Research on autistic individuals' writing has long focused on weaknesses in structural complexity, organisation, and perspective-taking skills. More recently, awareness has grown that writing can be a strength, as suggested by research on autistic memoirs. To learn more about how well autistic individuals write when they use language for their own purposes, we turned to autistic-authored blogs. Online word usage patterns were analysed for 30 self-identified autistic bloggers and 30 age and gender-matched non-autistic bloggers, assumed to be neurotypical (NT). In addition, blog content was analysed for the range of topics discussed. Topics were categorised according to broad topics including common hobbies (e.g. sports, arts, crafts), preoccupations (e.g. people, vehicles, food, machines), and academic domains (e.g. belief systems, science, numbers, history). Compared to NT bloggers, autistic bloggers wrote in a more complex manner, as measured by word and sentence length and rare vocabulary. Autistic bloggers often wrote about science or other abstract topics rather than discussing daily life events. These findings suggest that one subset of autistic individuals, those who write blogs, are able to write in a more complex style than their NT peers. This may reflect having an intellectual orientation, or, autistic people with sophisticated writing skills are the ones who choose to author blogs. Raising awareness that some autistic individuals can be strong writers will be of broad help to diverse stakeholders, including educators, clinicians, families and autistic individuals themselves.