There are at least seven Different Tour Companies that tour guests on the Freedom Trail: 

The Freedom Trail Foundation :Daily tours every hour on the hour from 11-4 from Boston Common, every hour on the half hour from 10:30-3:30 from Faneuil Hall (Bostix Booth from April-November. Limited tour availability in off-season. These are the tours of the Freedom Trail Foundation. 

Lessons on Liberty: Daily tours: Mon-Fri 10am, 1:30pm, 2:30pm, Sat/Sun 10am, 12:30pm, 1:30pm, 2:30pm Lessons on Liberty tours are Boston's only historian-led Freedom trail walking tours. Lessons on Liberty is also pleased to present a full range of Custom Private Tours of the Freedom Trail, Please inquire for more details.

Boston National Historical Park: Free tours of the Freedom Trail led by National Park Service Rangers. Daily tours begin in mid April and continue through November. All tours begin at the Faneuil Hall Visitor Center. Going on your own? .

Freedom Trail Run: Group runs: Sat/Sun @ 8:30am, Daily runs: by appointment, open year round.  Year-Round Tours Daily at 10 AM and Tuesday Evenings at 6 PM - History and Historic Architecture.  The morning tour can be combined to also see Beacon Hill and Back Bay, so you get to see so much more in a 2-hour walking tour. Other tours available at 12:30 PM and alternative times. Boston CityWalks also does private walking tours of Boston and Cambridge customized for you, with just the right mix of history, architecture and culture.  Arrangements can be made to meet at your Downtown hotel or end at your dining destination.

The Histrionic Academy: Seasonal tours at 10:30am & 11:30am

Boston Town Crier: Seasonal tours Mon-Friday 9:30am, 12:30pm, and 3:30pm, Sat/Sun at 9:30am & 3:30pm.

Here is a link to several free freedom trail maps, including one in Google Maps.

There is an excellent tour guide now on Amazon.

Boston Adventures Freedom Trail Scavenger Hunt- Super-fun and educational A fantastic way to see Boston in just a couple hours! For those interested in history, landmarks and cultural attractions, contact Boston Adventures for more details, the fun is all here! See Quincy Market , Faneuil Hall, Boston Common , The North End , Paul Revere's House , USS Constitution and a lot more. Offering Boston Common or Faneuil Hall starting locations. Park in Faneuil Hall or under the Boston Common or take public transportation to meet Boston Adventures.