Comparison

Blood Oxygen App vs TrialLink

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Blood Oxygen App

Monitor blood oxygen levels and heart rate using your phone's camera or by syncing with your Apple Watch. Track vital signs, share data with your doctor, and access curated health articles. Includes breathing exercises and sleep reports.

Highlights
  • Blood oxygen monitoring
  • Heart rate estimation via camera
  • Apple Watch sync
  • Data logging and export (PDF)
  • Box breathing exercises
  • Sleep reports
Features
Currently charting
Read full description

Monitor your blood oxygen level and heart rate effortlessly with our app and sync your Apple Watch to get alerts about low levels.* Are you worried about your oxygen levels dropping or wondering how your activities affect your blood oxygen? Our app makes it easy to track these vital signs wherever you go. Track and log your vital signs to share with your doctor later, or stay informed about your cardiovascular health with curated articles—all in one app. But hang on, there's more: • Take an oxygen test effortlessly, and conveniently record and monitor your data. • Use your phone’s camera to estimate your heart rate and then easily log your data afterward. • Sync and store your data in Apple Health or retrieve your blood oxygen and heart rate readings from Apple Health. • Log and easily export your blood oxygen and heart rate data into PDF to share with your doctor. • Regain your calm after a stressful experience by practicing box breathing, all within the app! • Receive sleep reports to assist you in achieving your sleep goals. (requires an Apple Watch Series 3 or later with watchOS 8) *Please be aware that to receive push notifications regarding changes in your blood oxygen level or heart rate, you will need an external device such as a pulse oximeter or a smartwatch. Blood Oxygen App is free to download and utilize. However, users can opt for a subscription to access additional features. Your subscription will automatically renew and you’ll be billed based on the plan you choose. You can cancel your subscription at any time in the App Store. Disclaimer: For wellness use only. The App is intended to improve your awareness of general wellness. The App can't be used for diagnostics or medical purposes. The App does not diagnose, treat, mitigate, or prevent any disease, symptom, disorder, or abnormal physical state. Always seek a health care professional or emergency services if you believe you may have a medical issue. Terms of use: https://aboutmeapps.com/terms-of-use/ Privacy policy: https://aboutmeapps.com/privacy-policy/

About

TrialLink

This B2B SaaS platform streamlines clinical trial operations for sponsors and investigators. It provides secure, study-specific environments accessible only to authorized users via direct login credentials. Access is managed by sponsors, not through public sign-up.

Highlights
  • B2B SaaS platform
  • Clinical trial operations
  • Study-specific environments
  • Secure investigator access
  • Sponsor-managed access
Features
Read full description

TrialLink by Kachina Health Your clinical trial, in your investigators' pocket. TrialLink is Kachina Health's purpose-built mobile solution for clinical trial sponsors. Deploy a fully configured study environment to your entire investigator network. Keep your sites aligned, informed, and focused on what matters most: enrolling patients and executing your protocol. For Sponsors & CROs Configure study-specific environments for your investigators and their research teams. Push everything they need directly to their phones. Key protocol details, such as inclusion/exclusion criteria and the schedule of assessments, training manuals and videos, and detailed enrollment metrics. All sponsor-controlled, all delivered in real-time. Drive Enrollment Sites with on-demand access to study criteria and site-wide enrollment metrics enroll eligible patients faster. Broadcast enrollment updates and site performance data to accelerate momentum across your study network. Reduce Protocol Deviations Keep your sites running clean by ensuring the latest, key protocol details are easily available by investigators and research teams. Enhanced Sponsor-to-Site Communication Replace fragmented emails and texts with targeted push notifications, structured document libraries, and a single source of truth for your entire investigator network. Enterprise-Grade Security HIPAA-aligned database environment, encrypted file storage, and sponsor-controlled app access. All tested with the latest AI security models. Built for the regulatory demands of clinical trial operations. For Investigators & Site Teams TrialLink puts your clinical trial in your pocket. Access protocols, training materials, and enrollment metrics in real-time. Never miss a critical update from your sponsor again. If your sponsor isn't using TrialLink yet, ask them about it. Access to TrialLink is provided by your trial sponsor. If you are an investigator expecting access to a study, contact your sponsor or CRO for login credentials.

