This is a list of resources, such as dedicated web sites or apps where you can post or pick up used items for free (freecycling). Some are country specific, some are available or have groups in several countries.

This list is open for suggestions and/or comments on the resources. Make a comment, say what country (and if necessary, state and/or region), and post links to the website or relevant app/play store according to the below formats.
Rules: No suspicious links, NSFW links or scam/phishing/malware. The list will be curated, if need be.

Worldwide (common in several countries)

• Freecycle Network - Moderated, free, freecycling only, mainly(?) used in Germany, UK, US
• Craigslist - Unmoderated, some categories paid, mainly sell/buy, some freecycling, mainly used in the US and Canada(?)
  [iOS app] - [Android app]
• Trashnothing.com - Unmoderated, free, freecycling only, active groups in Australia, Canada, UK, US
  [iOS app] - [Android app] - [Open developer API]
• Olio - Unmoderated, free with ads (paid to remove ads), freecycling only
  [Apps vary depending on country, see site]

Germany

• Mundraub - Unmoderated, free, map of free-to-pick fruits, veg, herbs and nuts (mainly in Germany)
  [Android app]
• Kleinanzeigen - Moderated, free, mainly sell/buy, some freecycling.
  [iOS app] [Android app]

Spain

• Gratix - A freecycling app that has karma-based self-moderation.
  [iOS App] - [Android app]

Sweden

• Bortskänkes.se - Unmoderated, free, freecycling only.
  [iOS app] - [Android app]
• Blocket.se - Moderated, mainly sell/buy (paid ads), some freecycling (free)
  [iOS app] - [Android app]

United Kingdom

• Freegle - Unmoderated, free, freecycling only
  [iOS app] - [Android app]

Others

Please add to the list by commenting.