This Period-Tracking App Actually Keeps Your Data Private ⁠81%

By Beth Skwarecki⁠31%

7/20/2026, 8:30:00 PM

BS Summary: This article contains 25 faulty reasoning types, including Appeal to Authority, Hasty Generalization, and Halo Effect, with Negativity Bias as the most egregious example at 22.9% saturation with 106 hits. Analysis detected 1,001 faulty-reasoning hits from 462 analyzed words, generating a BS Score of 72.2% and a BS Rank of ⁠81% (4,162 of 20,921 articles). This article is worse (more manipulative) than 80.10% of the article peer group.

Period tracking is a simple job that plenty of apps can do. 
But most apps these days-including those that track health data-store information about you on their own servers and sometimes even share that data with advertisers. 
The Mozilla Foundation has tested several of the most popular period-tracking apps, and it identified one as better than the rest at keeping your data private: Euki. 
Privacy is especially important for period trackers in light of the political and legal battles that surround abortion and birth control. 
We know that police have used other data, like messages and search history , to prosecute people for alleged abortions. 
It's understandable if you don't want tech companies to keep or share data about your reproductive health. 
Our sister site PCMag has a guide here to tracking your period privately . 
They recommend Apple Health or DIY methods like coded notes on a calendar. 
Recently, the Mozilla Foundation did a privacy audit of six of the top period tracking apps . 
It found serious privacy flaws in Stardust, SpotOn, Period Calendar, Flo, and Clue, but held up Euki as the best of the bunch: "We strongly recommend Euki for anyone who puts privacy first." 
How to install and use Euki privately 
Euki is available for both iOS and Android . 
The app is free, with no in-app purchases, and the Apple App Store reports that the developer does not collect any data from the app. 
You don't need to create an account to use the app; it starts working as soon as you install it. 
Most importantly, your data is stored locally on your phone and not sent to any servers. 
Most period-tracking apps, including the more privacy-focused ones that say they encrypt or anonymize your data, still store your data on servers that the company has access to. 
Some say they would fight a subpoena if they were asked to hand over data; but it's probably better not to give your data to a company in the first place. 
Euki has a few other privacy features. 
You can set a PIN when you install the app, and a fake PIN that will hide your data. 
(When I enter the fake PIN, I get a message that the app is having technical difficulties and I should try again later.) 
You can tell Euki to delete your previous data, either by tapping a button in settings or by setting up a schedule to regularly delete old data. 
As for the app's features, you can log just about anything to a given day. 
There are categories for bleeding, emotions, body symptoms, sexual activity, and more. 
You can track appointments and even things like when you check the strings on your IUD. 
Article reasoning-pattern comparisonThis article: 7.1%Beth Skwarecki: 1.5%Lifehacker: 2.2%Confirmation Bias7.1%This article: 0.0%Beth Skwarecki: 0.8%Lifehacker: 2.3%Anchoring Bias0.0%This article: 9.5%Beth Skwarecki: 2.7%Lifehacker: 3.0%Availability Heuristic9.5%This article: 2.6%Beth Skwarecki: 0.8%Lifehacker: 1.0%Representativeness Heuristic2.6%This article: 0.0%Beth Skwarecki: 0.2%Lifehacker: 0.2%Hindsight Bias0.0%This article: 0.0%Beth Skwarecki: 2.1%Lifehacker: 2.6%Overconfidence Bias0.0%This article: 7.8%Beth Skwarecki: 2.6%Lifehacker: 5.2%Framing Effect7.8%This article: 3.7%Beth Skwarecki: 1.0%Lifehacker: 2.3%Loss Aversion3.7%This article: 0.0%Beth Skwarecki: 0.9%Lifehacker: 0.9%Status Quo Bias0.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.1%Sunk Cost Effect0.0%This article: 6.7%Beth Skwarecki: 4.2%Lifehacker: 4.3%Optimism Bias6.7%This article: 6.7%Beth Skwarecki: 0.6%Lifehacker: 1.2%Pessimism Bias6.7%This article: 22.9%Beth Skwarecki: 4.1%Lifehacker: 4.1%Negativity Bias22.9%This article: 0.0%Beth Skwarecki: 0.5%Lifehacker: 1.2%Self-Serving Bias0.0%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.3%Fundamental Attribution Error0.0%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.1%Actor-Observer Bias0.0%This article: 0.0%Beth Skwarecki: 0.5%Lifehacker: 0.6%In-Group Bias0.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.1%Out-Group Homogeneity Bias0.0%This article: 18.2%Beth Skwarecki: 1.2%Lifehacker: 4.3%Halo Effect18.2%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.1%Horn Effect0.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.0%Dunning-Kruger Effect0.0%This article: 8.7%Beth Skwarecki: 0.7%Lifehacker: 1.0%Recency Bias8.7%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.4%Primacy Effect0.0%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.1%Blind-Spot Bias0.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.0%Ad Hominem0.0%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.0%Straw Man0.0%This article: 22.1%Beth Skwarecki: 4.5%Lifehacker: 3.8%Appeal to Authority22.1%This article: 6.1%Beth Skwarecki: 2.4%Lifehacker: 1.8%False Dilemma6.1%This article: 6.7%Beth Skwarecki: 0.5%Lifehacker: 0.6%Slippery Slope6.7%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.1%Circular Reasoning0.0%This article: 21.2%Beth Skwarecki: 4.9%Lifehacker: 5.5%Hasty Generalization21.2%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.1%Red Herring0.0%This article: 0.0%Beth Skwarecki: 0.9%Lifehacker: 0.9%Bandwagon0.0%This article: 14.3%Beth Skwarecki: 2.3%Lifehacker: 2.4%Appeal to Emotion14.3%This article: 3.2%Beth Skwarecki: 0.1%Lifehacker: 0.4%Begging the Question3.2%This article: 4.3%Beth Skwarecki: 1.3%Lifehacker: 1.1%Post Hoc (False Cause)4.3%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.0%Tu Quoque0.0%This article: 4.3%Beth Skwarecki: 0.3%Lifehacker: 0.4%Burden of Proof4.3%This article: 0.0%Beth Skwarecki: 0.2%Lifehacker: 0.1%Appeal to Nature0.0%This article: 0.0%Beth Skwarecki: 0.4%Lifehacker: 0.1%Composition/Division0.0%This article: 5.0%Beth Skwarecki: 5.0%Lifehacker: 3.1%Anecdotal5.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.1%No True Scotsman0.0%This article: 8.7%Beth Skwarecki: 2.2%Lifehacker: 2.6%Ambiguity (Equivocation)8.7%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.0%Gambler’s Fallacy0.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.2%Middle Ground0.0%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.1%Personal Incredulity0.0%This article: 0.0%Beth Skwarecki: 0.1%Lifehacker: 0.2%Special Pleading0.0%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.0%Genetic Fallacy0.0%This article: 7.1%Beth Skwarecki: 1.5%Lifehacker: 1.0%Unattributed Quote7.1%This article: 0.0%Beth Skwarecki: 0.3%Lifehacker: 0.2%Quote-first Misdirection0.0%This article: 5.2%Beth Skwarecki: 4.8%Lifehacker: 9.3%Biased Writer Voice5.2%This article: 3.7%Beth Skwarecki: 7.1%Lifehacker: 6.6%Indoctrination3.7%This article: 4.5%Beth Skwarecki: 0.1%Lifehacker: 0.0%Politically Left Leaning Bias4.5%This article: 0.0%Beth Skwarecki: 0.0%Lifehacker: 0.0%Politically Right Leaning Bias0.0%This article: 6.3%Beth Skwarecki: 5.4%Lifehacker: 14.0%Attempt to Sell a Product or S…6.3%

