You bet! You can swap any type of hot pepper you like. Jalapenos are easy to find and not super hot, so that's what I use, but serranos, hot Hatch chiles, or even habaneros if you're brave all work. If you want it hot (or hotter) and don't have hot peppers, you can also add a few pinches of red pepper flakes. And if you prefer just a sweet relish, feel free to leave the hot peppers out. You can use more red, yellow, green, sweet Hatch chiles, or even poblanos if you like.