Owing to the Anugraha of Shreemati MahaLakshmi-Devi and Bhagavan Shree Vishnu we are living in the amazing Kali-Yuga and one of this Kali-Yuga wonders is that you can find PanchaRatra Granthas without any hindrances.
The E-Library from the headline (http://muktalib5.org/digital_library.htm) contains primary PanchaRatra Granthas in TXT/HTML (UTF-8, Velthuis, Harvard-Kyoto, CSX+).
This E-Library is somewhat hidden among other segments of the muktalib5.org website, so below is "how to access"-guide:
Once on the site (http://muktalib5.org/digital_library.htm) go into "Searchable E-Text Library".
Then "Click here to enter digital library". Use username and password marked in yellow (they are striked out, but working).
After that you will be relocated into E-Library. This E-Library is rather small, so no need to use "Search", it will be faster to look through all the titles.
In order to do this, use "BY TITLE"-sorting.
For example, you would like to download "Aniruddha-Samhita" in order to keep searchable HTML-file on your hard drive (hdd) and make search in it via "CTRL+F".
Just click "Aniruddha-Samhita" title in the left window and look into the right window - it has links to Unicode (UTF-8), Harvard-Kyoto and etc.
After that just open, for example, "View in Unicode"-link in new Tab (via right mouse button or via middle mouse button). You will be redirected to the file.
Afterwards press "CTRL+S" in order to save HTML-version on your hard drive.
The list of The PanchaRatra Granthas I have downloaded from this E-Library on 15-jan-2018 night is in the beginning of the post on sepia screenshot!
P.S. If you are interested in the E-Libraries of similar kind, then you can visit #GRETIL# (Puranas, Vedas, Upanishads and etc.) and #SANSKRITDOCUMENTS.ORG# (all kinds of Sanskrit Texts, including rare Stotras and etc.)...
Vishnudut1926, Moscow, January 2018