": "{{ collection.default_sort_by }}",
    "template_suffix": "{{ collection.template_suffix }}",
    "title": "{{ collection.title }}",
    "products_count": {{ collection.products_count }},
    "url": "{{ collection.url }}",
    "products": []
    }{% unless forloop.last %},{% endunless %}{% endfor %}
  ]
}
{% endpaginate %}