# OpenCart Development UK: Extensions, Upgrades and Integrations

Source: https://dijituldevelopments.co.uk/opencart-development/
Updated: 2026-10-10

> dijitul has developed OpenCart stores since about 2011: custom extensions, bulk product loaders and stock feeds, migrations that keep URL structures, EU VAT checkers, a free postcode lookup module built with CraftyClicks and a full KashFlow integration. We upgrade, fix and extend OpenCart 3 and 4 stores. Every job is a fixed-price quote after a free chat.

## Problems this solves

- Your OpenCart store runs on an old PHP version and your host is threatening to switch it off
- An extension upgrade broke the checkout and the original developer has vanished
- Supplier stock and prices are updated by hand, so the site oversells
- You want OpenCart 4 but half your extensions only exist for 3.x
- Every order is retyped into Xero, Sage or KashFlow
- vQmod and OCMOD changes are stacked so deep that nobody knows what modifies what

## Key facts

- We built a full KashFlow and OpenCart integration: automatic customers, invoices on payment, stock and price sync, credit notes for cancellations
- We released a free OpenCart postcode lookup module, built with CraftyClicks
- Past OpenCart work includes bulk product loading, stock feeds, EU VAT number checkers and URL-preserving shop migrations
- OpenCart 4 is on its 4.1 release series; many live stores still run 3.0.x, which uses Twig templates and OCMOD
- Extensions for 3.x usually need rework to run on 4.x because the extension structure changed
- Older OpenCart versions were not written for PHP 8; PHP 8.1 has been out of support since the end of 2025
- Fixed-price quote after a free chat

## OpenCart is where much of our ecommerce work grew up

OpenCart has been part of dijitul's work since around 2011. We built and sold extensions for it, and some of that work became the foundation for everything we do now:

- **KashFlow integration.** A full link between OpenCart and KashFlow that created customers automatically, raised an invoice when payment cleared, kept stock levels and prices in sync, and issued credit notes when orders were cancelled. We later ported it to Magento.
- **Postcode lookup.** A free OpenCart module, built with CraftyClicks, that let customers find their address from a UK postcode at checkout.
- **Bulk product loading and stock feeds** for shops with large or fast-changing catalogues.
- **EU VAT checkers** to validate business customers' VAT numbers.
- **Shop migrations** onto OpenCart that kept the old URL structures, so search rankings survived.

So when you ask us about OpenCart, you are not getting someone who read the docs last week.

## OpenCart 3 or OpenCart 4?

OpenCart 4 is now on its 4.1 release series, with maintenance releases focused on stability and dependency updates. Plenty of live stores still run 3.0.x, and for good reasons: 3.x is mature, and many extensions were never ported.

| | OpenCart 3.0.x | OpenCart 4.x |

| Templates | Twig | Twig |
| Modifications | OCMOD (and vQmod on many stores) | Restructured extension system; events preferred over file modifications |
| Extensions | Large existing marketplace | Smaller pool; 3.x extensions generally need rework |
| PHP | Late 3.0.x releases run on PHP 8; earlier ones need patching | Written for PHP 8 |

Our advice depends on your store. If 3.x does everything you need and your extensions are maintained, patching it to run on a supported PHP version may be the sensible choice. If you rely on abandoned extensions anyway, moving to 4.x and rebuilding the important ones properly makes more sense. We will audit your store and say which.

## Extensions built the OpenCart way

The quickest way to make an OpenCart store unmaintainable is to edit core files. We build extensions that sit alongside the core: controllers, models and Twig views in the extension folders, settings in the admin, and changes to core behaviour made through OpenCart's event system, or through OCMOD on 3.x where there is no event to hook into. That means the store can still be upgraded and other extensions are less likely to clash.

Every extension we write has its own settings page, uninstalls cleanly and is tested on a copy of your store, with your theme and other extensions, before it goes anywhere near the live site.

