Field notes from building a WooCommerce checkout plugin. What the platform actually does, which filters genuinely work, and how to test the parts that hide behind an interaction.
Diagnosis
There are four gates between a visitor and an order, they fail for completely unrelated reasons, and almost every store is losing disproportionately at exactly one of them. How to measure all four this afternoon, with data you already have.
Conversion
The real ranked reasons shoppers abandon, what each one is worth, and the WooCommerce fix for it. The two highest value changes are a settings checkbox and a line of text on your product page.
Benchmarks
We read the sources and they disagree with each other by more than double. Why the published benchmarks conflict, what really moves your rate, and the baseline you should compare against instead.
Pricing
Shipping cost is the largest single reason people abandon. Whether you can afford to absorb it is arithmetic: the break-even calculation, setting a threshold from your own orders, and when it is the wrong answer.
Trust
A bigger reason for abandonment than a long checkout, and nobody has it on a to-do list. Trust is judged visually rather than technically, and the research on badges is more uncomfortable than you would like.
Measurement
Detecting a 10% lift at a 2% conversion rate takes about 154,000 sessions. The arithmetic that ends most small-store tests before they start, and the perfectly good method to use instead.
Checkout design
CSS, hooks, template overrides or a plugin. What each route can and cannot change, the hook map in the order it fires, and the version drift trap that breaks overrides silently three releases later.
Checkout fields
The working snippet, the four fields that are safe to remove, the four that will break your shipping and tax, and the reason the same code does nothing at all on a block checkout.
Checkout design
What Baymard's research actually concludes about multi-step versus one page, why most case studies comparing them are confounded, and the five mistakes that make a stepped checkout convert worse.
Mobile
Five specific, measurable failures: the button that is present but untappable, the sticky bar trapped by a transformed ancestor, horizontal overflow, the hidden total, and the wrong keyboard.
Revenue
The only offer on your store that interrupts a payment already in progress. Where it goes, what to put in it, the price ceiling, and the one metric that says whether it earned or cost you money.
Post purchase
The only page every paying customer sees, and on most stores it is a table and a total. What belongs on it, and the tracking mistake that quietly doubles your reported conversions.
Platform decisions
The classic checkout is not deprecated, whatever you have read. A decision guide with a compatibility checklist you can run against your own plugin list, plus the third option most articles never mention.
Comparison
CheckoutWC, Fluid Checkout, FunnelKit and OptiCheckout on real August 2026 pricing, site limits and feature caps. We make one of them, so every section names what the competitor does better.
OptiCheckout gives the classic WooCommerce checkout seven modern templates and a visual builder. No migration, no checkout conversion, and your existing extensions keep working.