free software to remove DRM from Adobe ACSM format

From what I can gather, an .acsm file doesn't actually contain a ebook. It just contains a link that Adobe Digital Editions uses to download an ebook from Adobe's servers. I don't think that a free software program could download the ebook unless it was capable of making itself appear to be a copy of Adobe Digital Editions. That ebook *would* have DRM, and there might be free software capable of removing it, but I can't find any free software that can download the ebook in the first place using the .acsm file.

Any program designed to break DRM is illegal, so as a general rule, breaking DRM is not easy. The one exception I can think of is CSS (used for encrypting DVDs), but that's just because the encryption is so weak that it can be brute-forced very easily (so despite the illegality of it, all kinds of programs designed to break CSS exist; libdvdcss is just the most commonly used).

Have you looked into the DeDRM plugin for Calibre? I haven't used it, but I know that some people swear by it. Not sure if it would work for your ACSM file.

i would recommend the apprentice alf software to remove drm from ebooks https://apprenticealf.wordpress.com/

here is thier awanser to FAQ

Are the tools open source? How can I be sure they are safe and not a trojan horse?

All the DRM removal tools hosted here are almost entirely scripts of one kind or another: Python, Applescript or Windows Batch files. So they are inherently open source, and open to inspection by everyone who downloads them.

There are some optional shared libraries (*.dll, *.dylib, and *.so) included for performance. The source for any compiled