You aren't paying cash, but you are spending time or "points."
Indie developers need user testing and reviews. They often give away keys to get traction. free random steam keys
If you search "free random steam keys" on YouTube or TikTok, you will see hundreds of videos with titles like "FREE STEAM GAMES UNLIMITED (NO HUMAN VERIFICATION)." These are almost always scams. You aren't paying cash, but you are spending time or "points
Here is what to run away from:
A website shows a list of keys (like GTA V, Elden Ring, Call of Duty). To get the "unlock code," you must complete a survey asking for your phone number, email, or credit card info. Result: You get spam calls; they get paid by the survey company. You get no keys. Here is what to run away from: A
This is a pro-strategy. Occasionally, sites like Fanatical or Humble Bundle will run "Build your own Bundle" where you can get 10 games for $1.00. That is $0.10 per key.
Furthermore, these bundles often include Steam trading cards. You can sell those trading cards on the Steam Community Market. Sometimes, the trading cards from a $0.50 bundle sell for $0.60. You effectively get paid to take the keys.