Custom software

Custom software (also known as bespoke software or tailor-made software) is software that is developed specifically for some specific organization or other user. As such, it can be contrasted with the use of out-of-the-box software packages developed for the mass market, such as commercial off-the-shelf software, or existing free software.

This customized approach usually involves a vendor or internal team assessing the client's requirements, creating a tailored system architecture, developing proprietary software, and performing thorough testing to ensure it fits seamlessly with business workflows, data structures, and growth requirements.

In contrast to off-the-shelf software built for mass use, bespoke solutions provide the commissioning organization with complete ownership and control, allowing continuous enhancements without relying on external providers for updates or new capabilities.

Since custom software is developed for a single customer it can accommodate that customer's particular preferences and expectations, which may not be the case for commercial off-the-shelf software. Custom software may be developed in an iterative processes, allowing all nuances and possible hidden risks to be taken into account, including issues which were not mentioned in the original requirement specifications (which are, as a rule, never perfect). In particular, the first phase in the software development process may involve many departments, including marketing, engineering, research and development and general management.

Large companies commonly develop custom software for critical functions, including content management, inventory management, customer management, human resource management, or otherwise to fill the gaps present in existing software packages. In many cases, such software is legacy software, developed before commercial off the shelf software or free software packages offering the required functionality with an acceptable level of quality or functionality became available or widely known. For example, the BBC spent a great deal of money on a project to develop its own custom digital media production and management software, but the project experienced troubles, and after many years of development, was cancelled. A key stated reason for the project cancellation was that it had become clear that commercial off-the-shelf software existed that was, by that point, adequate to the BBC's needs and available for a small fraction of the price.

Custom software development is often considered expensive compared to off-the-shelf solutions or products. This can be true if one is speaking of typical challenges and typical solutions. However, it is not always true. In many cases, commercial off the shelf software requires customization to correctly support the buyer's operations. The cost and delay of commercial off the shelf software customization can even add up to the expense of developing custom software.

Cost is also not the only consideration in the decision to develop custom software, as the requirements for a custom software project often includes the purchaser owning the source code, to secure the possibility of future improvement or modifications to the installed system to handle changing requirements. However, modern commercial off the shelf software often has application programming interfaces (APIs) for extensibility - or occasionally, as in the case of Salesforce.com, a domain-specific language (DSL) - meaning that commercial off the shelf software packages can sometimes accommodate quite a wide variety of customisations without the need to access source code of the core commercial off the shelf software system.

Additionally, commercial off the shelf software comes with upfront license costs which vary enormously, but sometimes run into the millions of US dollars. Furthermore, the big software houses that release commercial off the shelf software products revamp their product very frequently. Thus a particular customization may need to be upgraded for compatibility every two to four years. Given the cost of customization, such upgrades can also turn out to be expensive, as a dedicated product release cycle may have to be earmarked for them. However, in theory, the use of documented APIs and/or DSLs, as opposed to direct access to internal database tables and code modules, for customization can minimize the cost of these upgrades. This is because commercial off the shelf software vendors can opt to use techniques such as: