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Verified July 29, 2026 · Maintained by usecos.app Research & Engineering
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usecos.app is a Canadian calculator website for mortgage, salary, GST/HST, rental-investor, and VIN research. The goal is fewer, stronger tools: visible formulas, dated source checks, original comparison data where useful, and no accounts or calculator-input collection. usecos.app is a Canadian calculator website and is not associated with usecos.com or any online retail store.
Mortgage pages use Canadian mortgage math and link to source notes for OSFI stress-test context, CMHC insurance assumptions, and Interest Act compounding conventions. Salary and GST/HST pages use shared tax-data files checked against official federal, provincial, and Revenu Quebec sources. VIN pages validate the 17-character format and use NHTSA data for US decode and recall lookups.
Each major calculator links to a methodology block, source list, and related guide or data report so users and search engines can see what was included, what was excluded, and when the page was last checked.
Calculator inputs run in the browser. usecos.app does not require an account, does not show ads, does not use tracking cookies, and does not store mortgage, salary, GST, rental-property, or VIN lookup history on a usecos.app account. Recent values and preferences may be stored locally on your device for convenience.
For the VIN recall feature, the VIN you submit is sent to the NHTSA API because recall data comes from NHTSA. The privacy policy explains that exception in plain language.
Explore the complete directory on our All Tools Hub.
usecos.app pages are written and maintained by usecos.app Research & Engineering. Financial and procedural pages follow our written Editorial & Fact-Checking Policy and zero-server-upload Security Architecture. Detailed formulas and validation benchmarks are documented in our methodology hub.
usecos.app Research & Engineering maintains the site with a software-development focus on transparent calculation tools, source-backed data, test coverage, and practical user workflows. The pages can explain how formulas are sourced, implemented, tested, and limited.
usecos.app Research & Engineering is not presented as a mortgage broker, financial planner, accountant, lawyer, lender, insurer, or vehicle-history provider. Mortgage approval, tax filing, legal interpretation, insurance, liens, and full vehicle-history decisions require qualified professionals or official providers. See the public author profile.
If a source rate, formula, date, calculator result, or page claim looks wrong, send the URL and expected correction through contact. Calculator outputs are estimates only; the disclaimer explains the limits.