Rinse the fresh raspberries under cold water to remove any dirt or pesticides.

In a medium saucepan, combine the raspberries, granulated sugar, and water.

Bring the mixture to a gentle boil over medium heat, stirring occasionally.

Reduce heat to low and simmer for 10 minutes to let the flavors meld and the syrup thicken.

Using a wooden spoon, gently mash the raspberries in the saucepan to release more juice.

Remove the saucepan from heat and strain the mixture through a fine mesh strainer into a bowl.

Stir in the lemon juice until well combined.

Let the syrup cool completely to room temperature, then transfer to a glass bottle or jar and refrigerate for up to two weeks.