The 32-year-old free agent said in a statement that the venue was changed to allow the media to attend after the NFL had planned a private workout at the Atlanta Falcons training center in Flowery Branch.
Kaepernick finished his workout, then met with fans who lined the field after the 40-minute session. Sources for the athlete said representatives from at least seven NFL teams attended the showcase.
The NFL said 25 clubs were present and all 32 teams would have received video footage of the event.
"We are disappointed that Colin did not appear for his workout," the league said in a statement. "Today's session was designed to give Colin what he has consistently said he wants, an opportunity to show his football readiness and desire to return to the NFL.""
The league said it bent over backward for the free agent by allowing him to bring his own video crew and use his own receivers and approving an advertising shoot by sponsor Nike during the workout.
Kaepernick's representatives said in a statement that the media would have been shut out of the Falcons' facility, and they wanted "transparency." They also said the NFL wanted him to sign a waiver they described as "unusual." The league said it was "standard."
"The NFL has demanded that as a precondition to the workout, Mr. Kaepernick sign an unusual liability waiver that addresses employment-related issues and rejected the standard liability waiver from physical injury proposed by Mr. Kaepernick’s representatives," his camp said in a statement.
The former player moved his workout to a high school about 44 miles from the Falcons' training grounds.
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"Our biggest thing with everything today was making sure we had transparency with what went on," Kaepernick said after his workout. "We'll be waiting to hear from [NFL commissioner] Roger Goodell, the NFL, the 32 teams.
"Ball's in their court — we're ready to go."
On Tuesday, Kaepernick tweeted that he's "been in shape and ready for this for 3 years."
The NFL said 25 teams had committed to viewing the workout and the rest of the leagues teams would view video of the session.
On Saturday morning, the hashtag "StillWithKap" began trending on Twitter as celebrities and fans wished the free agent good luck.
Kaepernick's former teammate, Eric Reid, however, expressed concern that the NFL arranging a workout for the former quarterback was a publicity stunt.
During a locker room interview with reporters on Wednesday, Reid — who was wearing a black T-shirt with the hashtag "IMWITHKAP" on it — said: "Every move that the NFL has made up until this point has been PR for them, has been disingenuous, and I don't think that this is any different."
"But, we'll see what happens," Reid, a safety for the Carolina Panthers, said in the on-camera interview, published by the Charlotte Observer.
This man told me he drove two hours to sit outside and support Kaepernick.
Both supporters of Kaepernick and critics were out Saturday with large signs. A number of Kappa Alpha Psi members were also outside the Falcons' facility to show their support for Kaepernick, who is a member of the historically black fraternity.
"California says thank you Atlanta Falcons for giving Colin Kaepernick a 2nd chance," one man's poster read.
Another man outside the training facility had a sign that read "stand up for the flag." He said he wasn't there "to disparage anybody."
"I'm simply here to lift up the big, beautiful American flag," he said.
Kaepernick has not been signed by any team since he opted out of his contract with the 49ers in March 2017 to become a free agent. The athlete made headlines during the 2016 season for kneeling during the National Anthem before games to protest systematic racism.
The action led to intense backlash, including from President Donald Trump who repeatedly tweeted his criticism of Kaepernick and other athletes for taking a knee. In a 2017 interview, Trump suggested that if the NFL would have suspended Kaepernick it would have stopped him from kneeling.