Open architecture is a type of computer architecture "Architecture (computing)") or software architecture that allows adding, modernizing and changing its components. For example, the IBM PC has an open architecture, while the Amiga 500 personal computer has a closed architecture, where the hardware manufacturer chooses the components, and they are usually not upgradeable.

Open architecture was extended in 1999 to the context of architectural design of buildings through the group Architecture for Humanity"), a project completed in 2015 and continued by the Open Architecture Collaborative.

Open architecture allows potential users to see the inside of all or part of the architecture without any proprietary restrictions. Open business processes related to an open architecture may require some licensing agreements between entities that share architecture information.

Open architecture products can be easily expanded and extended by users compared to proprietary products. Open architecture exposes some or all of the product specifications required by developers and integrators, but also includes those that require licensing at that time. The open architecture system makes use less restrictive for users and other equipment by providing various combinations with portability and interoperability. Open architecture is important in the structure of the network, computers, operating system, etc., including other applications - hardware and application - where software is built to fit those structures, including those that are not open.[1]​.

Representative examples of open architecture include the IBM PC and IBM compatible machines, Unix, Linux, etc. which many vendors adopted.[2]​[1]​ In the case of an IBM PC, as a result of disclosing a basic circuit diagram and BIOS, it was able to create a market by producing enormous software and hardware assets, and gave Microsoft the opportunity to become a giant software company.[3]​.

There are several methods and forms: the adoption of public methods, which include licensing from the beginning to the public as open source, standardize and share with various affiliations and standardization bodies") and those that provide proprietary technologies protected by copyright and patents free of charge or at a low price.