ABG Expert vs OpenEvidence
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
ABG Expert
This medical tool provides accurate and flexible acid-base analysis for healthcare professionals. It offers detailed explanations, customizable ranges, and advanced features like anion gap correction and A-a gradient adjustments for various patient conditions and locations.
- Validated accuracy with real-world testing
- Plausibility checks for physiologically impossible data
- Automatic anion gap correction with albumin
- Detailed explanations with equations
- Separate or combined analysis of ABG, anion gap, A-a gradient
- Customizable normal ranges for anion gap and delta gap
- Age and barometric pressure adjustments for A-a gradient
- Support for SI and non-SI units
- Color-coded results and differential diagnoses
- Adjustments for chronic respiratory conditions
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ABG Expert™ is simply the best acid-base analysis tool with features available in no other app. Designed and tested by practicing physicians, ABG Expert is trusted by medical professionals for unparalleled accuracy, flexibility, and power while remaining completely intuitive to use. Whether you are a physician, nurse, respiratory therapist, paramedic, or student, ABG Expert is your ideal acid base analysis app. Accuracy- • ABG Expert has been validated using extensive testing under real-world conditions. • No need to worry about entering physiologically impossible data by mistake. Data is checked for plausibility and for internal consistency using the Henderson-Hasselbalch equation. • An accurate analysis depends on an accurate anion gap. ABG Expert has you covered with automatic correction of the anion gap when albumin is provided. • Never again wonder about how a result was obtained. Detailed explanations include easy-to-understand equations so you can be sure the calculations are correct. Flexibility- • Need the arterial blood gas analysis, but not the anion gap or A-a gradient? No problem. ABG Expert can analyze the data for all three results separately or together. • Set the normal anion gap range based on the normal range at your institution. Or, use your patient’s own baseline anion gap to maximize your sensitivity to detect disorders. • Caring for an 80-year-old patient in Denver? Provide age and barometric pressure, and ABG Expert automatically adjusts interpretation of the A-a gradient. • Need more specificity? Adjust the normal delta gap range based on the literature you follow in your practice. • ABG Expert works as well in Bangkok as it does in Boston with full support for SI and non-SI units. Power- • Color-coded results allow for rapid analysis in critical situations. One additional click gives you a detailed differential diagnosis and additional recommendations. • Concerned about a new problem in your patient with advanced COPD? ABG Expert can adjust its calculations for chronic respiratory conditions so you can detect additional disorders that are missed by other apps. • Detailed explanations of disorders integrate ABG, anion gap, and A-a gradient results providing individualized answers like no textbook can. • Refine your differential diagnosis even further with the included osmolal gap and urine anion gap calculators. • ABG Expert combines beauty and brains with optimization for iOS devices running iOS 13 and later. Disclaimer: Brian Dale Vander Werf MD Inc. has made every effort to ensure the accuracy of the information included in this product. However, the authors, developers, and Brian Dale Vander Werf MD Inc. are not responsible for errors or omissions or for any consequences from the use of this product and make no warranty, expressed or implied, with respect to the currency, completeness, or accuracy of the contents of this product. This product has been designed as a supplemental source of information for medical professionals. This product is not a substitute for clinical judgment, and the use of the information produced by this product in a particular situation remains the responsibility of the medical professional. Privacy Policy: This product does not collect, store, or transmit individually identifiable health information. References: NEJM. 2014; 371: 1434. Medicine. 1980; 59(3): 161. Kidney International. 2009; 76: 1239. Emerg Med. 1990; 19: 1310. Clin J Am Soc Nephrol. 2007; 2: 162. Nat Rev Nephrol. 2010; 6: 274. Anaesthesia. 2008; 63: 294. Clin J Am Soc Nephrol. 2012; 7: 671. The ICU Book. 3rd ed. Lippincott Williams & Wilkins; 2007.
OpenEvidence
This app provides healthcare professionals with evidence-based clinical decision support and medical information. It acts as a search engine, sourcing answers from peer-reviewed literature and leading medical organizations to aid in high-stakes medical decisions at the point of care.