462 words analyzed.

Speakers

3speakers28%attributed speech333writer words
Voice mapSelect a segment to jump to its words
Writer's voice • 8 words • 100.0% coverageWriter's voice • 12 words • 0.0% coverageWriter's voice • 25 words • 0.0% coverageMozilla Foundation • 27 words • 0.0% coverageWriter's voice • 21 words • 100.0% coverageWriter's voice • 20 words • 0.0% coverageWriter's voice • 17 words • 100.0% coveragePCMag • 14 words • 100.0% coveragePCMag • 13 words • 0.0% coverageMozilla Foundation • 17 words • 0.0% coverageMozilla Foundation • 33 words • 100.0% coverageWriter's voice • 7 words • 100.0% coverageWriter's voice • 9 words • 0.0% coverageApple App Store • 25 words • 0.0% coverageWriter's voice • 20 words • 0.0% coverageWriter's voice • 16 words • 100.0% coverageWriter's voice • 28 words • 0.0% coverageWriter's voice • 31 words • 0.0% coverageWriter's voice • 7 words • 0.0% coverageWriter's voice • 19 words • 0.0% coverageWriter's voice • 23 words • 0.0% coverageWriter's voice • 27 words • 0.0% coverageWriter's voice • 15 words • 0.0% coverageWriter's voice • 12 words • 0.0% coverageWriter's voice • 16 words • 0.0% coverage
Selected voice

Mozilla Foundation

100%flagged-word coverage
77 attributed words60% of attributed speech67% writer coverage
0%22.5%45.0%Unattributed Quote+42.9 ptsWriter: 0.0%Mozilla Foundation: 42.9%42.9%Biased Writer Voice-7.2 ptsWriter: 7.2%Mozilla Foundation: 0.0%0.0%Politically Left Leaning B-6.3 ptsWriter: 6.3%Mozilla Foundation: 0.0%0.0%Indoctrination-5.1 ptsWriter: 5.1%Mozilla Foundation: 0.0%0.0%Attempt to Sell a Product -4.5 ptsWriter: 4.5%Mozilla Foundation: 0.0%0.0%

Attribution is sentence-level. Pattern percentages are calculated only from words assigned to that voice.

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Analysis

Hover over highlighted words in the article to view the associated bias or fallacy analysis.