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Feature checklists make every tool look equivalent. This table leads with the three things that actually differ — what it costs you before it works, whether your files leave your device, and where the free version stops.
| Sleep Foundationsleepfoundation.org | MedlinePlusmedlineplus.gov | Omni Calculatoromnicalculator.com | Drugs.com Interaction Checkerdrugs.com | |
|---|---|---|---|---|
| What it does | Explains sleep with a medical review panel, plus bedtime and cycle calculators | Plain-language health information from the US National Library of Medicine | Around 3,000 small calculators, each with the formula shown underneath | Lists the interactions between the medicines, supplements and alcohol you enter |
| What it costs you | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. | No sign-upWorks the moment the page loads. No account, no email, no trial. |
| Your files | Runs on their server | Runs on their server | Runs on their server | Runs on their server |
| Where it stops | It is general education, not medical advice — persistent sleep problems need a clinician, and the site funds itself partly through mattress reviews. | It is US-oriented reference material and deliberately general — it does not diagnose, and it is no substitute for seeing a clinician. | Health calculators here are population-level estimates with wide error bars — useful for orientation, not for a decision about treatment. | It cannot see your dose, your kidney function or your other conditions, so it flags possibilities for a pharmacist or doctor to judge — never stop or change a medicine on its say-so. |
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| Category | Health & Everyday Life | Health & Everyday Life | Health & Everyday Life | Health & Everyday Life |
| Last checked | 2026-07-29 | 2026-07-29 | 2026-07-29 | 2026-07-29 |
| Open the site | Open | Open | Open | Open |
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