What is the best SEO API?

What makes an SEO API the right one

An SEO API returns data about how pages and sites appear in search, in a form an agent or a script can process. The label covers several products. An audit inspects one page or a few pages and lists what is missing or malformed. Keyword data estimates how often people search for a term and how hard it is to rank for it. A search-results route returns what an engine shows for a query, and a rank check reports where one domain appears in that list. Domain footprints summarize the keywords a site ranks for and the traffic a provider estimates for it. Backlink data lists the sites that link to a domain or condenses the link graph into a score.

The best SEO API for one workflow can be the wrong one for another. A team shipping pages needs fast, repeatable audits of its own HTML. A content planner needs keyword volumes for a market and language. A rank tracker needs consistent search results for the same query every day. A link builder needs referring domains with dates. Comparing these products on price alone mixes units of work that answer different questions.

The second question is where the data comes from. Audits read the page you point them at, so their output is as fresh as the request. Keyword volumes, traffic estimates and link indexes come from a provider's own data or from a source it licenses, with its own refresh cycle and coverage. A provider that names its source, such as Google Ads data, Google Trends or the Common Crawl graph, tells you how to interpret the number.

This page compares 10 services that list a priced route of one of these products as of October 26, 2026. It leaves out 3 candidates that pass the listing checks but document no qualifying route.

Audits, keyword data, search results, domains and links

Endpoints are classified by what their descriptions say they return. Six products qualify a service for the table: an on-page or site audit, keyword volume and difficulty, Google Trends interest, search results and rank checks, a domain's organic footprint, and backlink or link-authority data. Single technical checks, citations in AI answers, keyword ideas without measured volume and drafts written from supplied inputs are classified separately. They appear beside a qualifying service, but they never qualify it on their own or supply its row price.

The split follows the kind of evidence. A Trends score is relative interest, an estimate from model training is not a measurement, and a plan written from the facts you supply contains no new search data. Keeping them in separate types means a cheap idea generator cannot stand in for a volume lookup.

Each price is the cheapest endpoint of that service for that kind of data: the same number wherever this page quotes it.

Scope claims come from the matched endpoint descriptions:

• A list of keywords in one call is accepted by CONNSKILL Growth Services and Citable.
• Several pages of a site are audited in one call by WebberSites x402 Data API and CONNSKILL Growth Services.
• Bing results or suggestions are named by CONNSKILL Growth Services and Citable.

Sources are named too:

• Google Ads data is named by CONNSKILL Growth Services.
• Google Trends is named by Google Trends SEO Keyword Data and CONNSKILL Growth Services.
• A licensed SERP feed is named by Citable.
• The Common Crawl graph is named by ForgeMesh SEO Authority.

A named source is the provider's statement; x402-list has not checked the figures against it.

Compare 10 SEO APIs

Each row is priced on the cheapest priced route of the six qualifying products, with the path printed under the price. Rows are ordered by distinct paying wallets over 30 days, a measure of use rather than data quality.

$/CALL is the price of the endpoint named under it: the cheapest on-page or site seo audit with findings, keyword volume, cost per click and difficulty, relative search interest from google trends, search results pages and rank checks, organic footprint of a domain: ranked keywords, visibility and competitors and backlink profiles and link-graph authority scores endpoint of the service or, for a service without one, its cheapest SEO endpoint. Never the cheapest tool of a gateway. Other kinds of data have their own price in the tables below. SEO ENDPOINTS counts the SEO endpoints out of all the endpoints the service lists. BUYERS 30D counts distinct wallets that paid the whole service on-chain in 30 days, not only its SEO endpoints. "Generalist" marks a gateway that sells more than three unrelated kinds of tools: it is never called the cheapest.

How to pick the best SEO API for your workflow

Start from the decision

Write down the decision the data supports: fix a page, choose a keyword, track a position, compare a competitor or plan outreach. Each decision maps to one product type, and the data-type table above shows which services sell it. A bundle that covers several types is convenient when you need every part; it is expensive when you need one.

Match the market

Keyword volumes and search results depend on country, language and engine. Check that the route accepts the locations you serve and records them in the response. A volume for the United States says little about Germany, and a Google result says little about Bing.

