I need a tool

i need a tool to suggest me some relevant niches. Please help

Tool to suggest relevant "niches.?
Not sure if you need a tool for this. If you are looking for a buyer intent keyword, just go to amazon.
If you are looking for more of only Adsense based keyword, just put a big site in ahrefs and use the filters to get easy keywords with a decent CPC from the list (Here you obviously won't have a choice for sorting only buyer intent or another type of keywords, You will have to do it manually)
Don't spend much time finalizing keywords in this stage, just pick based on whatever Ahrefs says "KD and all" and arrange everything in an excel sheet.
After this, you can manually check the keywords and broad down to potential niches.

Which tool are you looking for brother?

I don't exactly know what you're looking for. If you want to develop the market in selling items through facebook. You can run campaigns, get a great deal of information from me. For example: I often reach clients on Facebook groups. In the next group step you can go to griper (dot) net to find many similar groups and then interact with people. It's not the most efficient, but it will bring to you some small growth.