Wu Chinese has four major schools of romanization.
The most popular school, Common Wu Pinyin (通用吴语拼音), was developed by amateur language clubs and local learners. There are two competing schemes; both adhere to the International Phonetic Alphabet (IPA) and are very similar to each other. The initial scheme was "Wu Chinese Society pinyin" (吴语协会拼音, developed around 2005), and it formed the basis of "Wugniu pinyin" (吴语学堂拼音, around 2016). Wu Chinese Society pinyin in general does not mark tones. The name Wugniu comes from the Shanghainese pronunciation of 吴语. Either of them is the default romanization scheme in most learning materials.