Common jobs include custom shipping and payment methods, trade pricing by customer group, product options that affect price and weight, custom reports, and checkout changes such as delivery date pickers or [postcode lookup](https://dijituldevelopments.co.uk/postcode-lookup-integration/).

## Stock feeds, imports and accounting links

OpenCart's admin is fine for adding a few products. It is painful for adding five hundred or keeping stock accurate across suppliers. We build importers that read supplier CSV, XML or API feeds, map them to your products, options and categories, apply your pricing rules and log what changed. They run on a server cron, so stock and prices stay current without anyone touching them.

On the accounting side, our original KashFlow integration is the pattern we still follow for Xero, Sage and QuickBooks: create the customer if needed, raise the invoice when payment clears, record the payment, raise a credit note for cancellations, and never create duplicates if something runs twice. See [accounting software integration](https://dijituldevelopments.co.uk/accounting-software-integration/).

## Rescues, PHP upgrades and migrations

Many OpenCart stores we are asked to look at are stuck on old PHP versions, with extensions from developers who have moved on. PHP 8.1 lost security support at the end of 2025 and 8.2 follows at the end of 2026, according to php.net, so hosts are pushing customers upward. We patch themes and extensions for PHP 8, remove dead modifications and get the store onto a supported stack. See [PHP upgrade and modernisation](https://dijituldevelopments.co.uk/php-upgrade-modernisation/).

If OpenCart is no longer the right platform, we migrate stores off it with the same care we used to migrate them on: products, customers, orders and URLs carried across with redirects. Either way, it starts with a free chat and a fixed-price quote. [Get in touch](https://dijituldevelopments.co.uk/contact/).

## What we deliver

- Custom OpenCart extensions and modifications built the OpenCart way
- Upgrades from OpenCart 1.5, 2.x or 3.x, including extension replacement
- PHP 8 compatibility fixes for themes and extensions
- Bulk product import tools and scheduled supplier stock and price feeds
- Accounting integration with KashFlow, Xero, Sage or QuickBooks
- UK postcode lookup, VAT number validation and checkout changes
- Migration to or from OpenCart with URLs and SEO keywords kept

Technologies: OpenCart, PHP 8, Twig, OCMOD, MySQL, KashFlow API, Xero API

## FAQs

### Do you still work on OpenCart?

Yes. dijitul has developed OpenCart stores and extensions since about 2011, including a KashFlow integration and a free postcode lookup module built with CraftyClicks. We still build extensions, fix PHP 8 problems, upgrade stores and connect OpenCart to accounting and stock systems.

### Should we upgrade from OpenCart 3 to OpenCart 4?

It depends on your extensions. OpenCart 4 changed the extension structure, so most 3.x extensions need rework. If 3.x meets your needs and runs on a supported PHP version, staying can be sensible. dijitul audits your store and recommends the cheaper safe route.

### Our OpenCart store broke after a PHP upgrade. Can you fix it?

Usually, yes. Older OpenCart releases and many extensions use code that PHP 8 rejects or warns about. dijitul finds every failure, patches the core where needed and fixes or replaces extensions so the store runs on PHP 8.3 or later.

### Can OpenCart send orders to Xero or KashFlow?

Yes. dijitul built one of the early KashFlow and OpenCart integrations, handling customers, invoices, payments, stock, prices and credit notes. We build the same kind of link to Xero, Sage and QuickBooks using their current APIs.

### Can you import our supplier price list into OpenCart automatically?

Yes. We build importers that read supplier CSV, XML or API feeds, map them to your products and options, apply pricing rules and update stock on a schedule, with a log of every change.

### How much does OpenCart development cost?

We do not publish prices. After a free chat dijitul scopes the extension, upgrade or integration and gives you a fixed-price quote. Further changes are quoted separately before work starts.

## Pricing and contact

Every project gets a fixed-price quote after a free initial chat and a short scoping stage. You own the code and the data. Book a free chat: https://dijituldevelopments.co.uk/contact/ · 01623 650333 · info@dijitul.uk