In addition to websites, CRDS has client software you can install locally both as complete programs and as a library you can use in your own scripts. The client provides tools for downloading rules and reference files, determining best reference files, updating rules, differencing rules, checking files, checksumming files, naming files, etc.
While CRDS does have a number of public library calls which can be called from your own Python scripts, it should currently be viewed more as a system than as a library, since it includes many active systems (web servers, active database and shared file system intefaces) in addition to the library discussed here.
The demand for most scriptable interfaces is largely new, so if you have a use case you’d like to script, don’t hesitate to ask for it.
CRDS is often installed implicitly as a dependency of the HST or JWST calibration software. These basic installations only include sufficient dependencies to assign best references and fetch them if needed.
To check for CRDS try:
$ crds list --version 7.0.5, master, c95d1cc