You have customizable or modular products

If you want to give shoppers a lot of options for customizing the products they buy, an out-of-the-box e-commerce system will not be able to accommodate all of these options for a single product, let alone all of them. Complex orders like these will require a sophisticated custom e-commerce solution to handle them.

There are specific rules for your industry

Not all industries are alike. It's likely yours has unique regulations or rules then using a custom e-commerce solution is a wise idea. This will help you ensure that you comply with the shipping standards of the industry and of each carrier that you use.

You ship for multiple vendors

Another strong reason for using a custom-built e-commerce system, when it comes to shipping, is using multiple vendors. The more vendors you have a relationship with, the more likely it is that you'll need to use multiple carriers and have special shipping needs.

You have custom coupon or promo codes and unique rules

An out-of-the-box e-commerce system may include functionality for coupon codes, but it may also be very rigid or limited in scope. Using a custom-built website allows you to bake in as many rules about coupons and promo codes as required.

You need to integrate with back-end software

The need for integration with other systems and software is a very common one for e-commerce websites. Depending on the back-end software that you use, integrating it with your e-commerce website can be fairly straightforward, or it can require a good deal of work. In the latter case, you'll likely want to use a custom-built website.

Your customers have unique needs

Some businesses service an impatient clientele and want to make the purchasing process as easy and fast as possible, while others would like to create a sense of familiarity, personalization, and friendliness. Depending on your customers and the shopping experience that you want to create, a custom e-commerce website may be the best way of providing it.

You have unique reporting needs

Your customers may want to view a report of all their ordersfrom your website during a given period for compliance reasons. Being able to generate this report for a certain timeframe is a feature that not all ready-made e-commerce solutions possess..

You want to use a specific credit card processor

Not all pre-built e-commerce solutions come with support for all credit card processors. Although most small businesses use their bank's credit card processing service, you may have a good reason for choosing another company, such as lower fees or faster availability of funds.

You have security concerns

The predominant security concern when running an e-commerce website is protecting your customers' personal data, in particular, their payment card information. Using a custom-built website allows you to benefit from the expertise of developers and security professionals who know how best to protect customers' information.

You want to build really great features for your shoppers

If your business is unique, your e-commerce website should reflect that uniqueness by offering special features. Once you've hit the growth stage, you can start building a suite of fancy features that will improve your conversion rates. Therefore, if you want to create a really special customer experience for your shoppers, you'll probably have to strike out on your own with a custom-built website.

You've outgrown your out-of-the-box e-commerce solution

At a certain point, every business hits a "wall" when it comes to their out-of-the-box e-commerce solution. You start to feel growing pains as you realize that the software can't do everything that you want or need it to. The convenience and simplicity of having the software created exactly to your specifications is just too powerful.

You want to connect your inventory or vendors

In order to maintain a healthy number of products in stock at all times, you'll need to communicate with vendors so that you can replenish your inventory when you're running low. Custom-built e-commerce websites can connect to your inventory management system and your network of vendors so that your inventory is handled automatically.