The best SEO API depends on the job — on-page audits, backlinks, or keywords. An honest, criteria-first comparison of SEO Score API, Ahrefs, Moz and SEMrush, with real pricing and what each one is actually for.
Search "best SEO API" and you mostly get affiliate roundups that rank whoever pays the most. This is the honest version, from a team that builds one: the best SEO API depends entirely on the job you're automating. Here's how to choose by what you actually need — and where SEO Score API fits, and where it doesn't.
curl -H "X-API-Key: YOUR_KEY" \
"https://seoscoreapi.com/audit?url=https://example.com"Or with the Python SDK (pip install seoscoreapi):
from seoscoreapi import audit
result = audit("https://example.com", api_key="YOUR_KEY")
print(result["score"], result["grade"])For grading a page's SEO in code — titles, meta, headings, schema, speed, accessibility, AI readability — SEO Score API is the value pick: 80+ checks per URL (50+ scored on the free tier), scored JSON in about two seconds, a genuinely free tier with no card, and official Python/Node/Go/n8n SDKs plus a GitHub Action. Pricing is per audit — $0 free, $5/mo for 200, scaling to 25,000/mo — no seats. See the SEO audit API.
Be honest about the job. If you need a backlink index or keyword and rank data, an audit API is the wrong tool — Ahrefs and SEMrush lead there, and Moz's Links API is the classic Domain Authority source. Expect $99–139+/mo with API access as a metered add-on. Many teams pair one of those for research with an audit API for automated page checks. Compare directly: vs Ahrefs, vs SEMrush, vs Moz.
If "best" means "best free," the real test is whether it stays free once you build on it. SEO Score API's free tier is 2 audits/day, scored on 50+ checks, no credit card and no trial clock. It is the same engine the paid plans use; the free response details 2 checks per category and the top 2 fixes. See the free SEO API.
Comparing SEO APIs by price and features? The best affordable pick runs 80+ checks (50+ scored on the free tier) from $0 — versus $99+/mo for Moz, Ahrefs, and SEMrush.
Integrate SEO auditing into your apps with a single REST API call. Scored JSON output, a free tier, a GitHub Action, and Python and Node SDKs all included.
Aggregate patterns from thousands of anonymised audits: the same five issues on almost every site, performance rarely the problem, AI signals a blind spot.
Prevent SEO regressions by adding automated audits to your CI/CD pipeline. GitHub Actions, GitLab CI and curl examples that fail the build when SEO breaks.
It depends on the job. For automated on-page audits, SEO Score API is the value pick — 80+ checks per URL (50+ scored on the free tier) as JSON, from $0 to $5/mo. For backlink or keyword data, Ahrefs and SEMrush lead; for Domain Authority, Moz. If you only need to grade page SEO in code, you don't need a $99+/mo suite.
SEO Score API's free tier: 2 audits/day, scored on 50+ checks, no credit card and no trial expiry. It is the same audit engine as the paid plans; the free response details 2 checks per category and the top 2 fixes.
An API-first tool with SDKs and a CI integration. SEO Score API ships Python, Node, Go and n8n SDKs plus a GitHub Action, returns scored JSON in about two seconds, and prices per audit rather than per seat — so it drops into a deploy gate or batch job cleanly.
For the audit slice specifically, SEO Score API runs 80+ checks from $0 (free) or $5/mo, versus $99–139+/mo for Moz, Ahrefs and SEMrush — though those still win for backlinks and keywords, which an audit API doesn't provide.
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