The Indonesian word "kecap" and the English "ketchup" come from the same source (most likely from the Min Nan Chinese 鮭汁, meaning something like "fish sauce"), but they mean different things now.
On another note, is both "ketchup" and "tomato sauce" referred to as "saus tomat" in Indonesian?
In Indonesia if you ask for kecap, you will NOT get salty soy sauce. If you ask for "kecap asin", you WILL get salty soy sauce (if they have it).
Kecap manis is the most commonly consumed soy based sauce in Indonesia. If you ask for "kecap" you will be given kecap manis, unless you specify kecap asin. Many warungs do not even have kecap asin, only kecap manis.
If you go to a "bule" restaurant, and ask for ketchup because the just brought french fries, they will bring you saus tomat, which is western style ketchup.