What our apparel store learned about Stencil, the REST API, and the customizations that actually moved the numbers.
We launched our BigCommerce store in 2021 selling premium denim and basics to independent boutiques. After two years our conversion rate plateaued at 1.8%. Over the next 14 months, five specific customizations took us to 3.4%. Some we built in-house. Others we outsourced. Here is what worked, what we learned, and the rough impact each one had on our numbers.
I am going to lead with the data because that is what most merchants reading this care about. These are real numbers from our own Google Analytics 4 and BigCommerce Analytics, not made-up benchmarks.
| Metric | September 2024 baseline | October 2026 current |
|---|---|---|
| Conversion rate (sitewide) | 1.8% | 3.4% |
| Average order value | $147 | $182 |
| Cart abandonment rate | 71% | 58% |
| Mobile LCP (Largest Contentful Paint) | 3.8s | 1.9s |
| Lighthouse Performance score (mobile) | 47 | 89 |
The default Optimized One-Page Checkout works for most stores. Ours was not most stores. We have B2B accounts that need PO numbers, retail customers who want guest checkout, and a small wholesale program that requires net-30 terms. Three flows. One checkout page that needed to handle all of them.
We rebuilt the checkout using the BigCommerce Checkout SDK to override the default behavior. Our in-house developer spent about three weeks on it. The hardest part was the conditional payment options: net-30 customers should not see credit card fields by default, but should be able to opt in if they want. The full walkthrough of how the Checkout SDK actually works is in our deeper writeup if you want the technical breakdown.
Result: cart abandonment dropped from 71% to 64% sitewide. The B2B segment specifically went from 78% to 51%.
Our wholesale customers were buying through a manual process. They emailed a request, we built a custom quote, then we manually entered the order. It took 30 to 45 minutes per order on our side and was the bottleneck on growing the wholesale segment.
We switched to BigCommerce B2B Edition's Customer Groups feature paired with Price Lists. Price lists are assigned at the variant level and can be linked to a customer group, a sales channel, or a customer group on a specific channel. The setup itself was a few hours of admin work. The integration with our REST API v3-based dealer dashboard took longer because we wanted real-time tier updates, not nightly batch syncs. Our B2B pricing tier playbook covers the exact configuration we use.
Result: B2B reorder rate jumped from 31% to 47% within four months. Our team got the manual order entry time back.
The default Stencil category page filters worked but were slow on collections with 200 or more products. Filter changes caused full page reloads taking 2 to 4 seconds. Customers were dropping off mid-filter session.
We rebuilt the filtering with a custom Stencil component that calls the REST API for filtered results and updates the DOM in place. No page reload. The filter state stays sticky across navigation.
Result: category page bounce rate dropped from 47% to 28%. Pages-per-session went from 2.8 to 3.9.
This was the customization that produced the largest single conversion lift, and the one we tried hardest to do ourselves before admitting we needed help.
Our LCP on mobile was 3.8 seconds. The Cornerstone-derivative theme we started with was loading every script eagerly, the hero image was unoptimized, and we had three review widgets injecting DOM nodes synchronously. Lighthouse was telling us all of this. Fixing it was another matter.
We tried for two months. Changed image formats, lazy-loaded what we could, removed two of the review widgets. Got down to 3.1 seconds. Still failing Core Web Vitals. The remaining bottlenecks were architectural decisions baked into our theme that we did not understand well enough to safely change without breaking checkout.
After trying to handle it internally, we hired an agency that specializes in BigCommerce development services to do a proper performance rebuild. They restructured how the Stencil bundle loads, replaced the hero image system with responsive WebP via the BigCommerce image CDN, and moved the remaining review widget to lazy-load on intersection observer. Total project: 6 weeks.
LCP went from 3.1 to 1.9 seconds on mobile. Lighthouse Performance score went from 47 to 89. The conversion rate lift in the first month after launch was the largest single jump we have measured. Worth more than we paid for the work, by a lot.
We use a third-party logistics provider for fulfillment. Originally, orders were exported as a CSV every morning, uploaded to the 3PL portal manually, and tracking numbers came back into BigCommerce by 2 PM the following day. That is a 24-hour gap between the customer placing an order and seeing it acknowledged with a tracking number.
We set up BigCommerce Webhooks to fire on the store/order/created event, push the order to the 3PL's API in real time, and write back the tracking number on the store/shipment/created event. The whole integration took our developer about ten days.
Result: orders shipped same-day jumped from 41% to 89%. Customer service tickets asking "where is my tracking" dropped roughly 70%.
A few honest takeaways from these 14 months.
BigCommerce's customization surface is bigger than most merchants realize. The REST API v3 covers almost every store object you might want to manipulate. The Webhooks system is reliable. Page Builder and Script Manager handle most of what marketing teams ask for without engineering involvement at all.
Page speed is the customization that produces the biggest conversion lift but is the hardest to do well in-house. We tried for two months. The bottlenecks were architectural decisions baked into our theme that we did not understand well enough to safely change. A specialist team produced better results in 6 weeks than 2 months of internal effort.
Do the cheap customizations first. Custom checkout flows, B2B pricing groups, and webhook integrations all have ROI you can measure within a quarter. Page speed rebuilds and full theme rewrites have longer payback windows but bigger eventual impact.
For deeper context on what BigCommerce can and cannot do at the platform level, the official BigCommerce resources hub has been the documentation we lean on most. The Wikipedia entry on BigCommerce covers the platform's history if you are evaluating it for the first time.
We have plans for more in 2027. A custom B2B portal built on the Storefront API is at the top of the list. The platform keeps shipping new APIs faster than we can adopt them, which is a problem we are happy to have.