Of the five companies owned by Tickmill above, the safest subsidiary is Tickmill UK Ltd which is regulated by the FCA UK because the FCA UK is a credible regulator. However, Tickmill UK does not accept clients from countries other than the UK, so clients from Indonesia cannot register there. Indonesian clients are usually directed to Tickmill Seychelles (SC) so the security is less guaranteed.
I personally have traded for 6 months at Tickmill SC with small capital under $1,000 and the service is satisfactory: small spreads, never requote, fast deposits and withdrawals (I use Fasapay). However, I do not recommend trading there using large funds (>$5,000) because the regulation is less guaranteed.
A more complete Tickmill review can be read here.