PeakD4Y vs Machaon
Price, ratings, monetisation and update history for both apps, side by side ā with what reviewers say about each.
PeakD4Y
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SUBST4NCE is an educational harm reduction reference app providing research-backed pharmacokinetic data and drug interaction warnings. IMPORTANT DISCLAIMER This app is NOT a medical device and does NOT provide medical advice. It is a visualization and reference tool for educational purposes only. Always consult healthcare professionals for medical decisions. WHAT'S INSIDE Comprehensive Substance Database ⢠80+ substances across multiple categories ⢠Published pharmacokinetic data (half-lives, metabolism pathways) ⢠Mechanism of action explanations ⢠Data quality indicators showing research confidence levels Interaction Checker ⢠Check combinations of multiple substances ⢠Understand potential interaction mechanisms ⢠Color-coded risk levels based on published research ⢠Plain-language explanations of why interactions matter Visual Timeline ⢠See pharmacokinetic curves for substances ⢠Understand onset, peak, and duration patterns ⢠Multi-substance overlay visualization ⢠Body load indicators Personal Context (Optional) ⢠Add your biological factors for educational context ⢠Weight, metabolism, and health considerations ⢠Tolerance tracking ⢠Current medications reference Research Citations ⢠Every data point linked to published sources ⢠PubMed IDs and DOIs for verification ⢠FDA and WHO reference data ⢠"Limited data" warnings for research chemicals CATEGORIES COVERED ⢠Alcohol & Cannabinoids ⢠Stimulants & Depressants ⢠Psychedelics & Dissociatives ⢠Prescription medications ⢠Research chemicals (with appropriate warnings) ⢠And more... SAFETY FEATURES ⢠Emergency resources always accessible ⢠SAMHSA helpline integration ⢠Non-judgmental, educational framing ⢠Privacy-first: all data stored locally on your device DESIGNED FOR ⢠Harm reduction education ⢠Healthcare students and professionals ⢠Researchers and educators ⢠Anyone seeking evidence-based substance information This app does NOT: ⢠Provide dosing recommendations ⢠Calculate "safe" times to drive ⢠Facilitate procurement ⢠Replace professional medical advice All information is compiled from peer-reviewed research and official sources. Users accept full responsibility for how they use this educational reference. 18+ only. By using this app, you acknowledge the terms and conditions presented at first launch. Questions or feedback? Contact us through the support link.
Machaon
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Healstack is a personal substance tracker, harm reduction wiki, and health dashboard. Log doses with a journal you can filter and search, browse a 200+ substance wiki with harm reduction data, and see your health trends in one dashboard. Your data stays in your account ā no ads, no data sales. FEATURES - Dose logging with journal, filters, and search - 200+ substance wiki with harm reduction information - Health dashboard with trends over time - Private by design Healstack is built for harm reduction: honest information and personal tracking to help you make safer choices.
Screenshots
Verdict
PeakD4Y and Machaon are too close to call on the numbers: across 3 compared parameters ā price, in-app purchases and iOS requirement among them ā neither pulls far enough ahead to decide it. What separates them is feature set and interface, not measurable difference.
Scored on Price Ā· Rating Ā· Positive reviews Ā· Number of ratings Ā· Update frequency Ā· Ads Ā· In-app purchases Ā· Monetization Ā· Best chart rank Ā· Devices Ā· Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
| Parameter | PeakD4Y | Machaon |
|---|---|---|
| Price | Free | Free |
| Update frequency | ā | Every 3 weeks |
| Ads | ā | No |
| In-app purchases | No | No |
| Devices | ā | iPhone ā better |
| Requires iOS | 17.0 | 17.0 |
| Further details ā not scored | ||
| Size | 3 MB | 5 MB |
| Age rating | 17+ | 12+ |
| Developer | Kevin Kulcsar | Joshua Trommel |
In-app purchases
PeakD4Y
No in-app purchases
Machaon
No in-app purchases









