# Custom WooCommerce Extension Development

> Custom WooCommerce extension development compatible with HPOS and the block checkout: payment, pricing rules, shipping, B2B and connectors, on a fixed quote.

- Page: <https://www.datafirefly.com/en/expertise/woocommerce-extension-developer/>
- Language: en
- Last updated: 2026-09-24
- Other languages: [fr](https://www.datafirefly.com/expertise/developpeur-extension-woocommerce/index.md), [es](https://www.datafirefly.com/es/pericia/desarrollador-extensiones-woocommerce/index.md), [de](https://www.datafirefly.com/de/fachkompetenz/woocommerce-extension-entwickler/index.md), [it](https://www.datafirefly.com/it/competenze/sviluppatore-estensioni-woocommerce/index.md), [pl](https://www.datafirefly.com/pl/ekspertyza/programista-rozszerzen-woocommerce/index.md), [nl](https://www.datafirefly.com/nl/expertise/woocommerce-extensie-ontwikkelaar/index.md), [pt](https://www.datafirefly.com/pt/expertise/programador-extensoes-woocommerce/index.md)
- Index: <https://www.datafirefly.com/en/expertise/llms.txt>

WooCommerce has changed deeply in recent years: HPOS order storage enabled by default on new stores, a block-based checkout, the Store API for the cart. Many extensions written before these changes only half work: a field missing from the block checkout, a report reading the old orders table, a payment gateway absent from the new checkout. We build custom WooCommerce extensions written for today's WooCommerce, with a written scope and a fixed price agreed before we start.

We also publish our own WooCommerce extensions (dynamic pricing, pre-orders, quotes, accounting export, tiered loyalty…), maintained and documented. Every custom extension follows the same development rules as that catalogue.

## What we build on WooCommerce

### Checkout and payment

Extra checkout fields, validation rules, payment gateways specific to your bank or PSP, deposits and deferred payments. Each gateway is registered in both the classic checkout and the block checkout, so it stays available whatever the theme.

### Prices, promotions and sales rules

Prices per customer or group, quantity discounts, minimum orders, products reserved for certain accounts, prices calculated from dimensions or options. Calculations rely on WooCommerce totals hooks to stay consistent across cart, order, invoice and emails.

### Shipping and logistics

Custom shipping methods (volumetric weight, postcodes, time slots, local carrier), order export to a 3PL and tracking numbers imported back.

### B2B and subscriptions

Business accounts, EU VAT number validation, quotes converted into orders, invoicing on payment terms. For recurring billing we use WooCommerce Subscriptions when it covers the need, or a direct Stripe integration when more control is required. See also our page on [WooCommerce subscriptions](https://www.datafirefly.com/en/expertise/woocommerce-subscriptions/).

### Connectors

Sync with an ERP, accounting software, a PIM or a marketplace. Exchanges run through Action Scheduler so orders never get stuck when the remote system is down, and every failure is logged and can be replayed. We have dedicated pages for [Sage](https://www.datafirefly.com/en/expertise/sage-woocommerce-connector/) and [Cegid](https://www.datafirefly.com/en/expertise/cegid-woocommerce-connector/) connectors.

## How we write a WooCommerce extension

- **HPOS compatible**: orders accessed only through WooCommerce objects and queries, never through the WordPress posts table. Compatibility declared and tested with and without sync.
- **Classic and block checkout**: fields and payments integrated in both, through the Store API and the additional checkout fields API.
- **Consistent totals**: a price changed in one place is changed everywhere, in cart, order, emails, invoices and the REST API.
- **Heavy work in the background** with Action Scheduler, so checkout never slows down.
- **WordPress security**: nonces, capabilities, sanitised and escaped data, prepared queries.

## What you receive at delivery

- The extension as an installable ZIP, tested on your WooCommerce version and on a copy of your store.
- The complete source code with no restrictive licence.
- Installation and user documentation.
- 12 months of compatibility updates and bug fixes.

## What drives the price of a WooCommerce extension

Our quotes start at €1,500 and stay fixed once the scope is approved.

| Factor | Effect on the quote |
| --- | --- |
| Checkout | An extension outside the checkout is simpler; anything touching checkout must be built and tested for both checkout versions. |
| Price calculation | Displaying a price is quick; a rule that changes totals has to be checked against taxes, coupons and refunds. |
| External integration | A documented API, or file exchanges with retry on error. |
| Extensions already installed | Subscriptions, a multi-currency plugin or an existing B2B plugin add compatibility cases to test. |

## Extensions we have already built

- [Dynamic pricing](https://www.datafirefly.com/en/product/dfdynamicpricing-en/): price rules by quantity, customer, category or period.
- [Quote management](https://www.datafirefly.com/en/product/df-woo-quotes-woocommerce-quotes/) with PDF and Stripe payment.
- [Pre-orders](https://www.datafirefly.com/en/product/pre-order-manager/) for out-of-stock or upcoming products.
- [Accounting export](https://www.datafirefly.com/en/product/dfwoo-fec/) to FEC, Sage 100, EBP and Pennylane.
- [EU VAT OSS](https://www.datafirefly.com/en/product/vat-oss-autopilot-en/) calculated in real time with return preparation.
- [Margin dashboard](https://www.datafirefly.com/en/product/real-profit-dashboard-en/) per order and per product.

## Around the extension

We also work as [WooCommerce developers](https://www.datafirefly.com/en/expertise/woocommerce-developer/) on existing stores, for [audits](https://www.datafirefly.com/en/expertise/woocommerce-audit/), [maintenance](https://www.datafirefly.com/en/expertise/woocommerce-maintenance/) and [Core Web Vitals optimisation](https://www.datafirefly.com/en/expertise/woocommerce-core-web-vitals-optimization/). If your need is not about the store, see our [custom WordPress plugin](https://www.datafirefly.com/en/expertise/wordpress-plugin-developer/) page.