Why two prayer apps show different times

A city-centre coordinate is not your suburb. Across a large metropolitan area the same solar event can differ by several minutes.

Different dawn and night angles move Fajr and Isha first and most. If two apps disagree on Fajr but agree on Dhuhr, the method is almost always the reason.

An app that uses plain sunset and one that applies an interval after sunset will always differ at Maghrib. This is a jurisprudential difference, not a bug.

A stale timezone, a missed clock change, or rounding down instead of up each shift what you see. An exact hour of difference is nearly always daylight saving.

Compare one prayer at a time, confirm both apps use the same coordinates, then compare methods. Fix the location before blaming the calculation.

This is an educational summary drafted editorially and awaiting scholarly review. It is not a personal religious ruling; your marja's guidance and your local religious authority take precedence.