Migrating from Big Cartel to OpenCart is a strategic move from a simple e-commerce platform to a dedicated, open-source e-commerce solution. In 2025, with Big Cartel's limited features, and OpenCart's more features, unlimited products, full control, and MySQL database flexibility, the case for migration has never been stronger.

This comprehensive technical blueprint is designed for store owners, developers, and decision-makers. We will bypass the marketing fluff and dissect the data structures, the exact field mappings, the cost analysis, and the step-by-step execution required to move your data to OpenCart without losing a single byte.

1. The Strategic Pivot: Why Leave Big Cartel?

Big Cartel is a simple e-commerce platform, but it often becomes limiting for businesses that need full control, unlimited products without fees, and deep customization. Moving to OpenCart opens specific opportunities:

💰 Cost Control

The Big Cartel Pain: Big Cartel may have monthly fees, transaction fees, or licensing costs that scale with your business.

The OpenCart Gain: OpenCart is free and open-source. No monthly fees, no transaction fees. You only pay for hosting and domain. Unlimited products, orders, and customers.

🚀 Full Control & Customization

The Big Cartel Pain: Big Cartel may have limited customization options or require technical expertise for changes.

The OpenCart Gain: Full access to PHP codebase and MySQL database. Unlimited customization. Install free extensions or build custom features. Complete control over your store.

🛠 Unlimited Products & Options

The Big Cartel Pain: Big Cartel may have product limits or variant limitations.

The OpenCart Gain: Unlimited products with unlimited product options. MySQL database handles large catalogs efficiently. No artificial limits.

⚡ Multi-Store & Multi-Language

The Big Cartel Pain: Big Cartel may have limited multi-store or multi-language support.

The OpenCart Gain: Built-in multi-store and multi-language support. Run multiple stores from one installation. Perfect for international expansion.

2. The Pre-Migration Architecture Audit

Before touching any data, you must map the terrain. Big Cartel and OpenCart may use different data structures.

A. Understanding the Platform Disconnect

Big Cartel uses API for data access. OpenCart uses MySQL database with REST API for import/export.

Big Cartel Setup: Ensure you have API access configured. Migration tools connect via API.
OpenCart Setup: Ensure OpenCart is installed on PHP hosting with MySQL. Install migration bridge extension if using automated tools.
Product Structure: Big Cartel products map to OpenCart products. Attributes become product options.
Images: Big Cartel images need to be transferred to OpenCart's image directory.

3. Exact Data Mapping: The Blueprint

This is the most critical section for developers. This is how Big Cartel entities translate to OpenCart. We assume the use of an automated migration tool.

🛍 Product Data Mapping

Big Cartel Field (Source)	OpenCart Field (Target)	Notes & Logic
`Product ID`	`product_id`	OpenCart generates new IDs. Use SKU for mapping.
`Product Name`	`name` (oc_product_description)	Direct string transfer.
`SKU`	`sku`	Direct mapping.
`Price`	`price`	Direct mapping.
`Description`	`description` (oc_product_description)	HTML content. Images need re-uploading to OpenCart image directory.
`Category`	`category_id` (oc_product_to_category)	Categories map directly.
`Attributes/Variants`	`product_option` and `product_option_value`	Attributes map to OpenCart product options. OpenCart supports unlimited options.

👥 Customer Data Mapping

Big Cartel Field	OpenCart Field	Critical Logic
`Email`	`email`	Unique identifier.
`Password`	`password` (hashed)	Password migration supported with bridge plugin. OpenCart uses bcrypt. Migration tool handles conversion.
`Address`	`oc_address`	Addresses map directly.

📦 Order Data Mapping

Big Cartel Field	OpenCart Field	Mapping Logic
`Order Number`	`order_id`	Preserve order number in OpenCart order_id or invoice_prefix field.
`Order Status`	`order_status_id`	Map order statuses to OpenCart order statuses.
`Total`	`total`	Direct mapping with currency conversion if needed.

4. The Toolkit: Selecting Your Vehicle

You have three vectors of attack for this migration. Choose based on budget and technical capability.

Option A: Automated Cloud Migration (Recommended)

Tools: Shopping Cart Mover, LitExtension, Cart2Cart

Specialized tools that connect via API and OpenCart REST API or bridge extension.

✅ Pros: Handles API complexity, preserves relationships, formats data for OpenCart automatically.
❌ Cons: Cost scales with data ($200 - $400). Requires OpenCart bridge extension installation.

Option B: CSV Import

Tools: Big Cartel CSV Export + OpenCart CSV Import

Export from Big Cartel, format for OpenCart, and import manually.

✅ Pros: Lower cost, direct control.
❌ Cons: Manual work required, may lose some data relationships. Limited to products and categories.

Option C: Custom Development

Tools: Big Cartel API + OpenCart REST API

Build a custom script using Big Cartel API and OpenCart REST API.

✅ Pros: Complete control, reusable.
❌ Cons: Expensive ($2,500+), time-consuming. Must handle OpenCart's MySQL structure and REST API.

5. Execution Protocol: Step-by-Step

We will proceed using the Automated Cloud Migration method as it is the industry standard for minimizing downtime.

Phase 1: Environment Preparation

1.1. Prepare Target (OpenCart):
Install OpenCart on PHP hosting (PHP 7.4+, MySQL 5.7+). Complete OpenCart installation wizard. Install migration bridge extension if using automated tools. Do not point your domain there yet. Use subdomain for testing.
Tip: Use .htaccess password protection to prevent public access during setup.

1.2. Prepare Source (Big Cartel):
Configure API access in Big Cartel. Generate API credentials or install bridge extension if required. Keep your Big Cartel store live during migration.

Phase 2: The Connection Setup

2.1. OpenCart Access:
Install migration bridge extension on OpenCart. This provides API endpoints for migration tools. Alternatively, use OpenCart REST API if available.

2.2. Big Cartel Access:
Use API credentials from Big Cartel. Migration tool authenticates via API.

Phase 3: Migration Execution

Select what to move. Be careful with these specific settings:

Create 301 Redirects: Check this box if using custom domain. It creates redirects from Big Cartel URLs to OpenCart URLs. Without this, your SEO dies.
Migrate Product Options: OpenCart supports unlimited options. Big Cartel attributes map to OpenCart product options automatically.
Migrate Images: Images are downloaded from Big Cartel and uploaded to OpenCart's image directory automatically.
Password Migration: Supported with bridge plugin. Customer passwords are migrated and converted to OpenCart's bcrypt format.

Phase 4: The Full Migration

Launch the process. The migration tool handles Big Cartel API calls and OpenCart REST API or MySQL import automatically.

Time Estimation: 5,000 products + 10,000 orders usually takes 2-4 hours. Large catalogs migrate efficiently via OpenCart's MySQL database.

Phase 5: Post-Migration Cleanup

5.1. Customer Communication:
Notify customers about the migration. With password migration support, customers can log in immediately (or may need to reset if not using bridge plugin).

5.2. Verify Products:
Check all products migrated correctly. Verify images, prices, and product options. OpenCart's unlimited options support means all variants should migrate.

5.3. Design & Customization:
Choose or customize OpenCart theme. Big Cartel themes cannot be migrated, but OpenCart offers thousands of free and paid themes.

6. Financial Breakdown: Cost of Migration (2025)

What does it actually cost? Here is a realistic breakdown for a medium-sized store (2,000 Products, 10,000 Orders, 5,000 Customers).

Custom Script

$2,500+

Developer Time

Automated Cloud

$249

Average Cost

Agency Service