It's safe until Valve decides otherwise. There's no 100% safety, although Archi writes this in the ASF FAQ:

Q: Can I get VAC ban for using this?

A: No, it's not possible because ASF (unlike Idle Master or SAM) does not interfere in any way with steam client nor it's processes. It's physically impossible to get VAC ban for using ASF, even during playing on secured servers while ASF is running. ASF is the only farming program that can currently guarantee that.

I'd say IM offers the least functionality and thus gives Valve the least reason to ban it.

Nice one Archi, ASF seems like a great program. :)

If IM isn't working for you at all, this seems like a good alternative:

https://www.steamgifts.com/discussion/gCxhN/archis-steam-farm-asf-idle-master-alternative-windowslinuxos-x

The only other one I know can get you VAC banned.
Try this instead:
http://psteamcommunity.yuanyoumao.com/groups/idlemastery/discussions/0/365163686050302866/#c365163686070406640

The portable version worked for me, which is the only one available right now on the official website. http://www.steamidlemaster.com/idle_master.zip

The click-once app may be buggy atm. I went ahead and uninstalled it via Windows control panel, remove programs.

If you have an old Windows version (XP) you can try this:
http://psteamcommunity.yuanyoumao.com/groups/idlemastery/discussions/0/365163686068123401/#c365163686069671179

引用自 the killer foxy：

steam idle control on my computer and on the screen written controling by steam idle

Where did you download it from? The official website?

I don't even have a "settings.txt", probably because I uninstalled IM and reinstalled it again in the hope that this would fix it. When I go to File, Settings, nothing happens.

IM thinks Steam isn't running, there are two "Sign in" links on top of each other, the 2nd one "works" as in I can enter my login data, and it says it's storing it, but then nothing changes.

http://i.imgur.com/x665hrR.png

Edit: Uninstalled IM again and am now using the portable version. This one worked on 2nd try (maybe mistyped password first).

引用自 Reggie：

Okay, I just played a match of CSGO casual w/ Idle Master just there, did I fuck myself over and am I going to get another VAC ban?

I accidentally left it open rather than closing it down as I usually do.
How fucked am I from a scale from 1 to 10?

I estimate the chance for this to happen is approximately 1/1000. It's very unlikely, the only possibility would be if Valve only just started banning IM users, which they probably won't ever do.

If you don't mind me asking, how did you get your old VAC ban?

AFAIK VAC doesn't ban for Idle Master yet. This may change in the future but atm it seems safe.

However I think VAC bans for using SAM if you're on a VAC protected server at the same time.

Doesn't IM automatically switch after 2 hours? My setting is "idle games with more than 2 hours individually, then simultaneously". Anyway it appears to be working now, 1 card left after 10,2 hours idling. http://i.imgur.com/gi73BWL.png