Check how audits read pages

Audits differ in what they fetch. A route can read raw HTML you supply, fetch the live page without running scripts, or load it in a browser. Pages assembled by JavaScript can fail a static check that a rendered audit passes. Test a few of your own templates with each candidate before trusting a score.

Understand estimates

Traffic, difficulty and authority figures are models built on a provider's index. They are useful for comparing pages or domains within one provider and misleading when mixed across providers. Keep the provider's name with each figure.

Plan for repeat calls

The median monitored uptime of the listed services is 99.9%. Monitoring checks the payment endpoint, not how long an audit or a large keyword batch takes, so time the calls you will repeat on a schedule.

Which endpoint fits which job

Pick the job by the output your next step consumes. Candidates come from the same endpoint classification as the table, and each quote keeps the path it came from, which can differ from the row price.

Audit a page before publishing

Decide whether you send a live URL or the HTML you are about to deploy, and whether the audit renders scripts. Keep the findings with the exact URL and time, and compare scores only within one provider's rules.

Candidates today, most buyers first: WebberSites x402 Data API ($0.001/call, generalist, 33 buyers) · CONNSKILL Growth Services ($0.03/call, 19 buyers) · HubVibe ($0.05/call, 11 buyers) · true402 ($0.02/call, generalist, 7 buyers) · ForgeMesh SEO Authority ($0.01/call, 6 buyers) · Citable ($0.01/call, 2 buyers) · x402.eleeth.com ($0.02/call, generalist, 1 buyer) · TradePilot Agent Commerce ($1.00/call, 1 buyer) · LaunchCheck Website Signals ($0.25/call)

Check crawler rules, metadata and structured data

Single checks are cheaper to repeat after each change. Confirm which bots a robots rule names, whether a sitemap lists the canonical URLs, and which structured-data types the check covers.

Candidates today, most buyers first: WebberSites x402 Data API ($0.001/call, generalist, 33 buyers) · true402 ($0.003/call, generalist, 7 buyers)

Size keyword demand

Record the location, language and month behind each volume. Advertising competition and organic difficulty are different measures, so keep them in separate columns.

Candidates today, most buyers first: CONNSKILL Growth Services ($0.03/call, 19 buyers) · Citable ($0.03/call, 2 buyers)

Track search results and positions

A position belongs to one engine, location, device and moment. Store the query parameters with every check, and repeat checks at a fixed schedule before reading a change as a trend.

Candidates today, most buyers first: CONNSKILL Growth Services ($0.03/call, 19 buyers) · Citable ($0.008/call, 2 buyers)

Benchmark a domain's organic footprint

Traffic and ranked-keyword counts are provider estimates from their own index. Compare domains within one provider rather than mixing figures from different sources.

Candidates today, most buyers first: CONNSKILL Growth Services ($0.05/call, 19 buyers) · Citable ($0.03/call, 2 buyers)

Review backlinks and link authority

A list of referring domains and an authority score answer different questions. Keep the index date with each result, since link indexes discover and drop links at their own pace.

Candidates today, most buyers first: CONNSKILL Growth Services ($0.15/call, 19 buyers) · ForgeMesh SEO Authority ($0.01/call, 6 buyers) · Citable ($0.1/call, 2 buyers)

Follow search interest over time

Trends values are relative to the strongest point in each request. Fetch related terms in the same request when you need to compare them, and never convert a score into a search count.

Candidates today, most buyers first: Google Trends SEO Keyword Data ($0.03/call, 42 buyers) · CONNSKILL Growth Services ($0.03/call, 19 buyers)

Check citations in AI answers

AI answers vary by prompt, model and day. Keep the prompts, engines and dates with each result, and read modeled AI demand as an indicator rather than a count of assistant queries.

Candidates today, most buyers first: CONNSKILL Growth Services ($0.05/call, 19 buyers) · Citable ($0.18/call, 2 buyers)

What the main providers describe

These notes repeat what each provider documents for its SEO routes, as read on October 22, 2026. Sources, limits and billing rules are the providers' statements; prices come from the matching endpoint type, never from figures written in a description.

