This one adds some spoke stretch to the spoke length. You can look in the "log" section to see how much stretch it adds.
https://www.wheelpro.co.uk/spokecalc/
This one gives the same spoke length but without the stretch. Both of these supposedly give the same results as spokecalc (minus the stretch).
https://kstoerz.com/freespoke/
However for my recent build, even though I used these 2 calculators and measured my rim accurately, I still got the spokes 1-1.5mm further deeper into the nipple than where I wanted them to be. It could be that the method I used to measure the rim added an extra millimeter somewhere (I stuck 2 spokes and nipples into opposite holes of the rim at the thread depth that I wanted, and measured the gap between the J bend, but I measured at the end of the bend, which is 1mm longer than at the middle of the elbow where the spoke length is measured to. So I think I accidentally added 2 extra mm to my ERD).
Also ERD depends on who is measuring and where it's measuring to, how deep the end of the spoke is inside the nipple. Some people want it at the bottom of the slot in the top of the nipple head. Other people want it at the very top of the nipple head. The difference will change the ERD by up to 3mm. If you use 12 or 14mm long Sapim nipples, they have the same thread length. 16mm nipples have 1 to 2mm longer threads, so you have to subtract your spokes by that amount if you want to prevent bottoming out. DT Swiss 16mm has longer threads than 14mm, and 14mm has longer threads than 12mm. I don't know the exact difference, but someone in another post said it was 1mm of difference between each, while some other websites claimed it was 2mm of difference.
Here you can see an example of different spoke end depths inside the nipple.
https://kstoerz.com/freespoke/tech-threadengagement.php