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Best Period Tracker Apps in 2026
8 period trackers ranked by privacy architecture, features, and price. On-device, server-based, and open source options compared.
How to Evaluate a Period Tracker Where your data lives matters more than feature count. There are two architectures: on device (data stays on your phone) and server based (data is stored on the company's servers). This distinction determines whether your reproductive health data can be shared, breached, or subpoenaed. The FTC's enforcement actions against Flo (2021) and Premom (2023) both involved server based apps that shared data with third parties. On device storage cannot be shared because no company server holds a copy. Source: FTC vs. Flo, January 2021; FTC vs. Premom, May 2023 The Ranking Criteria This list ranks apps by: 1. Data architecture — on device vs. server based 2. Enforcement history — documented regulatory actions or settlements 3. Transparency — open source, published architecture, third party audits 4. Features — cycle prediction, symptom tracking, sync, platform support 5. Pricing — what you pay and what's behind a paywall Privacy architecture carries the most weight. A feature rich app that stores data on servers you can't control still creates subpoenable records. On Device Apps On device trackers store data locally on your phone. No company server holds a co