Development of Marketplace Seller Rating System
Seller rating is one of the main trust signals for buyers. All else being equal, a product from a seller with a 4.8 out of 5 rating will sell better than the same product from a seller with 3.9. The system must be protected against manipulation, transparent, and reflect actual service quality.
Rating Components
Rating should not reduce to just review stars. A quality system accounts for several parameters:
| Parameter | Weight | Data Source |
|---|---|---|
| Average review rating | 40% | reviews table |
| Successful delivery rate | 20% | order_deliveries |
| Order processing speed | 15% | order_status_history |
| Cancellation rate by seller | 15% | order_cancellations |
| Return rate | 10% | returns |
Final rating is weighted sum of normalized indicators, converted to 1–5 scale.
Review Collection
Review can only be left after order delivery confirmation. This excludes reviews from non-buyers. Review form:
- Overall rating (1–5 stars)
- Parameter ratings: match description, packaging, shipping speed
- Text (optional, minimum length)
- Review photos (upload via S3)
Review reminder: push/email 3 days after delivery, repeat at 7 days.
Review Moderation
Reviews undergo automatic filtering (profanity, spam patterns) and can be disputed by seller. Seller can respond to any review — publicly visible to buyers, shows engagement.
Seller complaint about review goes to moderator. Removal grounds: review about different product, contains personal data, obvious fake.
Rating Recalculation
Rating not recalculated in real-time (expensive), but on schedule:
- Every hour for active sellers (>10 orders per 30 days)
- Daily for others
-- Aggregation for recalculation
SELECT
seller_id,
AVG(rating) as avg_rating,
COUNT(*) as reviews_count,
AVG(CASE WHEN status='delivered' THEN 1.0 ELSE 0.0 END) as delivery_rate
FROM orders
WHERE created_at >= now() - interval '90 days'
GROUP BY seller_id
Rating is rolling window: only last 90 days count. Protects against "stale" past and incentivizes maintaining quality.
Rating Display
On product page: stars + review count + link to seller storefront. On storefront: detailed breakdown by parameters, rating trend over 6 months (mini-chart), latest reviews.
Low Rating Consequences
- Rating < 4.0 — warning in account, products ranked lower
- Rating < 3.5 for 30 days — restrict new orders, notify support team
- Rating < 3.0 — automatic account suspension pending review
Motivates sellers to improve rather than operate with poor rating for years.
Development timeline: 3–4 weeks for complete system with multi-factor rating, review moderation, and automatic consequences.