If you source links from both ereferer.com and serpzilla.com, one number decides how much you overwrite yourself: how much do their site databases overlap? We matched both catalogs on the normalized domain (lowercased, no scheme or www) inside our Backlink Pricing dataset.
The overlap
The two databases share 24,673 domains — 35% of ereferer.com and 19% of serpzilla.com. As a Jaccard index (shared ÷ combined) the catalogs are 14% identical, so about 86% of the combined pool is exclusive to one side.
Unique inventory
- 46,816 domains on ereferer.com only (65% of its catalog).
- 106,848 domains on serpzilla.com only (81% of its catalog).
Where they overlap, who's cheaper?
For the 24,673 shared domains priced on both platforms, comparing the cheapest listing on each:
On identical inventory, ereferer.com is the cheaper source 74% of the time (median $80 vs $183 for the same sites). The average absolute price gap per shared domain is $163 — always price-check a placement across platforms before buying.
Quality (Domain Rating)
| DR band | On both | ereferer.com only | serpzilla.com only |
|---|---|---|---|
| DR 80–100 | 0% | 1% | 1% |
| DR 60–79 | 5% | 3% | 4% |
| DR 40–59 | 16% | 7% | 14% |
| DR 20–39 | 35% | 22% | 26% |
| DR 0–19 | 44% | 68% | 56% |
Median DR: 24 shared, 10 ereferer.com-exclusive, 15 serpzilla.com-exclusive.
Geography
| # | ereferer.com | domains | serpzilla.com | domains |
|---|---|---|---|---|
| 1 | France | 18,676 | United States | 14,578 |
| 2 | United States | 5,049 | France | 6,720 |
| 3 | India | 2,668 | Russia | 5,564 |
| 4 | Italy | 1,940 | India | 5,431 |
| 5 | Spain | 1,705 | Germany | 4,113 |
| 6 | Germany | 1,387 | Italy | 3,247 |
FAQ
Does "on both" mean the same seller?
Not necessarily — a domain can be listed on both marketplaces by the same publisher or different resellers. What's shared is the placement opportunity, which is what you dedupe before buying.
Is a bigger database always better?
No. Overlap, price spread, DR/traffic quality and geography decide value for a specific campaign. Comparing databases is how you buy the same link for less and find inventory a single platform can't offer.