This app helps you track menstrual-cycle symptoms day by day and evaluate your records manually following the NER rules (Rötzer), in the spirit of INER. The evaluation stays with you: you place every mark on the cycle chart yourself. The app only does the arithmetic you would otherwise do by hand — the baseline drawn from the six prior low measurements, counts, lines, and statistics (cycle and phase lengths). It computes and displays; it never suggests and never decides. For a reliable interpretation of fertility you need knowledge of the method — from a textbook or a course. The app is in beta — export your data regularly and before every update via Export in the settings. Features: • All your data stays on the device — no cloud, no analytics, no network permission. • Language: German and English — follows your system language or can be switched in the app. • Daily entry of basal body temperature (with exclusion flags for disturbances such as illness, alcohol or a late bedtime), bleeding, cervical mucus in the NER shorthand notation (t, Ø, f, S), optional cervix, pain, sex, and notes. • Evaluation tools: first temperature above the baseline, count of low measurements, mucus peak day, sympto-thermal fertile window, exclusion of disturbed days. • PDF export: export the evaluation as a print-ready PDF. • Import from Drip: bring in existing data from the Drip app (CSV export). • Export and Import in the settings — your data always stays your own. • Open source; licensed under Apache-2.0. Note: "NER Cycle App" is a working title; the final name has not been chosen yet.