The rebel-held town in the northwestern province of Idlib has become famous for the humourous slogans and banners written in English and Arabic its activists use in weekly protests, the pictures of which have been widely circulated online.
The festival, which started yesterday on the third anniversary of the beginning of the uprising against President Bashar al-Assad, was launched under the slogan "the revolution that faced the military dictatorship is now also facing religious extremism."
"Since we are denied freedom... We must celebrate the dream of freedom," a statement from the festival's organisers said.
Commemorations started with an exhibition by Heba al-Ansari, an artist from the town, about the lives of children affected by the war.
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The organisers said it was the "first display in public inside the liberated areas in Syria."
As part of the festival, activists launched a campaign called "Freedom is a necessity," in which they encouraged participants to write verses from the Koran that counsel against violence on walls around the town.
Matar has long campaigned against both Assad's regime and ISIL, which kidnapped his brother Mohammed Nour last year and has yet to release him.
As part of the Kafranbel commemorations, which continue until Tuesday, there will also be a "street cinema" in the town, with documentaries about Syria to be screened at three open-air locations.