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International contributions in US dollars (USD).
Support with PayPal (new tab)RobMac Software · Voluntary support
Support development.
If Engineering Toolkit is useful to you, you can voluntarily support its continued development and maintenance.
Engineering Toolkit is free forever. All functionality remains available whether or not you contribute. No subscriptions, premium features, paid calculators or advertising.
Contributions provide no additional functionality, privileges, digital goods or services, exclusive content or rewards.
Your privacy when contributing
This page has no payment forms, user accounts, advertising, analytics or tracking tools. It does not collect card details or embed payment processing. Links contain no tracking parameters.
When you visit this page, your browser and GitHub Pages, the hosting service, may process network information such as your IP address. When you follow a payment link, the provider may process personal, financial and transaction information under its own terms and privacy policy. Review those documents on the provider’s website before continuing.
RobMac Software may receive transaction and contributor information through its merchant accounts, outside Engineering Toolkit. Deleting local app data does not delete external payment records.
RobMac Software will use merchant information only to administer contributions, handle payment-related inquiries or incidents, and meet applicable legal and tax obligations. RobMac Software will not collect unnecessary personal information, sell personal information, use contributor data for advertising, or create contributor profiles for commercial targeting. The owner intends to minimize unnecessary copies of merchant records and restrict access.
These commitments apply to processing controlled by RobMac Software. They do not govern payment providers, browsers, operating systems or hosting services. Legal and tax requirements may require records to be retained; no fixed retention period or automatic deletion of external records is promised.
Provider privacy references: PayPal privacy notice (Mexico reference) and Mercado Pago privacy declaration (Mexico reference). These are references from the providers’ Mexico sites. Country-specific notices or additional terms may apply to your checkout, particularly for international contributors. Review the applicable notice presented by your selected provider before entering information.
Read the Engineering Toolkit Privacy Policy for the app’s data practices. For questions about contribution privacy, contact robmacsoftware@gmail.com.