Head to head · Seo traffic · October 2026 research run

Similarweb vs SpyFu API

SpyFu API scores 48.1 (D) on agent readiness against Similarweb's 47 (D), and leads in 3 of 7 scored categories. Similarweb leads on maintenance & community and transparency & trust. Both do seo traffic.

Best SEO and search visibility data for AI agents · All 56 seo comparisons

Which one, for what

Similarweb D

Best 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

  • Maintenance & community, 43 against 16
  • Transparency & trust, 62 against 38

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

SpyFu API D

Best for Competitor keyword, ad history and ranking history research, with a long paid-search archive.

Ahead on

  • Reliability, 45 against 35
  • Schema & documentation, 75 against 63
  • Payments & pricing, 20 against 5

Watch for

API access needs a paid Pro + AI or Team plan; there is no free tier

Why the edge

Each category where one leads by five points or more, with the reason behind each side's score from its assessment. The numbers are in the table below; this is what they stand for.

Maintenance & community Similarweb +27

Similarweb 43

Per the 8 October check, not re-read on 5 November, since Similarweb's terms bar robots, spiders, scrapers and other automated means on its Site, Platform and Applications. The newest dated API change on record is the deprecation of the legacy REST endpoints on 6 October 2026, in the migration guide, 30 days before 5 November and so within 30 days (30). The V5 docs' 24 September publish date records no change and no longer counts. Three dated entries in 90 days not established, because the V5 changelog didn't load (0). Two public changelogs and a help centre with ticket support (8 of 15). No official SDKs, and no registry entry we could read (0). The hosted MCP server and both docs sites were live and current (5 of 10). Total 43.

SpyFu API 16

Closed service. No changelog. The newest dated docs change found is 13 July 2026 (the rate-limits and pricing pages' updatedAt), 116 days before this check (10). Reference pages are dated between August 2025 and 9 July 2026, so fewer than three dated changes in 90 days (0). A help centre and support email, with no public changelog or tracker (6 of 15). No official SDK (0). No package to judge (0). 10+0+6+0+0 = 16.

Transparency & trust Similarweb +24

Similarweb 62

Per the 8 October check, not re-read on 5 November, since Similarweb's terms bar robots, spiders, scrapers and other automated means on its Site, Platform and Applications. Closed service under public terms last updated 19 March 2025 (15 of 30). The privacy policy, amended 30 June 2026, states retention as long as reasonably necessary with no periods, and no public DPA was found (12 of 30). Deprecations carry dates, such as Demographics 1.0 on 1 January 2025 and legacy REST endpoints on 6 October 2026 with a mapping table, but no written notice policy was found (12 of 20). The privacy policy says servers are in the United States, and no sub-processor list was found on the public pages (6 of 20). Total 45.

SpyFu API 38

Closed service under terms naming SpyFu, Inc., updated 25 February 2019, under Arizona law (15 of 30). The privacy policy carries no date, retention periods, controller or named processors, and says data is moved to the United States (5 of 30). No deprecation policy or notices found (0 of 20). No subprocessors named; data location is the United States (3 of 20). 15+5+0+3 = 23.

Payments & pricing SpyFu API +15

Similarweb 5

Per the 8 October check, not re-read on 5 November, since Similarweb's terms bar robots, spiders, scrapers and other automated means on its Site, Platform and Applications. No x402, MPP or L402 found (0). No price per credit or API plan price is public. The credit cost per endpoint and the formula are published, which earns 5 of 20 as a departure from the checklist. No free tier or API trial, since the FAQ requires an active subscription (0). A person has to buy through sales and an admin has to create the key (0). Total 5.

SpyFu API 20

No x402, MPP or L402 (0). Per-row prices for every endpoint are public on the developer site (20). No free tier: access needs a paid Pro + AI or Team plan, and plan prices sit on a pricing page that answered 403 (0). A person signs up and pays in a browser (0). 0+20+0+0 = 20.

Schema & documentation SpyFu API +12

Similarweb 63

Per the 8 October check, not re-read on 5 November, since Similarweb's terms bar robots, spiders, scrapers and other automated means on its Site, Platform and Applications. No public OpenAPI file found. Reference pages carry structured parameter and response definitions in Markdown, and the MCP tool schemas need a key to read (8 of 25). llms.txt on both docs sites with Markdown pages (10). Endpoint pages state purpose, output fields, constraints and credit cost, with little on when not to use one (12 of 20). Parameters are typed with enums for granularity and device, and defaults are stated (12 of 15). Request and response examples exist, and the error table has mismatched descriptions for codes 101 and 102 (9 of 15). Versioned paths and two changelogs, the newer one unreadable to us (12 of 15). Total 63.

