What filtering means and why you'd add it
Filtering lets visitors narrow down content on your site by selecting criteria — like showing only products under $50, or blog posts from a specific month. Instead of scrolling through everything, they see only what matches their choices. The filter updates the page without a full reload, making the experience faster and less frustrating.
Filtering is most useful when you have more than a dozen items in one place: a product catalog, a job board, a portfolio gallery, or a directory. Without it, visitors either leave or spend time hunting. With it, they find what they want in seconds.
You have three main routes: use a plugin or theme feature if your site runs WordPress or Shopify, build filtering with code if you control the backend, or use a third-party widget that handles it for you. Which one works depends on what platform you're on and how much control you want.
Key Takeaways
- WordPress sites can add filtering through plugins like FacetWP or Elementor's built-in filters without writing code.
- Shopify stores have filtering built into most themes, and you control it through the theme customizer and product tags.
- Custom-coded sites need filtering logic in the backend (PHP, Node.js, Python) paired with JavaScript on the front end to update results without reloading.
- Third-party widgets like Algolia or Klevu handle filtering for you but add a monthly cost and depend on an external service.
- The simplest filters use checkboxes or dropdown menus for one or two criteria; complex filters with price ranges and multiple options require more setup.
Using WordPress plugins for filtering
If your site runs WordPress, the easiest path is a plugin. FacetWP is the most popular choice for product and post filtering. You install it, assign which fields (like category, price, or custom fields) should be filterable, and it generates the filter widget automatically. It works with WooCommerce stores and custom post types.
Elementor, a page builder many WordPress sites use, includes filtering for posts and products built into its widgets. If you've already designed your page in Elementor, you can turn on filtering in the widget settings without installing anything extra. The filters appear as checkboxes or dropdowns next to your content.
Filters for Posts is a lighter option if you only need to filter blog posts or custom post types by category, tag, or author. It's free and requires almost no setup — just activate it and choose which post types to filter.
All three handle the technical work behind the scenes. You don't write code; you just tell the plugin which fields matter and where to show the filter.
Filtering in Shopify stores
Shopify themes come with filtering built in. When you add products to your store and tag them (like "blue", "small", "sale"), Shopify automatically lets customers filter by those tags on your collection pages. You don't install anything — it's already there.
To set it up, go to your Shopify admin, open a collection, and look for the "Filtering and sorting" section. You can choose which product properties (tags, type, vendor, price, or custom attributes) show as filter options. Shopify handles the rest: when a customer clicks a filter, the page updates to show only matching products.
If your theme doesn't show filtering options by default, check the theme's customizer. Most modern Shopify themes let you toggle filters on or off and rearrange them. If your theme is very old or custom-built, you may need a developer to add filtering code.
Building filtering with code
If you control your own backend — whether it's a custom PHP site, a Node.js app, or a Python Flask site — you can build filtering from scratch. The process has two parts: the backend logic that queries your database, and the front-end code that lets users choose filters and displays results.
Backend: Write a route or endpoint that accepts filter parameters in the URL or request body. For example, `/products?category=shoes&price_max=100` tells your server to fetch only products in the shoes category under $100. Your code queries the database with those conditions and returns matching results as JSON.
Frontend: Use HTML checkboxes, radio buttons, or dropdown menus for each filter. When a visitor clicks one, JavaScript sends a request to your backend endpoint, receives the filtered results, and updates the page without reloading. Libraries like Fetch API (built into modern browsers) or jQuery (if your site uses it) handle the request.
This route gives you full control but requires you to write and test the code. If you're not comfortable with backend languages, a plugin or third-party widget is faster.
Using third-party filtering services
Algolia and Klevu are search and filtering services that work on any platform. You send them your product or content data, they host the search and filtering logic, and you embed a widget on your site. When someone filters, the widget talks to their servers and shows results.
The advantage is speed and features: these services are built for filtering and search, so they're fast even with thousands of items. The disadvantage is cost — both charge monthly fees starting around $50 to $100 — and you depend on their service staying up.
These work best if you have a large catalog (thousands of items) and want advanced features like faceted search, typo tolerance, or AI-powered recommendations. For smaller sites, a plugin or built-in theme feature is usually enough.
Choosing between simple and complex filters
Simple filters use one or two criteria: category, status, or date. A few checkboxes or a dropdown menu is all you need. WordPress plugins and Shopify's built-in filtering handle this with no extra work.
Complex filters let visitors narrow by many criteria at once: price range, color, size, brand, and availability all on the same page. These need more code or a more powerful plugin. FacetWP and third-party services like Algolia are built for this.
Start simple. If your visitors ask for more filter options, add them. A page with five filter checkboxes is easier to use than one with twenty.
Common filtering setups and what they cost
| Setup | Best for | Cost | Effort |
|---|---|---|---|
| WordPress plugin (FacetWP) | WordPress sites with products or posts | $99–$299/year | Low — configure in admin |
| Elementor built-in filters | WordPress sites already using Elementor | Free (or part of Elementor Pro) | Low — toggle in widget settings |
| Shopify theme filters | Shopify stores | Free | Low — enable in theme customizer |
| Custom code (PHP, Node.js, Python) | Custom-built sites with full backend control | Free (developer time) | High — write and test code |
| Third-party service (Algolia, Klevu) | Large catalogs needing advanced search | $50–$500+/month | Medium — embed widget, sync data |
Frequently Asked Questions
Does filtering slow down my website?
Not if it's done right. Filtering that updates without reloading the page (called AJAX filtering) is fast. Third-party services like Algolia are built for speed. The main slowdown happens if your database query is inefficient or you're loading thousands of items at once. Test with your actual data to see.
Can I filter by price range with a slider?
Yes, but it requires more code than simple checkboxes. FacetWP includes price range sliders. If you're coding it yourself, you'll need a JavaScript library like noUiSlider or Ion.RangeSlider to handle the slider, plus backend code to filter by the min and max values.
What if I want to filter by multiple criteria at once?
All the methods mentioned here support it. When someone selects "blue" and "under $50", your filter logic applies both conditions at the same time. The more criteria you add, the more important it is to test that your filters work together correctly.
Can I filter content that's not products?
Yes. WordPress plugins like FacetWP work on any post type — blog posts, events, team members, portfolios. Shopify filtering is product-specific, but custom code works on anything. Third-party services vary; check their documentation.
How do I make filters work on mobile?
Most plugins and services handle this automatically — they detect screen size and adjust the filter layout. If you're coding it yourself, use CSS media queries to stack filters vertically on small screens or hide them behind a "Filter" button that expands when tapped.