• GamersGate[www.gamersgate.com] - All games show what DRM they use (e.g. Steamworks). If they use none, it says they're DRM-free.
  
• GOG[www.gog.com] - All games are DRM-free, period. Furthermore, GOG also has the Galaxy client which combines the freedom of DRM-free (because using it is optional) with the convenience of Steam's auto-updating. It also allows you to refuse updates or even do an Update Rollback.
  
• Humble Bundle[www.humblebundle.com] and Humble Store[www.humblebundle.com] - Games offer whatever platforms are indicated in the icons. Games that are DRM-free have a "DRM free" icon. (Some also come with Steam keys, but that's beside the point here.)
  
• itch.io (https://itch.io/) - Most games offer DRM-free downloads -- it'll say "You will get access to the following files:" and list game installers that you can download after you buy the game. (Focused on indie games.)
  
• Playism[playism.com] - Most games offer DRM-free downloads; it'll clearly indicate "will receive a DRM-free copy" or "will receive both a DRM-free copy and a Steam key". (Focused on the games Playism has worked on, but this is a pretty extensive list.)
  
• The developer's/publisher's own web store may offer direct downloads (i.e. DRM-free installers). For example, the Fruitbat Factory[sites.fastspring.com] web store does this.

There are some more niche stores that offer more limited selections, but may still be very useful if they're what you want. For example, if you like visual novels, there are at least two DRM-free stores.

• JAST USA[jastusa.com] - all products are DRM-free.
  
• MangaGamer[www.mangagamer.com] - according to this tweet all their products are DRM-free.

Technically, Steam does offer some games that are DRM-free. But they are not clearly marked on Steam, and there is no comprehensive list of them on the internet. (You can always try asking in the game's forum on Steam though.)




This isn't as good as DRM-free, since you're still stuck with using Steam, but it can be useful if the game doesn't exist in any other form. Many stores are authorized by developers/publishers to sell Steam keys. They include:

• Fanatical[www.fanatical.com] - any game that has a Steam icon. (Formerly known as BundleStars.)
  
• GamersGate[www.gamersgate.com] - any game that indicates Steamworks DRM.
  
• Humble Bundle[www.humblebundle.com] and Humble Store[www.humblebundle.com] - any game that has a Steam icon. (Same place as the "DRM free" icon. Some games may have other DRM icons.)
  
• Indie Gala[www.indiegala.com] and Gala Store[www.indiegala.com] - any game that has a Steam icon.
  
• itch.io (https://itch.io/) - Some games say "You will receive a Steam key."
  
• Playism[playism.com] - most games offer a Steam key. I think the vast majority of games here offer both DRM-free and Steam key, though a few are DRM-free only and another few are Steam key only.

As far as I know, these are first-sale key stores. DO NOT buy from key resellers, which sell you keys that other users picked up from various sources and then sell them, which inevitably involves a bunch of shady people selling keys from questionable sources, such as stolen credit cards or press copies.




If you want to look for good deals on games, use this site: https://isthereanydeal.com/

It'll show you the price history on a variety of stores. Go to each store to check what kind of thing they'll give you (DRM-free or Steam key).

(As far as I know, this site does not list any key resellers.)



I've reposted this here in case it gets lost or deleted.

Please add relevant information to this -- particularly other DRM-free stores.