Guide chapters
§ - Important Disclaimer Regarding the Nature of the Material00 - How to use the guide01 - First choose the business and responsibility model, then build the marketplace02 - Construction plan: what must exist and when03 - Responsibility Matrix: Operator, Seller, and Suppliers04 - Seller Onboarding: Whom to Allow to Sell05 - Product card: information without which an offer cannot be published06 - GPSR: Product Safety in Practice07 - Product Category Gates08 - Packaging and EPR: who is actually responsible09 - Consumer Law: Sale, Withdrawal, and Complaint10 - Prices, Promotions, Ranking, Advertising, and Reviews11 - Payments, Payouts, VAT, and Sales Documents12 - GDPR without myths: what to record, where, and on what basis13 - DSA: reporting, moderation, and seller traceability14 - P2B: fair rules for business users15 - DAC7: seller data and annual reporting16 - E-commerce accessibility from June 28, 202517 - Cybersecurity and NIS218 - Retention: How long to store data and evidence19 - Post-launch operations: calendar and owners20 - Four business models - specific decisions21 - Document and Procedure Package to Prepare22 - GO / NO-GO Checklist Before Launch23 - Most Common Misconceptions24 - Sources and Update Principle

Prices, Promotions, Ranking, Advertising, and Reviews

Lowest Price from 30 Days#

When a seller communicates a price reduction - a crossed-out price, a percentage, the phrase "promotion," "cheaper," or an equivalent message - the lowest price applied in the 30 days prior to the reduction is displayed next to the current price. If the product has been offered for less than 30 days, the lowest price since the start of the offer is displayed. A special rule applies to perishable goods.

The platform must:

  • store the price history for each offer and variant;
  • calculate the period based on the price actually offered to consumers, not the supplier's catalog price;
  • display the information in the same location and for the same variant as the promotion;
  • update it consistently on the list, product page, in the cart, at checkout, and in internal advertising;
  • block manual entry of a more favorable "30-day price" by the seller;
  • retain proof of calculation.

Ranking and Paid Visibility#

In search results or in an easily accessible explanation, the platform provides the main parameters determining the order and their relative importance. It does not disclose the algorithm or security measures but explains the actual factors, e.g., relevance, price, availability, delivery time, service quality, popularity, and paid promotion.

Any paid increase in visibility is clearly marked as advertising/sponsored offer. If the operator sells their own goods or favors a partner, they describe this in the seller terms and conditions and in the ranking information.

Reviews#

The platform publishes information on whether and how it verifies that a review comes from a person who purchased or used the product. It then acts precisely according to this declaration.

  • The "verified purchase" label is awarded exclusively to reviews linked to a genuinely completed order.
  • Unverified reviews may be allowed but are marked differently.
  • Purchased, generated, duplicated, or manipulated reviews are prohibited, as is the selective publication of only positive ones without disclosing the rules.
  • Moderation of offensive content or personal data must not remove fair criticism simply because it is negative.
  • A seller cannot make benefits conditional on leaving a positive review.
  • The platform stores the reason for moderation and allows for appeals to the required extent.

Personalized Pricing#

If the price has been individually adjusted based on automated decision-making, the consumer receives clear information before purchase. General segmentation and coupons with fixed rules are not always personalized pricing; however, the platform must describe the mechanism and obtain a GDPR assessment if it uses profiling.

Basis and sources: UOKiK (Poland) - Omnibus Changes for Platforms; UOKiK (Poland) - Pricing and Information Obligations in E-commerce; UOKiK (Poland) - Penalties for Incorrect Lowest Price, 2026.

Need to implement these processes in a real marketplace?

I design multi-vendor platforms with onboarding, payments, moderation, and operational workflows.

Explore marketplace development