I have undergone permanent straightening treatment and was told to dye my hair after 20 days. So, I searched for an ammonia-free hair dye and found this one.
1. I bought the 6.1 Dark Blonde Sandre. Inside, I have old highlights and once dyed brown hair, which had faded and turned into a dark blonde color. The shade came out dark, just as it should. Note that treatments can lighten hair up to 2 tones.
2. It is indeed ammonia-free! Anyone who has used this specific dye can tell from the first use! And you should use an activating milk instead of an oxidizing agent! There are specific ones designed to activate with plant-based dyes.
3. It is slightly harsh. However, it is still less harsh compared to other dyes. So, +1.

The reason I gave it -1* is that it smelled like spoiled, moldy plants!
However, due to limited time, as I dyed my hair at night, and I do it frequently, it doesn't smell like ammonia!
Additionally, I don't know the color's durability on the hair. But on the positive side, when rinsing, it quickly stopped releasing color compared to other ammonia-based dyes that I continue to wash for a long time and still release color.

One of the worst hair dyes, supposedly ammonia-free.... My scalp literally burned and it caused a wound. I was using a different dye for months and I switched to try a different shade that the previous dye didn't have... It definitely contains ammonia and the color doesn't hold well regardless of claiming to have 100% coverage.