Acar is a type of vegetable pickle of Maritime Southeast Asia, most prevalent in Indonesia, Malaysia, Singapore and Brunei. It is a localised version of Indian achar. It is known as atjar in Dutch cuisine, derived from Indonesian acar. Acar is usually prepared in bulk as it may easily be stored in a well-sealed glass jar in refrigerator for a week, and served as a condiment for any meals.

South Asian pickle is a pickled food made from a variety of vegetables and fruits preserved in brine, vinegar, edible oils, and various South Asian spices. The pickles are popular across South Asia, with many regional variants, natively known as lonache, avalehikā, uppinakaayi, pachadi or noncha, achaar, athāṇu or athāṇo or athāna, khaṭāī or khaṭāin, sandhan or sendhan or sāṇdhāṇo, kasundi, or urugaai.