Get an audit

Head to head · Keyword data · October 2026 research run

Majestic API vs Similarweb

Similarweb scores 46 (D) on agent readiness against Majestic API's 33.4 (F), and leads in 6 of 7 scored categories. Majestic API leads on payments & pricing. Both do keyword data.

Best SEO and search visibility data for AI agents · All 45 seo comparisons

Majestic APIMajestic (Majestic-12 Limited) · HTTP API F33.4/100#937 of 950 SimilarwebSimilarweb Ltd. · HTTP API D46/100#858 of 950

Which one, for what

Majestic API F

Good for An agent that needs backlink, referring domain, anchor text and Trust Flow data in volume for an owner who already pays for the API plan.

Ahead on

  • Payments & pricing, 15 against 5

Watch for

Clause 14.1(f) of the supply terms forbids querying Majestic's database or servers with automated tools without prior permission. This matters before any probe is run

Similarweb D

Good for Traffic and engagement estimates, traffic channel mix and keyword click data for domains an agent doesn't own, with app, company and retail data on the same key.

Ahead on

  • Reliability, 35 against 17
  • Schema & documentation, 63 against 44
  • Agent ergonomics, 67 against 54
  • Security & auth, 52 against 32
  • Maintenance & community, 33 against 22
  • Transparency & trust, 60 against 53

Watch for

API and MCP access need a Business, Enterprise or API-only plan bought through sales. The FAQ says there's no API test without a subscription

Score by category

CategoryWeight this runMajestic APISimilarwebEdge
Reliability16%201735Similarweb +18
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.24463Similarweb +19
Agent ergonomics13%16.25467Similarweb +13
Security & auth14%17.53252Similarweb +20
Payments & pricing10%12.5155Majestic API +10
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.82233Similarweb +11
Transparency & trust7%8.85360Similarweb +7
Negative events≤1500
Total33.4 · F46 · D

Facts side by side

FactMajestic APISimilarweb
KindHTTP APIHTTP API
VendorMajestic (Majestic-12 Limited)Similarweb Ltd.
Hosted endpointhttps://api.majestic.comhttps://api.similarweb.com
TransportsHTTPHTTP
AuthAPI keyOAuth or key
PricingPaidPaid
x402nono
LicenceProprietary service under Majestic's Terms and Conditions. The Python 3 connector on GitHub carries a BSD-style licence fileProprietary service under Similarweb's terms of use
Read-only variant documentednono
llms.txtyesyes
Last releasenone2026-09-24
Terms last updatedno date given2025-03-19
Privacy policy last updated2026-04-012026-06-30
Customer content may train modelsnot found in the textnot found in the text
Terms restrict automated accessyesyes
Terms restrict benchmarkingnot found in the textyes
Terms or service can change without noticeyesnot found in the text
Arbitration or class-action waivernot found in the textnot found in the text
Popularity3 starsnone

Verdicts

Majestic API

Each command's cost in units is published and a sandbox endpoint returns sample data without spending allowance. API access starts at $399.99 a month with no trial, and no OpenAPI file, status page, numeric rate limit, SLA or API changelog was found. The supply terms require permission before querying with automated tools.

Similarweb

The V5 API returns traffic estimates, keyword clicks and SERP positions with selectable metrics, and the hosted MCP server accepts OAuth with a read scope. Access needs a Business, Enterprise or API-only subscription sold through sales, with no API trial, public price per credit or public status page found.

Before you call either

Majestic API

  1. Send requests by HTTPS POST with app_api_key in the body. The docs show GET URLs for demonstration only and plain HTTP still works
  2. Always set datasource=fresh or datasource=historic. Without it the Historic Index is used when the plan includes it
  3. Call GetSubscriptionInfo (no cost) before a large pull. GetBackLinkData spends 5,000 analysis units a call plus one retrieval unit a row
  4. Read columns by header name, not position. The docs say column order can change between requests and Majestic may vary rows and columns at any time
  5. Develop against https://developer.majestic.com/api/json, which costs no units, then switch the host to api.majestic.com
  6. Ask the owner to confirm Majestic's permission for automated querying first. Clause 14.1(f) of the terms requires it

Similarweb

  1. Send the key in the api-key header. The capabilities endpoint documents ?api_key= in the URL, which puts the secret in logs
  2. Stay under 10 requests a second. A 429 can also mean the monthly credit allowance is spent, so call /capabilities (free) before retrying
  3. Pass domains in lower case without www. or a path. The docs list 401 as data not found for a malformed domain
  4. Request only the metrics, countries and months needed. Credits multiply across domains, metrics, countries and periods, and daily granularity costs about 30 times monthly
  5. Website keywords accept monthly granularity for the last three months only, and position isn't returned for worldwide

Questions

Which is better for AI agents, Majestic API or Similarweb?

Similarweb scores 46 (D) on agent readiness against Majestic API's 33.4 (F), and leads in 6 of 7 scored categories. Majestic API leads on payments & pricing.

Do Majestic API and Similarweb need an API key?

Majestic API needs an API key. Similarweb takes an API key or an OAuth sign-in.

Can an agent call Majestic API and Similarweb without installing anything?

Yes. Majestic API has a hosted endpoint at https://api.majestic.com and Similarweb at https://api.similarweb.com.

Other comparisons with Majestic API or Similarweb

Machine-readable

For companies

Do agents find, use and choose your tools?

An agent-readiness audit runs our probes, task suite and eight reviewer agents against your public and internal tools, and comes back with a scorecard, the transcripts of what failed, and a fix list in priority order. From $2,500, re-run included. We never take payment to move a rank. We do help companies earn one.

Get an auditSee a sample report