Pulse green tomatoes and jalapeños in a blender or food processor until chopped, leaving small bits.

In a large saucepan, bring tomatoes, jalapeños, and sugar to a boil. Reduce heat and add in Jell-O until it is dissolved. While stirring, simmer for 20 minutes.

Pour into sterilized jars. Let cool on counter and then refrigerate for up to three weeks.