Wikispaces
- A free wiki host providing community wiki spaces, visual page editing, and discussion areas.
- http://www.wikispaces.com/

Wik.is
- Free wiki hosting service based on DekiWiki. Instant registration, URL format "http://yourtopic.wik.is/". GUI editing, login required to edit. Formerly wiki.com.
- http://wik.is/

Wikidot.com
- Free ad-supported wiki hosting service for non-commercial use, based on Open Source wiki software. URL format is "http://yourtopic.wikidot.com/". Wiki syntax only, interactions with other services, extended and extensible wiki syntax, uploads, f
- http://www.wikidot.com

On-wiki
- Free wiki hosting based on MoinMoin Open Source wiki engine. URLs of form "http://yourtopic.on-wiki.net/". WYSIWYG editing, file upload, custom permissions, ads on each wiki page.
- http://on-wiki.net/

XWiki.com
- Free wiki hosting site with text ads, using Open Source XWiki software. URLs in format "http://yourtopic.xwiki.com/". Immediate setup, WYSIWYG editor, photo album, calendar, wikiblog interface.
- http://www.xwiki.com/

Peanut Butter Wiki
- Free ad-supported wiki hosting with paid upgrades available. URL in format "http://yourtopic.pbwiki.com/". Requires shared password to edit, no GUI, file upload, API.
- http://pbwiki.com/

JotSpot
- Free wiki hosting service; custom software includes calendars, photo galleries and spreadsheets. URL format "http://yourtopic.jot.com/". GUI editing, themes, access control.
- http://www.jot.com/

Wetpaint
- Free wiki hosting service with proprietary software, GUI editing interface, and instant site registration. URL for wikis is "http://yourtopic.wetpaint.com/".
- http://www.wetpaint.com/

Wikia
- A collection of freely-hosted ad-supported wiki communities using the Open Source MediaWiki software. URLs like "http://yourtopic.wikia.com/". Requires 2- to 10-day approval process, single sign-on across all Wikia sites, file uploads, transclus
- http://www.wikia.com

Schtuff
- A free wiki farm with flexible membership and permission options and file upload. Up to 200 MBytes and 3 wikis allowed per user.
- http://www.schtuff.com

EditMe
- Provides wiki and content-managed website hosting.
- http://www.editme.com/

Swiki.net
- A wiki farm offering free hosting of Swiki (Squeak Wiki) based wikis.
- http://www.swiki.net/

SeedWiki
- A Wiki Farm where basic Wikis are free. Offers plugins that allow applications and web sites to be built on a Wiki Framework.
- http://www.seedwiki.com