WTOP-FM (103.5 FM) – branded "WTOP Radio" and "WTOP News" – is a commercial all-news radio station licensed to serve Washington, D.C. Owned by Hubbard Broadcasting, the station serves the Washington metropolitan area, extending its reach through two repeater stations: WTLP (103.9 FM) in Braddock Heights, Maryland, and WWWT-FM (107.7) in Manassas, Virginia. The WTOP-FM studios, referred to on-air as the "WTOP Glass-Enclosed Nerve Center", are located on Wisconsin Avenue in the Washington D.C. suburb of Chevy Chase, Maryland, while the station transmitter is located on the American University campus. Besides a standard analog transmission, WTOP-FM broadcasts over three HD Radio channels, and is available online.

WTOP-FM is the successor to the original WTOP, an AM station at 1500 kHz, which held the WTOP call sign from 1943 until 2006, and adopted an all-news format on March 9, 1969.

All-news radio accounts for all regular programming on WTOP-FM. Presented in an hourly "wheel", this includes CBS News on the Hour; local news fills the rest of the time, with traffic and weather updates every 10 minutes ("on the 8s"), local business news at 10 and 40 past the hour, and sports news at 25 and 55 past the hour. Weather forecasts are provided by a meteorologist from WJLA-TV, while business news is provided by the Washington Business Journal.

Among the recurring segments on WTOP-FM every week: To Your Health, devoted to health topics and related warnings; Sprawl & Crawl, devoted to road construction updates; Friday Freebies, presenting sales and deals from local stores and businesses; Garden Plot, hosted by Mike McGrath; and Data Doctor's Tech Tips, offers tech advice. WTOP also features two daily commentaries hosted by Chris Core and Clinton Yates.

Two contests air on WTOP: the weekly Mystery Newsmaker Contest, and the daily Winning Word.

The station debuted in the late 1940s as WQQW-FM, licensed to Washington, D.C., as a companion to an existing AM station, WQQW in Bethesda, Maryland. In 1951, the two stations changed their call letters to WGMS and WGMS-FM. They operated with a commercial fine arts and classical music format until 2006.

On January 11, 2006, WGMS-FM's call sign was changed to WTOP-FM as the station switched to an all-news format a week prior. The HD Radio digital subchannels of the 103.5 signal originally had broadcast Bonneville International's "iChannel" music format, which features unsigned, independent rock bands on the HD2 channel, and the HD3 channel aired continuous traffic and weather updates. Later iChannel was dropped for an LMA of the HD2 to a group that currently airs programming aimed at the South Asian community in the Washington area. Sometime in or before June 2013, that LMA was replaced with the predecessor to what is now Radio Sputnik. As of July 1, 2017, WTOP-HD2 began broadcasting the feed from WFED (1500 AM), after Radio Sputnik moved its Washington DC-area broadcasting to conventional (non-digital) frequency 105.5 MHz.

In 2006, WTOP dropped its long-standing association with The Weather Channel and began airing weather reports exclusively from WJLA-TV all day long. Previously, WTOP had used weather reports from WJLA chief meteorologist Doug Hill during morning and evening rush hours and The Weather Channel all other times. Until 2015, the station used all WJLA meteorologists, not just Doug Hill. WJLA's "Live Super Doppler 7" has been featured in weather reports as necessary.