Sawndip (Sawndip: 𭨡𮄫; Zhuang pronunciation: [θaɯ˨˦ɗip˥]) are Chinese characters used to write the Zhuang languages in the Chinese provinces of Guangxi and Yunnan. Sawndip is a Zhuang word that means "immature characters". The Zhuang word for Chinese characters used in the Chinese languages is sawgun (𭨡倱 'Han characters'); gun is the Zhuang term for the Han Chinese. Even now, in traditional and less formal domains, Sawndip is more often used than alphabetical scripts.

Sawndip is also called old Zhuang script, usually used to distinguish it from the Latin-based Standard Zhuang. In Standard Chinese, the old Zhuang script is called Gu Zhuangzi (古壮字; 'old Zhuang characters') or Fangkuai Zhuangzi (方块壮字; 'square shaped Zhuang characters').

Sawndip and its synonyms can be used with a spectrum of narrow to broad meanings. The narrowest meaning confines its use just to characters created by Zhuang to write Zhuang and excludes existing Chinese characters. At its broadest, it includes all the "square" characters used to write Zhuang regardless of whether they are of Chinese or Zhuang origin. However, it is not always possible to determine the origin of a character. In this article the inclusive broader meaning is usually used.

In Chinese, while usually old Zhuang script (古壮字) and square Zhuang script (方块壮字) are synonymous, when used contrastively, the former is restricted to those characters used before the founding of the Republic of China in 1911.

Sawndip is made up of a combination of Chinese characters, Chinese-like characters, and other symbols. Like Chinese it can be written horizontally from left to right, or vertically from top to bottom. The script has never been standardized; some morphosyllables have more than a dozen associated variant glyphs. According to Zhang Yuansheng (张元生), characters not also used in Chinese usually make up about 20% of Sawndip texts, although some texts may be composed almost entirely of characters also used in Chinese.

Different scholars categorize Sawndip in slightly different ways. Displayed below is the estimated frequency of different types of characters by Holm:

According to Bauer, Sawndip characters can be categorized using a more complex system than the six traditional classification principles:

The script has been used for centuries, mainly by Zhuang singers and shamans, to record poems, scriptures, folktales, myths, songs, play scripts, medical prescriptions, family genealogies and contracts, but exactly when it came into being is not known. It is usually reckoned that Sawndip started to be used over one thousand years ago in the Tang dynasty or earlier. However a study comparing Sawndip with the similar but different neighbouring chữ Nôm script of Vietnam suggested that the script started at latest in the 12th century at about the same time as chữ Nôm.