In practice, most people run this in a general tool. A Trello card per recommender with a due-date checklist. A Notion table with status columns: asked, materials sent, reminded, submitted. Google Keep with one note per professor and reminder dates. All free, all fine. The tool matters less than the rule: no recommender goes more than three weeks without a check-in once you have asked.
The materials you send matter more than the tracker. Give each recommender your resume, your draft statement of purpose, and a short list of what you would love them to mention. Professors write better letters when they do not have to guess. Send everything in one organized email, not five scattered ones.
Know the requirements before you ask. Statement of purpose and LOR requirements per program vary: two letters or three, academic or professional, specific portal forms or free upload. Check the application document requirements database at applicationreview.fyi so you ask each recommender for exactly what their schools need.
Letters in, documents tracked in your mobile app to track application documents, deadlines locked. Then get your application audited before you submit at applicationreview.fyi.