Any kind of off-site search engine optimisation is frowned upon by Google. That is to say there is no 100% safe link building
service in the market, even guest posting for SEO violates google's guidelines. Anyone who tells you otherwise that is either lying or delusional.
However there are billions of websites online linking out everyday so the risk of being manually penalised by Google's Web spam team is low - as long as algorithms don't flag out too many "unnatural links" on your website.
That is why we have designed a low and slow package which looks natural to the eyes of Google.
However with that said, we do have experience recovering from penalties and we have implemented measures to reduce the risk of penalties.