This paper presents a review of the technologies designed to support writing instruction in secondary and higher education. The review covers tools to support first and second language writers and focuses on instructional affordances based on their technological specifications. Previous studies in this field centred on Automated Writing Evaluation, Automated Essay Scoring and the rarer Intelligent Tutoring Systems, addressing mainly essay writing needs in US secondary school instruction. With technology-enhanced learning becoming more ubiquitous and widespread, new technologies and tools catering to a broader range of genres, pedagogical settings, and approaches are emerging. We present a systematic analysis of 44 tools across 26 quantitative and qualitative features related to writing processes, pedagogical approaches, feedback modalities and technological specifications. The results uncover an imbalance of available tools with regard to supported languages, genres, and pedagogical focus. While a considerable number of tools support argumentative essay writing in English, other academic writing genres (e.g., research articles) and other languages are under-represented. With regard to the pedagogical focus, automated support for revising on the micro-level targeting factual knowledge (e.g., grammar, spelling, word frequencies) is well represented, whereas tools that support the development of writing strategies and encourage self-monitoring to improve macro-level text quality (e.g., argumentative structure, rhetorical moves) are infrequent. By mapping the state of the art and specifying direction for further research and development, this review is of interest to researchers, policymakers, tool developers, and practitioners of writing instruction in higher and secondary education institutions.