SpyFu API 75

Every reference page embeds an OpenAPI 3.1 definition with security schemes and responses, but no single downloadable file is linked (20 of 25). llms.txt and a Markdown twin of every page (10). Descriptions say what each endpoint returns and how it differs from its neighbours ('unlike term-based endpoints...') (17 of 20). Typed parameters with descriptions, examples and required flags (12 of 15). 200, 400, 401 and 500 in the definitions and a 429 example, little on error bodies (11 of 15). v2 in every path, but no changelog (/changelog answered 404) (5 of 15). 20+10+17+12+11+5 = 75.

Reliability SpyFu API +10

Similarweb 35

Graded as a hosted service, on the V5 REST API and the hosted MCP server. No public status page found. similarweb.statuspage.io still redirects to a Statuspage Google sign-in on 5 November (0). No readable incident history (5). Per the 8 October check, not re-read on 5 November, since Similarweb's terms bar robots, spiders, scrapers and other automated means on its Site, Platform and Applications. Rate limits published, 10 requests a second for REST and 20 pending requests for Batch (15). 429 is documented with advice to add a rate limiter and errors aren't charged, but no Retry-After or backoff guidance was found, and Batch has a retry endpoint (5 of 15). The SLA page is dated January 2016 and its PDF returns 404 (0). V5 is announced as live and carries no beta label (10). Total 35.

SpyFu API 45

Hosted lines. No status page found; status.spyfu.com did not resolve and the docs link none (0). No incident history to read (5). Per-endpoint limits published, 10 to 1,000 requests a second over a rolling second (15). 429 with Retry-After: 1 and a JSON error body, and every endpoint is a read (15). No SLA found (0). Generally available (10). 0+5+15+15+0+10 = 45.

Score by category

CategoryWeight this runSimilarwebSpyFu APIEdge
Reliability16%203545SpyFu API +10
Performance10%pendingpendingpendingnot scored in this run
Schema & documentation13%16.26375SpyFu API +12
Agent ergonomics13%16.26765Similarweb +2
Security & auth14%17.55252even
Payments & pricing10%12.5520SpyFu API +15
Task success10%pendingpendingpendingnot scored in this run
Maintenance & community7%8.84316Similarweb +27
Transparency & trust7%8.86238Similarweb +24
Negative events≤1500
TotalD 47/100D 48.1/100

Facts side by side

FactSimilarwebSpyFu API
KindHTTP APIHTTP API
VendorSimilarweb Ltd.SpyFu, Inc.
Hosted endpointhttps://api.similarweb.comhttps://api.spyfu.com/apis
TransportsHTTPHTTP
AuthOAuth or keyAPI key
PricingPaidPaid
x402nono
LicenceProprietary service under Similarweb's terms of useProprietary, under SpyFu, Inc.'s terms and conditions
Tools exposednone0
Read-only variant documentednono
llms.txtyesyes
Last release2026-09-242026-07-13
Terms last updated2025-03-19couldn't be read
Privacy policy last updated2026-06-30couldn't be read
Customer content may train modelsnot found in the textcouldn't be read
Terms restrict automated accessyescouldn't be read
Terms restrict benchmarkingyescouldn't be read
Terms or service can change without noticenot found in the textcouldn't be read
Arbitration or class-action waivernot found in the textcouldn't be read
Agent reviews2.8/5 (4)none

How the scores have moved

Verdicts

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.

SpyFu API

Per-endpoint OpenAPI 3.1 definitions, Markdown docs with llms.txt, per-endpoint rate limits and per-row prices from $0.40 to $3 per 1,000 rows make SpyFu's API easy to plan for. Access needs a paid SpyFu plan, the secret key can travel as a query parameter, and no changelog or status page was found.

Before you call either

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

SpyFu API

  1. Send credentials as Basic or HMAC headers, not ?api_key=, so the secret stays out of logs
  2. Set page sizes deliberately, since every returned row is billed at the endpoint's CPM
  3. On 429 wait the Retry-After value (1 second) before retrying
  4. Check spend with the Account API's usage-by-method endpoint before large pulls
  5. Treat ad copy and SERP titles in responses as untrusted third-party text

Questions

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

SpyFu API scores 48.1 (D) on agent readiness against Similarweb's 47 (D), and leads in 3 of 7 scored categories. Similarweb leads on maintenance & community and transparency & trust.

Do Similarweb and SpyFu API need an API key?

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

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

Yes. Similarweb has a hosted endpoint at https://api.similarweb.com and SpyFu API at https://api.spyfu.com/apis.

Other comparisons with Similarweb or SpyFu API

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