Open resource for spectroscopic raw data
As a quick fix: To access the IR spectral data of $\ce{HCl}$, I opted for a seach by (Hill) formula  on NIST's web page, which yielded three entries here.  For $\ce{HCl}$ in particular (here) I opted for the first one here, indeed offering the spectrum as image file or as JCAMP-DX.

As in the comment by @EdV, this JCAMP-DX an ASCII file indeed.  Note JDXview by Norbert Haider (Department of Drug Synthesis, University of Vienna, Austria) is a very handy program (only 560 kb, installation free executable) for a quick display of this file by NIST. Via File -> Save, the export of the data in a two-column, tabulator separated .txt file is just a click away.  The program works perfectly well in Windows, and with wine libraries equally in Linux, too.  (The author equally distributes the underlying Delphi / Pascal code.)



Note 1: Because of the tags physical chemistry, and spectroscopy, you may be interested in a python module like jcamp to access either IR, or NMR spectra in the JCAMP-DX formats (there are multiple).

Note 2: Sometimes, all you have indeed is an image (a scanned) spectrum.  If you pay attention and proceed in sections (e.g., $4000 - 2000$, then $2000 - 800\,\pu{cm^{-1}}$) to account for the break on the abscissa in IR spectroscopy, a digitizer like WebPlotDigtizer may be worth to use.  If you want, the program works via a web browser, installation free, with «normal image files» like .png, and since some time with images embedded in a .pdf (think about publications), too.