- Clinical decision support
- Medical search engine
- Sourced from peer-reviewed literature
- FDA and CDC data integration
- Partnerships with leading medical journals
- Verified healthcare professional access
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Clinical Decision Support & Medical Search Engine for Healthcare Professionals (NPI Required) OpenEvidence is the most widely used clinical decision support platform and medical search engine among U.S. clinicians. According to independent studies, more American physicians use OpenEvidence than all other AI platforms combined. OpenEvidence is trusted by millions of verified healthcare professionals to make high-stakes clinical decisions at the point of care with answers that are sourced, cited, and grounded in peer-reviewed medical literature. Founded with the mission to organize and expand the world's collective medical knowledge, OpenEvidence is actively used daily by the majority of physicians in the United States. OpenEvidence is free for all verified U.S. clinicians. AN OFFICIAL AI PARTNER OF: The New England Journal of Medicine (NEJM) The Journal of the American Medical Association (JAMA) and its 11 specialty journals National Comprehensive Cancer Network (NCCN) Nature Cochrane Library Wiley WHAT YOU GET: • Specific answers to clinical questions, with every claim cited to its source • 35 million+ peer-reviewed papers, 300+ medical journals, plus FDA and CDC sources • Licensed full text from NEJM, JAMA, Nature, Cochrane, and others • EvidenceGrade™: see the strength of the evidence behind every answer • CME and MOC credits, earned by asking questions • Visits for ambient documentation, Dialer for secure patient calls, and Voice Mode for hands-free answers CONTENT AGREEMENTS AND COLLABORATIONS: American Academy of Family Physicians (AAFP) American College of Cardiology (ACC) American Diabetes Association (ADA) American Academy of Pediatrics (AAP) American College of Obstetricians and Gynecologists (ACOG) American College of Emergency Physicians (ACEP) ASCO Guidelines American Academy of Orthopaedic Surgeons (AAOS) American Academy of Ophthalmology (AAO) American Urological Association (AUA) Plus AAO-HNS, GINA, SNO, SSO, and more. IN USE ACROSS: 10,000+ hospitals and medical centers nationwide, including Mayo Clinic, Mount Sinai, Cedars-Sinai, MSKCC, and Sutter Health. WHY CLINICIANS TRUST US: • HIPAA compliant across the platform • NEJM, JAMA, Nature, and NCCN—official content partners • Tens of millions of clinical consultations per month WHAT CLINICIANS SAY: “OpenEvidence is currently the best AI tool for medical information.” — Dr. Paul Sax, Infectious Disease, Brigham and Women’s Hospital, Review in The New England Journal of Medicine Journal Watch (now NEJM Clinician) “In a morning report, a resident had a question that I didn’t know the answer to, but we were able to open OpenEvidence and get an answer on the spot.” — Dr. Kyle P. Lehenbauer, Minneapolis Veterans Affairs Medical Center “I use OpenEvidence multiple times during the day and every day. I am a better doc because of this. I expand my differential diagnoses and verify the science behind choices of treatments.” — Dr. Sharon E. Martin, Southern Huntingdon Medical Center Important note: OpenEvidence is available only to healthcare professionals. Users must verify their healthcare professional status before using OpenEvidence.
Screenshots
Verdict
The clearest difference is update cadence: OpenEvidence at weekly against ABG Expert's every 5 months. OpenEvidence also leads on ratings volume (12K vs 9) and chart position (#36 vs unranked). ABG Expert's advantage is review sentiment (100% vs 81%) and iOS requirement (13.0 vs 15.1). On price, rating, ads and in-app purchases 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
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
On the App Store both sit at effectively the same score — 4.8 for ABG Expert against 4.9 for OpenEvidence. That said, the two scores are not equally well evidenced: OpenEvidence has 12K ratings behind it against 9, so its average is the more settled of the two. Written reviews are what separate them: 100% of ABG Expert's written reviews are positive against 81% of OpenEvidence's.
ABG Expert ships an update every 5 months, OpenEvidence weekly. The most recent releases landed on October 20, 2026 and October 27, 2026 respectively.
| Parameter | ABG Expert | OpenEvidence |
|---|---|---|
| Price | Free | Free |
| Rating | 4.8 (9 ratings) | 4.9 (12K ratings) — better |
| Positive reviews | 100.0% of reviews — better | 81.0% of reviews |
| Number of ratings | 9 | 12K — better |
| Update frequency | Every 5 months | Weekly — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | Free |
| Best chart rank | — | #36 — better |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 13.0 — better | 15.1 |
| Further details — not scored | ||
| Size | 2 MB | 95 MB |
| Age rating | 12+ | +17 |
| Developer | Brian Dale Vander Werf MD Inc | OpenEvidence Inc. |
Customer experience
ABG Expert
OpenEvidence
Bugs and requests
ABG Expert
Not enough reviews yet to summarise bugs or requests.
OpenEvidence
Reported bugs
1 issue- App not working in latest update
Requested features
2 requests- Availability on MacBook
- Integration with clinical workflows and EMRs
In-app purchases
ABG Expert
No in-app purchases
OpenEvidence
No in-app purchases
Questions
Is ABG Expert free?
Is OpenEvidence free?
Which has better reviews, ABG Expert or OpenEvidence?
Do ABG Expert or OpenEvidence have ads?
Which is updated more often, ABG Expert or OpenEvidence?
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