Contributing to httpstan

httpstan is a shim allowing clients able to make HTTP-based requests to call functions in the Stan C++ library’s stan::services namespace. httpstan was originally developed as a “backend” for a Stan interface written in Python, PyStan.


  • Provide access to frequently-used functions in Stan C++ library’s stan::services namespace.

  • Minimize toil. Maintaining httpstan should require as little time as possible.


  • Provide access to functions other than those in the stan::services namespace. There are only three exceptions to this non-goal: model_base_crtp.log_prob, model_base_crtp.write_array, and stan::model::log_prob_grad.

If these goals and non-goals strike you as restrictive, we kindly remind you that httpstan is open source software which you are free to fork and customize.

How to Make a Code Contribution

Code contributions must be readable and easy to understand. httpstan emerged out of a rewrite of an existing piece of software (PyStan) which was difficult to maintain. httpstan aims to be maintainable.

See Contributing to PyStan in the PyStan repository. Contributions to httpstan follow the same guidelines.

There is one important difference between httpstan and PyStan. httpstan provides access to Stan functions via an HTTP-based REST API. This REST API follows the conventions described in the document API Design Guide and the Google JSON Style Guide <>.