Depends on how you want to pay.

If you want to pay cash or bank transfer in local IDR (Indonesian Rupiah) then Future.Travel may be a good option for you. Same if you want to pay with Bitcoin or with a credit card.

There are other local agencies like Travelnoka that work well. If you are doing a complicated trip then you should test the customer support from the site before you purchase. Give them a call or a open a chat with them. If they can support you before the purchase they most likely will answer the phone after the purchase.