I wrote an online FITS viewer: https://astro.mellican.com/fitsviewer/. My use case was to grab a single raw sub and convert the FITS file to a high quality JPEG on my big screen (as opposed to a device) for review. I found other online viewers did not stretch the image. This tool performs some basic processing to make it presentable. It does not do any stacking or calibration.
The upload file size limit is currently 50MB and only FITS file types are allowed. Subs will be purged periodically. If you want to keep it on the server a little longer, say for posterity or sharing, let me know (DM me).
Edited by meltaxa, 31 January 2023 - 05:28 AM.