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Not sure where to start? Assess first.

Four honest checks for your skin and your routine, in one place — with a plain guide to which one you actually need. Each one runs in your browser and keeps your answers on your device.

See the four checks → Which one do I need?

Four ways to read your skin.

Each check answers one clear question. Pick the one that matches what you are trying to work out — or start with the Stack Audit if you just want the whole picture.

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Stack Audit

Scores your whole routine out of 100 across compatibility, efficiency, barrier load and coverage. Flags conflicts and redundancies, names coverage gaps, and tells you exactly what to cut or add — with a working AM/PM schedule.

Best when: you have two or more products and want to know whether the routine works as a whole.

Run the audit →
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Barrier Health Assessment

Twenty evidence-based questions about your skin, habits and routine produce a scored barrier-health report and personalised repair steps — so you can tell a genuinely compromised barrier from ordinary dryness.

Best when: your skin feels tight, stings on application, flakes, or reacts to things it used to tolerate.

Assess my barrier →
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Fungal Acne Safe Checker

Paste any product's ingredient list and instantly see whether it is fungal-acne (malassezia) safe. Flags the fatty acids, esters and oils that commonly feed a flare, ingredient by ingredient.

Best when: you get small, uniform bumps that ordinary acne treatment does not clear.

Check a product →
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Diagnose a Reaction

Describe what you are seeing and what you have been using. Skin Stacker cross-references the actives in your routine and ranks the most likely causes — purging, irritation, allergy, fungal flare, a true breakout, or something a dermatologist should see.

Best when: something flared recently and you need to find the culprit.

Diagnose it →

Still deciding? Match the question.

Questions.

Which assessment should I start with?
Start from the problem, not the tool. To know whether your whole routine works together, run the Stack Audit. If your skin feels tight, stings, or flakes and you suspect it is compromised, take the Barrier Health Assessment. If you get small uniform bumps that ordinary acne treatment does not fix, use the Fungal Acne Safe Checker. If something flared recently and you need to find the culprit, use Diagnose a Reaction. When in doubt, the Stack Audit is the best all-round starting point.
What is the difference between the Stack Audit and Diagnose a Reaction?
The Stack Audit looks at your routine as a whole and scores how well it works — conflicts, redundancies, coverage gaps and barrier load — whether or not anything is wrong right now. Diagnose a Reaction is for when something has already gone wrong: it asks what you are seeing and what you have been using, then ranks the most likely causes, from purging and irritation to allergy, fungal flare, or a problem that needs a dermatologist.
Do I need an account or login to use these?
No. Skin Stacker has no login. Every assessment runs in your browser, and anything you save — your skin profile, routines, results — lives only in your device's local storage, never on a server. Close the tab and nothing leaves your device.
Are these assessments a substitute for a dermatologist?
No. They are educational tools that catch common patterns — ingredient conflicts, barrier stress, fungal-acne triggers, likely reaction causes — but they cannot examine your skin or diagnose a medical condition. For anything persistent, painful, spreading, or worrying, see a qualified dermatologist.
Does Skin Stacker make money from what these tools recommend?
No. There are no ads, no affiliate links, and no paid placement anywhere on Skin Stacker. The assessments recommend what the evidence supports, and the results would read exactly the same if no brand existed. That independence is the whole point of the site.

Written and maintained by JoAnn, founder and editor of Skin Stacker. Reviewed / Last updated: 2026-07-20.

No ads, no affiliates, no paid placement — ever.