Question

SEO question: Is there any tool that I can provide X amount of keywords and generate Rea long tail keywords using the "seed" keywords to produce variations?  

Answer 1

Keyword researcher pro (desktop app).  

Comments

@twelve the best. love that thing for years now. it was like 15$ on some discount.  

Answer 2

I wonder if there is a tool that can help like this. But, Here's a video tutorial about generating keywords from bulk export.  (pretty long, actually it's a guide for beginners)
https://youtu.be/ud4wYQpxGSs

Answer 3

Don't know if its exactly what you are looking for, but seoruler has a good keyword suggestion tool  
https://seoruler.pro/suggest

Answer 4

Ahrefs keyword explorer?  

Answer 5

is also worth a try
https://alsoasked.com/

Answer 6

Try www. keywordshitter. com

Answer 7

I prefer Seoruler since it grabs bing results suggestions as well