Spelling and grammar are a priority in first language (L1) classrooms. Digital learning has increased significantly around the world, particularly as a result of the COVID-19 pandemic. While the range of online learning for spelling and grammar is very large, there is still no systematic review of the effectiveness of different features and platform characteristics in this area. This systematic literature review summarizes research on online learning platforms for L1 spelling and grammar instruction. We aim to synthesize what is known about online L1 learning environments and to infer the effectiveness and quality of a platform from its design, pedagogical approaches, or technologies used. Special attention is paid to the different features that can be implemented in such platforms. 49 relevant publications were included after a two-step screening process and application of inclusion and exclusion criteria. We found that digital L1 learning platforms are often described rather than evaluated in an experimental study. However, immediate feedback, repetition of tasks, and varying levels of difficulty were described as particularly effective for learning success. While digital learning platforms are widely used, adaptive or machine learning based methods were rarely found. The review suggests future work in adaptive learning environments for L1 learners and the integration of experimental studies.