Screenshots

Blood Oxygen App4 screens
TrialLink3 screens

Verdict

The call

The clearest difference is in-app purchases: TrialLink at none against Blood Oxygen App's 14. TrialLink also leads on rating (5.0 vs 4.6). Blood Oxygen App's advantage is ratings volume (31K vs 4) and chart position (#31 vs unranked). On price, ads, device support and iOS requirement there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Both are free to download. Blood Oxygen App sells 10 in-app purchases, starting at $2.99 per 7 days. TrialLink asks for nothing beyond the download.

ReceptionRating · Positive reviews · Number of ratings

TrialLink holds the better App Store score, 5.0 against 4.6. That said, the two scores are not equally well evidenced: Blood Oxygen App has 31K ratings behind it against 4, so its average is the more settled of the two.

UpkeepUpdate frequency

Blood Oxygen App ships an update every 2 weeks, TrialLink every 5 weeks. The most recent releases landed on October 31, 2026 and October 15, 2026 respectively.

Scorecard6 real differences · 5 level
Blood Oxygen App versus TrialLink: the parameters behind the verdict, then further details
ParameterBlood Oxygen AppTrialLink
PriceFreeFree
Rating4.6 (31K ratings)5.0 (4 ratings) — better
Positive reviews25.7% of reviews—
Number of ratings31K — better4
Update frequencyEvery 2 weeks — betterEvery 5 weeks
AdsNoNo
In-app purchasesYesNo — better
MonetizationFreemiumFree — better
Best chart rank#31 — better—
DevicesiPhone, iPod, Apple WatchiPhone, iPad, iPod
Requires iOS15.0 — better15.1
Further details — not scored
Size317 MB37 MB
Age rating12+17+
DeveloperAboutMe Apps, Inc.Kachina Health, LLC

Customer experience

Blood Oxygen App

All ratings31,367 ratings
Positive89.9%
Neutral4.5%
Negative5.5%
Written reviews855 reviews
Positive25.7%
Neutral3.5%
Negative70.8%

TrialLink

All ratings4 ratings
Positive100.0%
Neutral0.0%
Negative0.0%

Bugs and requests

Blood Oxygen App

Reported bugs

3 issues
  • App crashes and freezes frequently
  • Inaccurate heart rate and oxygen level readings
  • Compatibility issues with certain Apple Watch models

Requested features

3 requests
  • Add audible/vibration alerts for low oxygen levels
  • Improve automatic oxygen level monitoring
  • Provide more control over reading frequency

TrialLink

Not enough reviews yet to summarise bugs or requests.

In-app purchases

10 purchases

Blood Oxygen App

Subscriptions10
  • Premium features set$2.997 Days
  • Pulse oximeter for Apple Watch3 Days trial$9.991 Month
  • Premium month$9.991 Month
Show 7 more
  • Premium month2 variants$12.991 Month
  • Premium features (all)7 Days trial$19.991 Year
  • Premium$19.991 Year
  • Premium features set7 Days trial$24.991 Year
  • Premium features set$24.991 Year
  • Blood Oxygen+Body Temperature$29.991 Year
  • Premium year$39.991 Year
None

TrialLink

No in-app purchases

Questions

Is Blood Oxygen App free?
Blood Oxygen App is free to download, with in-app purchases available.
Is TrialLink free?
TrialLink is free to download, with no in-app purchases.
Which has better reviews, Blood Oxygen App or TrialLink?
TrialLink is rated higher. Blood Oxygen App averages 4.6 out of 5 from 31K ratings, while TrialLink averages 5.0 from 4 ratings.
Do Blood Oxygen App or TrialLink have ads?
Neither Blood Oxygen App nor TrialLink shows ads.
Which is updated more often, Blood Oxygen App or TrialLink?
Blood Oxygen App ships an update every 2 weeks, and TrialLink every 5 weeks. Most recently, Blood Oxygen App was updated on October 31, 2026 and TrialLink on October 15, 2026.

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