Zoju is a feedback system designed for serious language learners, with initial support for IELTS preparation. The platform enables learners to practise all four language skills—Reading, Listening, Writing, and Speaking—while receiving detailed feedback on their answers. Unlike traditional tools that grade a single attempt and provide a static score, Zoju maintains a memory of each learner's performance over time. The core capability of Zoju lies in identifying and tracking mistake patterns that learners repeat across multiple practice sessions. For Reading and Listening, the system leverages answer keys to deliver immediate feedback. For Writing and Speaking, which are traditionally harder to self-evaluate, Zoju provides evaluative feedback that highlights specific areas of improvement. This continuous tracking allows learners to see not just how they performed on one exercise, but how their errors evolve or persist over time. Zoju transforms recurring mistakes into dynamic focus areas that inform what the learner should practise next. Instead of presenting isolated scores, the system surfaces longitudinal insights, helping users understand what is actually holding them back. This approach shifts study time from repetitive practice of already-mastered content to targeted improvement of weak spots. The product is free to try: unlimited Reading and Listening practice are offered at no cost, and new users receive 2 complimentary Writing and Speaking evaluations. This tiered access allows learners to experience the full feedback loop before committing to extended use.