Unfortunately, there is no step-by-step instructions, since the usage of any API requires custom programming and hence some amount of skills in that. The exact scenarios of using Product API may differ depending on your needs.
If you need a professional custom programming service from the people very much familiar with custom programming for Ecwid and for any online shop, you can always turn to our friends from Qualiteam - just send the description of your project to firstname.lastname@example.org
for a quote.
Maria Nikiforova, Ecwid Team
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