Add the berries and orange juice to a medium-sized saucepan over medium heat. Cook for 5-10 minutes, stirring and squishing the berries occasionally until they have broken down a bit.
Add sweetener, to taste, if desired. Stir to combine.
Remove the saucepan from the heat and stir in the chia seeds. The jam will thicken quickly as it cools.
Refrigerate in airtight container.