"Free jazz" is jazz you don’t get paid for, goes the old musicians’ bromide. This year, most of the Boston Globe Jazz & Blues Festival was free — meaning you didn’t have to pay to hear it. The only thing you did have to pay for were two big-ticket items at FleetBoston Pavilion (Harry Connick Jr. and Natalie Cole). The freebies started a week ago Sunday with a three-stage circus of local talent at Faneuil Hall and continued with late-afternoon weekday shows in Copley Square featuring Si*Sé, DJ Logic, the North Mississippi Allstars, E.S.T., Brad Mehldau, and Shannon McNally. It would be nice to return to the bigger Globe fests of yore, even if that meant a few more non-free events. Yet it was gratifying to see crowds responding to jazz they might never have heard otherwise.

The one show I caught in the Square was a relatively straight-ahead affair with two piano trios. The Esbjörn Svensson Trio (E.S.T.) is the latest crossover hope from Columbia records. The E.S.T.’s are notable mostly for the superb dynamic balance and the sheer beauty of their sound, which came through despite the outdoor amplification. Svensson and crew create approximations of Keith Jarrett–like ’70s funk, with the same zesty single-note runs over cyclical vamps. The vamping wears after a while, and — especially in the slow tunes — one begins to yearn for some action, rhythmic or harmonic. But just when the trio’s placid loveliness began to pall, bassist Dan Berglund took an electric-guitar-like solo with his bow, all buzzing distortion and spiky rhythms.

Brad Mehldau’s group are probably the most celebrated piano trio in jazz now, known for the leader’s remarkable independence in each hand and stunning harmonic depth, and for their three-way taffy pull with the beat. They fared less well with the sound system than E.S.T. did on Thursday — Larry Grenadier’s bass often projected with a toneless percussive thud. But the beat went this way and that — they hardly played a straight 4/4 with walking bass all afternoon — and Mehldau performed two extended cadenzas, one on Lerner & Loewe’s "I’ve Grown Accustomed to Her Face" and one on Ted Koehler & Harold Arlen’s "Get Happy," that were thrilling.

In the former, the song structure got reshuffled, as if Mehldau were some organic sampler, with fragments of melody showing up in different places, accompanied by dissonant chordal moans. The latter was equally abstract, Mehldau working up the tune into a flurry of two-handed chording and parallel runs up and down the keyboard. Then the melody appeared again, plucked one note at a time in the midst of rushing up-and-down patterns — Mehldau apparently had a spare finger on his left hand. It was long and demanding set of "pure" jazz (even if it included a Radiohead song), but the rapt crowd crowed enthusiastically.

Vocalists headlined the closing event at the Esplanade Hatch Memorial Shell this past Sunday. Nnenna Freelon is an attractive woman with an attractive voice who these days is singing middle-of-the-road versions of Steve Wonder. The male vocal sextet Take 6 did jazzy harmonies, made vocal impersonations of drums and bass, sang uplifting lines like "I’m gonna win" and "What the world needs now is love" (but not the Bacharach version), and got the crowd roaring with their vocalise of crushing hip-hop beats and cymbal splashes.

On his good days, Branford Marsalis takes familiar patterns from the likes of Sonny Rollins and — especially — John Coltrane and makes them his own through sheer force of will. At the Hatch, he came out blazing on tenor sax with drummer Jeff "Tain" Watts’s "Mr. J.J.," and his soprano take on Ornette Coleman’s "Giggin’ " was airy and full of wit, he and pianist Joey Calderazzo taking advantage of that tune’s odd twists and turns. But the Kenny Kirkland ballad "Tonality of Atonement" was a bit sleepy, and after that, the band never really found their groove.

The tenor player in the Dave Holland Quintet, Chris Potter, knows his Coltrane too, but in the band’s opening set on Sunday he mixed up his patterns continually, alternating speedy Tranish scales with R&B blues licks or free-jazz squawks, and he got his biggest ovations after one of his more demanding free romps. The tunes imposed tricky time changes and harmonies on the players — half-time passages, double time, funk, and "swing." The themes were long-lined and complex (Potter usually delivered them with trombonist Robin Eubanks playing counterpoint). But the quintet (which also included vibist Steve Nelson and drummer Billy Kilson) were so sure that, after their lengthy solo explorations, the theme would return as familiar as an old friend, deeper now for the experience they had brought to it. Maybe the next time Holland returns to town he’ll greet an even bigger crowd than he has in the past — a crowd willing to pay.