Free ad-supported streaming television (occasionally, free ad-supported television, commonly abbreviated as FAST) is a category of streaming television services which offer a combination of traditional linear television programming ("live TV") on-demand programming, live broadcasts (e.g. sporting events) and studio-produced movies without a paid subscription, funded exclusively by advertising akin to free-to-air TV stations.

Platforms following this model include Pluto TV, Rakuten TV (in Japan and many European countries), The Roku Channel, Samsung TV Plus, Tubi, and Xumo. These services stand apart from platforms predominantly featuring user-generated content (like YouTube and Twitch), as well as from subscription-based services (like Amazon Prime Video and Netflix). The term was coined by Alan Wolk to differentiate the category in a December 2018 article in TVREV.

The FAST ecosystem has different layers. The best-known FASTs are the aggregators, which fall into three categories.

These aggregators operate primarily in the United States as of 2025, though some, like Pluto TV, Plex, and Samsung TV Plus operate in additional regions or worldwide.

In addition to aggregator apps, there are FASTs run by a single provider such as Scripps' news division, PocketWatch and FilmRise that also provide their content for use in linear channels on the aggregator apps.

Content on FAST services can potentially cover all television genres as well as films, which are the most popular type of content on the FASTs. Content options can include original and/or archive programming not available through subscription streaming services. Although many FAST channels resemble traditional cable specialty channels, others may have an even narrower focus on a single program or media franchise (such as Cops, Baywatch, Unsolved Mysteries, or the American version of Fear Factor). Such single-franchise channels are usually only practical for shows and franchises with an exceptionally large library of episodes; whereas only 65 to 100 episodes are required for traditional broadcast syndication, a 24-hour FAST channel may require 500 episodes.

While some linear FAST channels are exclusive to specific platforms, others, such as Cheddar and Court TV are distributed through several providers. Such shared channels may include different content and presentation, or may feature less or more total commercials depending on the provider. Linear channels that are carried both on subscription multichannel television and on FAST services usually have various program lineups for each, effectively creating a freemium model; Newsmax TV, which previously carried the same content on both feeds, downgraded its FAST feed to "Newsmax2," with reduced content, to allow the multichannel service to collect retransmission fees from providers and regain leverage it had lost in carriage disputes by offering its main feed free. FASTs owned by major media companies have the advantage of being able to leverage their parent companies' archival libraries.

Variety estimated that 1,455 linear channels were available through major FAST platforms as of June 2022. By May 2024, that number had risen to 1,943.