The Gaudi script (Gāuṛi lipi), also known as the (Proto-BAM script) Proto-BAMO script i.e. (Proto-Assamese script, Proto-Bengali script, Proto-Oriya script and Proto-Maithili script) is an abugida in the Brahmic family of scripts. By the fourteenth century, Gaudi script had begun to differentiate and gradually developed into the Bengali-Assamese (Eastern Nagari), Odia, and Maithili script.

The Gaudi script is named after the Gauda Kingdom (Gāuṛ Rājya) of Gauḍa (region) in ancient Bengal. In 1030 AD, the Persian scholar Al-Biruni, in his writings on India, mentioned the ancient Gaudi script of Eastern India. Medieval Gauḍa (region) is currently known as Bengal (region). Despite this name, the script was also used in Assam, Bihar, Odisha, Jharkhand, neighbouring parts of Nepal and Rakhine in Myanmar. The script is called by different names in different regions such as Proto-Assamese, Proto-Bengali, Proto-Maithili, Proto-Oriya in modern time. Which is why Sureshchandra Bhattacharyya suggests neutral names such as the abbreviated Proto-BAM, Proto-BAMO.

The Gaudi script appeared in ancient Eastern India as a northeastern derivative of the Siddham, derived from Gupta. According to the scholar Bühler, the Gaudi (or Proto-Bengali) script is characterized by its cursive letters and hooks or hollow triangles at the top of the verticals. In the 11th century, famous Persian scholar Al-Biruni wrote about the ancient Gaudi script. He mentioned amongst Indian alphabets, Gaudi is used in the purva desa (Eastern County).

The modern eastern scripts (Bengali-Assamese, Odia, and Maithili) became clearly differentiated around the 14th and 15th centuries from Gaudi. While the scripts in Bengal, Assam and Mithila remained similar to each other, the Odia script developed a curved top in the 13th-14th century and became increasingly different.