Krupuk (Indonesian pronunciation: [/kruˈpʊk/]), also known as keropok (Malay pronunciation: [/kəˈro.poʔ/]) and kropek (Filipino pronunciation: [/ˈkro.pɛk/]) refers to traditional deep-fried crackers made from starch combined with flavouring ingredients such as prawn, fish or other seafood. The food has long-standing traditions throughout maritime Southeast Asia and neighbouring coastal regions, particularly in Indonesia, Malaysia, the Philippines, southern Thailand, Brunei and Singapore.

Krupuk, keropok and kropek encompasses numerous regional varieties, ranging from cassava- or rice-based forms to those made with seafood or animal products such as cattle skin. These varieties are widely consumed as snacks, served alongside main dishes, or sold as regional specialities. Certain forms hold strong associations with local cuisines, including krupuk kulit in Java and Sumatra, keropok lekor in Malay Peninsula and amplang in Borneo.

Variants are also found internationally. In the Netherlands the food is known as kroepoek, reflecting historical ties with Indonesia, while in Suriname it forms part of Javanese-Surinamese cuisine. In global markets it is often sold as “prawn crackers” or “fish crackers.” Comparable preparations exist in Vietnam (Vietnamese: bánh phồng tôm; Lao: ແຄບໝູ), southern China (Chinese: 虾片; pinyin: xiāpiàn) and other coastal areas of Asia, where drying and frying provided a practical method of preserving food resources.

Early forms of such foods in the region are thought to have been made from animal skin, which could be preserved, dried and later fried for consumption. Across Southeast Asia, buffalo, cow and pig skins were traditionally kept for non-culinary purposes such as leatherwork or drum-making, while frying or roasting the skin as food represented a way of maximising the use of slaughtered animals in peasant or village settings where little was wasted. The technique of drying and rendering skin before frying, which causes it to puff when cooked, is believed to have developed independently in different regions, including in Thailand and Indonesia.

In Indonesia, historical sources suggest that krupuk was already known by the 9th or 10th century. The Batu Pura inscription mentions krupuk rambak, a cracker made from cow or buffalo skin that survives today as krupuk kulit, often served with the Javanese dish krechek. According to A. G. Pringgodigdo in the Ensiklopedi Umum, its preparation involved cleaning and boiling hides before slicing and drying them for later use. Similar skin-based crackers also appear in other regional traditions, such as the Sundanese dorokdok and the Minangkabau karupuak jangek.

Alongside these skin-based varieties, starch-based crackers developed as a distinct preparation method and eventually became the predominant form across Southeast Asia. Their emergence is often linked to broader food practices in Asia, where root crops, grains and seafood formed important components of the diet. Mixing starch with ingredients such as fish, shrimp or tubers and then drying the mixture provided a practical way to preserve and extend food resources, and similar techniques appear to have arisen independently in multiple parts of maritime and coastal Southeast Asia.

In the Mekong Delta of Vietnam, bánh phồng tôm developed in areas where rice cultivation and shrimp farming were central to local livelihoods, with production in Sa Đéc becoming particularly prominent during the 19th-century Nguyễn dynasty. Through trade along the South China Sea, these prawn crackers circulated widely and showed close similarities to varieties found elsewhere in maritime Southeast Asia. Comparable preparations were also made in southern China, particularly in Fujian and Guangdong, where shrimp paste and rice flour were combined to produce xiāpiàn. Maritime exchange, especially through Hokkien and Teochew merchants, facilitated the spread of such crackers into Southeast Asia, where they were adapted to local tastes and ingredients.

In the Malay Peninsula, local tradition traces the origin of keropok udang (prawn crackers) to the 16th century, when leftover prawn heads from a feast were used to prepare the first crackers. By the 19th century, keropok was documented by the Malay writer Abdul Kadir Munsyi, who noted its production in the Kuantan region. The tradition also extended to the Philippines, where a related preparation known as kropeck is believed to have been introduced through early contact with Malay communities prior to Spanish colonisation. Made from shrimp or fish paste combined with flour and dried before frying, it became a familiar snack and remains widely consumed.