These days it seems that every Southeast Asian nation has produced its own version of dried shrimp paste, each with an individual texture, odor and flavor. In general, they can be interchanged in recipes, though it is of course best to use the version pertinent to the cuisine you are cooking.
Indonesian shrimp paste is known as Terasi, which is typically sold in small blocks covered in a plastic wrapping. Terasi (and the Malaysian shrimp paste known as Belachan) is so tightly packed that unlike the Thai version of shrimp paste (Kapi), it is a rather hard block which requires cutting with a knife before using. Boasting a beautiful, dark aubergine hue, Terasi has the strongest, most full bodied aroma when cooked compared to its other Asian counterparts.
The Thai shrimp paste (Kapi), which typically comes in a white plastic tub (though the white tends to take on the purplish hue of the shrimp paste) with a red cap is far more readily available in the West. While the Thai shrimp paste has a slightly milder flavor than the Indonesian Terasi, it is just as beautifully pungent and easier to work with for stir-fry dishes due to its softer consistency. Some markets also carry a Vietnamese brand of shrimp paste though this is the hardest to find of all Asian shrimp paste.
Shrimp paste in general is very salty so it is typically used sparingly. In Indonesian, Laotian and Thai cuisine, this is an ingredients used widely in salads and for chili pastes, which are typically eaten as a condiment to raw vegetables. For people unfamiliar with this ingredient, it’s best to introduce shrimp paste sparingly as to some people its potent odor can be unpleasant. When stir-frying with shrimp paste, it’s important to note that the strong odor will permeate the general area unless you use a strong ventilator in the kitchen or open windows.