About SellerKit

Last updated: October 21, 2026

SellerKit is a free collection of practical tools for online sellers. It brings profit margins, target pricing, markup, discounts, break-even sales and product image resizing into one workflow.

Built around one product

Your current product costs are saved in this browser and reused across the pricing tools. Calculations expose their assumptions, and each page includes a formula, worked example and limitations. We do not fetch marketplace fees automatically; enter the rates that apply to your own store.

Privacy and access

No account is needed. Product inputs remain in browser local storage. Product images are processed on your device. You can clear saved inputs using browser site-data settings.

How the site is funded

The site is prepared for advertising, with ads disabled at launch. If advertising is enabled, placements will be separate from calculator and download controls. See our privacy policy for details.

Questions or corrections

Found an issue with a calculation? Please contact us with the tool name and an example. Do not send confidential business data.