Gramatika is a syntectic GEC dataset for Indonesian. The Gramatika dataset has a total of 1.5 million sentences with 4,666,185 errors. Of all sentences, only 30,000 (2%) are correct sentences with no mistakes. Each sentence has a maximum of 6 errors, and there can only be 2 of the same error type in each sentence.We also split the dataset into three splits: train, dev, and test splits, with the proportion of 8:1:1 (with the size of 1,199,705, 150,171, and 150,124 sentences, respectively).