The checklist
What a complete SEO API needs
- An authority score — Domain Rating (0–100) + Ahrefs Rank, via the Ahrefs API
- Two traffic estimates — Similarweb-style total visits and Ahrefs organic, cross-checkable in one response
- Audience context — engagement, channel mix, top countries, popularity ranks
- Keyword numbers — volume, difficulty, CPC with currency
- SERP & index checks — positions per query, presence in Google
- Provenance — provider + fetch date on every field,
null never faked as zero
We serve all six. One key, one envelope, one documented contract.
| SEO Metrics API | Similarweb | Ahrefs | Semrush |
|---|
| Entry price | $0 · paid from $20/mo | $149/mo | $129/mo | $139.95/mo |
| API included at entry | Yes — every tier | No — separate sales process | No — higher tiers | No — Business ($449.95/mo) |
| Authority + traffic + keywords in one call/key | Yes | Traffic focus | Authority/organic focus | Broad, but unit-metered |
Published entry list prices as of August 2026; check each vendor's site for current figures. Each of those platforms does far more than serve metrics — this comparison is strictly about getting numbers by API.
The per-credit math
Starter is $20 for 20,000 credits — $0.001 per credit, where a credit is
one call we pay a data provider for. A domain lookup spends one credit per field group it
fetches fresh (1 for fields=rating, 4 for the default scope), so a full
profile costs about four tenths of a cent. Anything answered from cache costs nothing at
all, and popular domains are usually cached, so real-world cost per lookup lands below
the list rate. Growth works out to ~$0.00084 and Scale to ~$0.00086 per credit, with the
bigger plans buying rate (300–600 requests a minute) as much as volume. There is no overage billing to be surprised by: an
exhausted quota answers 429 quota_exceeded until you upgrade or the
month resets.
$ curl -H "Authorization: Bearer $KEY" \
"https://seometricsapi.com/v1/domains/shopify.com?fields=rating,traffic,countries"
{
"data": {
"domain": "shopify.com",
"domain_rating": 96,
"monthly_visits": 68900000,
"organic_monthly_visits": 31200000,
"top_countries": [ { "country_code": "US", "share": 0.34 } ],
"sources": { "domain_rating": { "provider": "ahrefs", "status": "ok" } }
},
"meta": { "cache": "hit", "cost_units": 0 },
"error": null
}