You only need 3 ingredients for homemade jam (no pectin!). Fruit, sugar, and lemon juice (or really any other acid). If you've got those things, then you have everything you need to make your own homemade jam.
Guideline: Any fruit at any amount. Basic sugar to fruit ratio is:
1/4 (52g) cup-2/3 cup (136g) granulated sugar per pound (450g) of fruit
1/2 teaspoon (2ml) acid per pound of fruit (lemon, vinegar, other citrus juice)
Peel fruit then cut into small pieces. Toss in sugar, leave for 1-2 hours or overnight in the fridge wrapped in plastic to macerate. Start at 52g sugar per pound of fruit. Add more after the macerating process if necessary.
*Simmering time will vary based on the amount of fruit used. For 1 pound of fruit expect it to take around 15-20 minutes.
Optional for raspberries: ½ cup (104g) sugar for every pound of fruit.
Put macerated fruit in pot, add 2 tbsps of acid to activate pectin, the chemical that activates the thickening of fruit.
Cool in a metal bowl and ice bath set up.
OPTIONAL: Strain seedy berry jams through sieve or chinois if needed
Store and use as needed.