Extensions come in two flavors: custom and third-party. Custom is written by a system integrator for a specific client. Third-party is written generically and offered (sometimes free) by a Magento technology partner.
What an extension is
Either way, an extension is code written to extend Magento core for the purpose of adding required functionality. Extensions can themselves be extended — for example, a system integrator might extend a third-party extension to better fit a specific client’s business requirements.
Advantages of third-party extensions
- Speed to market — Instead of developing the desired functionality from scratch, weeks of time are saved by using an existing extension.
- Reduced cost — Most third-party extensions are $200–800. Custom development of the same functionality typically runs into the thousands.
- Reduced technical debt — The third party is responsible for documentation, bug fixes, security updates, and feature additions. You only need to keep extensions up-to-date as part of routine care and feeding.
When custom is the right answer
Third-party extensions aren’t always available, and aren’t always the right fit. Build custom when:
- The functionality is unique to your business model.
- Existing extensions don’t quite fit and would require heavy customization.
- You need code-level control over how the feature behaves over time.
- Compliance or audit requirements demand you control the codebase.
Vetting an extension
Before installing any third-party extension, check: when was it last updated? Does the developer respond to issues? What’s the rating and review count? Does it have a clear upgrade path for the next major Commerce version? An abandoned extension is technical debt — sometimes worse than custom code, because nobody on your team knows how it works.
Adapted from the Adobe Commerce Primer, slide 32. Last reviewed May 2026.