Sites using the Open Source OpenCart e-commerce system, available in many web hosting packages, can configure their stores to use third party payment processing companies. This enables companies using OpenCart to accept bitcoin from their customers with minimal effort or risk.
European OpenCart Compatible Payment Providers
BitcoinPay.com is a European  Bitcoin Payments processor. It has a OpenCart Bitcoin Payments Plugin which registered users can integrate into their e-commerce stores, to enable them to take payments within the Eurozone, as well as local payments in Czech Koruna, and Polish Zloty. Settlements can be set to remit in any percentage of fiat and bitcoin.
Accept and forward Bitcoins via OpenCart 3.x and 2.3+ extensions
Apirone.com, a bitcoin processing provider, launched a plugin for OpenCart users. Now, all this users are in capacity to accept Bitcoins on their online stores with a fixed commission, regardless of the amount order. No registration needed and no obligation to complete a KYC/AML. No matter who your clients are, or where they come from, merchant will receive their money. In addition, for those you want be completely anonymous during the purchase, they offer you a redirect to the TOR network. SegWit Bitcoin addresses support. Read more: https://apirone.com/integrations/#cms
Direct to Wallet OpenCart Module
Blockonomics has an opencart module that allow merchants to receive bitcoin directly to wallet. All major HD Wallets like blockchain.info, electrum, trezor are supported. The plugin is open source and can be access on github
Old OpenCart Bitcoin Extension
An older extension made by John Atkinson (jga) of  - the original source of this page - is no longer actively maintained as of mid 2013. Information relating to it is below to maintain the record.
An OpenCart payment module that communicates with a bitcoin client using JSON RPC.
This code accurately converts USD to BTC using the up-to-the-minute MtGox average. It is completely self contained and requires no cron jobs or external hardware other than a properly configured bitcoind server. Every order creates a new bitcoin address for payment and gives it a label corresponding to the order_id of the order. It installs like any other OpenCart plugin and it is completely integrated with OpenCart.
OpenCart Bitcoin was first made available on September 21, 2012.
- OpenCart 3.x Bitcoin extension OpenCart 3.x Bitcoin extension, opensource on GitHub
- OcStore and OpenCart 2.3 Bitcoin extension OcStore and OpenCart 2.3 Bitcoin extension, opensource on GitHub
- OpenCart Bitcoin project on GitHub
- Opencart_v2 Bitcoin project on GitHub