The Vensim Model Reader is free software which allows you to publish models constructed with Vensim and distribute them to other people. Your model and the Vensim model reader can be copied and passed to as many people as you want, giving people access to your model without their needing to purchase Vensim.
The Model Reader is an application that allows read-only access to models created with Vensim. The model must be either published as model (.vpm) or application (.vpa) or saved as a Vensim format (.vmf) binary file (normal Vensim models are saved as text .mdl files). Publication allows you control over what can be seen by the people you send your model to. You can distribute the Model Reader free with your models so that others can simulate and analyze the models without using Vensim itself.