Methodology

Software revenue definition
Software companies are ranked according to their revenues coming from 'prepackaged' software sales. Revenues from subscription and support activities (also called 'maintenance' contracts) are included. Revenues from service activities such as consultancy, training, custom software development and system integration are excluded. Revenues from hosted software solutions (Software as a Service) are included depending on the level of standardization of the offering: if no significant customization occurs, the revenue is fully recognized; if the offering involves customization services and/or substantial hosting services, the resulting revenues are recognized only partially as software revenues. 

Sources
Data is gathered from SEC filings, annual reports and corporate websites. In some cases additional information is requested from investor relations departments, or obtained from market research agencies and internet media.

Comparability
To make company revenues comparable, calendar year revenues are used for the list. Corrections are made for financial years that do not match calendar years. Corrections are also made to eliminate currency differences: all revenues are presented in US dollars. The exchange rate at the end of the calendar year is applied in the conversion.

Uniformity
Although it is attempted to gather and present all data in a uniform way, differences in accounting policies are likely to provide minor distortions in revenue recognition. 

Reproducibility
All revenue calculations and the data sources are published so that the information on the list can be verified independently. 

Integrity
The Software Top 100 is made by independent researchers from the Top 100 Research Foundation. Companies do not (can not) pay to be on the list. The only qualification for a position on the list is: sufficient software revenues.

Timing
A fresh edition of the Software Top 100 is published annually, after the software industry has published the necessary annual reports. Typically, publication of the fresh edition takes place in the second half of July.