Citable

Citable lists GET routes across audits, keyword data, search results, domain footprints, backlinks and AI citations. Its on-page audit of one URL scores title, meta, headings, links, images, structured data and word count at $0.01. Keyword data starts at $0.03; the metrics route takes up to 20 keywords per call and returns volume, cost per click, competition, difficulty and intent. GET /v1/serp returns the raw Google results page with organic results, People Also Ask and related searches, and search-result routes start at $0.008; the provider says rank checks come from a licensed SERP feed. Backlink totals with top referring domains cost $0.1. The provider states that a 4xx or 5xx response cancels the payment instead of settling it, and its listing names Solana as the payment network.

17 SEO endpoints of 17 · $0.008/call (GET /v1/serp) · SOL · uptime 30d 100% · 199 ms · 2 buyers in 30 days

CONNSKILL Growth Services

CONNSKILL Growth Services sells keyword, search-result, domain and backlink data as separate POST routes. Its keyword metrics come from Google Ads data for up to 1,000 terms, and the provider notes that advertising competition is not organic SEO difficulty; a separate route scores ranking difficulty from 0 to 100. Keyword data starts at $0.03, search results at $0.03, domain visibility at $0.05 and backlink data, with the top 25 referring domains, at $0.15. POST /v1/site-audit bundles a traffic estimate, ranked keywords, competitors, a backlink profile and an on-page crawl of up to 20 pages. The provider says partial results stay explicit and that its ranked-keyword snapshot does not monitor positions automatically.

19 SEO endpoints of 41 · $0.03/call (POST /v1/page-audit) · Base · uptime 30d 99.1% · 155 ms · 19 buyers in 30 days

WebberSites x402 Data API

WebberSites x402 Data API splits page checks into single-purpose GET routes, with audits from $0.001. The head check reviews title and description length, robots meta, canonical status, hreflang and H1 count. The full audit runs seven analyses on one URL, from metadata and alt text to schema.org and robots rules, with a 0-100 score and itemized deductions, and the site audit repeats them across up to eight pages found through internal links. Robots, sitemap, structured-data and social-card checks start at $0.001. The navigation extractor states that it reads server-rendered HTML and flags menus that appear to be built in the browser.

12 SEO endpoints of 37 · $0.001/call (GET /api/seo/head-check) · Base · uptime 30d 100% · 186 ms · 33 buyers in 30 days

Google Trends SEO Keyword Data

Google Trends SEO Keyword Data wraps Google Trends in four GET routes from $0.03. The interest series gives monthly popularity since 2004, worldwide or for one country. Regional interest ranks every region of a country from 0 to 100 against the strongest, and related queries and topics list top terms on the same scale plus rising terms with percentage growth. Each value is relative to the strongest point in the request, so a Trends score of 100 is not a search volume, and results for different term sets do not share a common scale.

4 SEO endpoints of 4 · $0.03/call (GET /interest-by-region) · ARB/Base/POL/SOL · uptime 30d 99.9% · 249 ms · 42 buyers in 30 days

HubVibe

HubVibe lists audit routes from $0.05. POST /audit/seo checks a live URL or raw HTML for the title tag, meta description, H1 structure, canonical link, social tags, JSON-LD and the html lang attribute, with a severity for each finding. POST /audit/bundle adds accessibility, security headers and page weight from a single browser load, and the provider says nothing is billed if any part cannot run. Its page-weight check counts bytes, requests and DOM nodes, which the provider distinguishes from Core Web Vitals.

2 SEO endpoints of 15 · $0.05/call (POST /audit/seo) · Base/SOL · uptime 30d 99.9% · 200 ms · 11 buyers in 30 days

ForgeMesh SEO Authority

ForgeMesh SEO Authority runs deterministic on-page checks on supplied HTML at $0.01 and states that the score does not claim page authority. Its authority routes start at $0.01 and compute open-web domain authority from Common Crawl graph metrics, for one domain or a comparison of 2 to 20. That is a graph score rather than a list of linking pages. The service description also names content briefs, competitor gaps and internal-link intelligence, which do not appear in the captured endpoint list.

5 SEO endpoints of 5 · $0.01/call (POST /v1/url-seo-score) · Base · uptime 30d 99.9% · 216 ms · 6 buyers in 30 days

What SEO data costs at volume

The median selected call costs $0.025, so 100,000 calls total $2,500.00 at that rate. The table repeats the calculation for the median, the cheapest specialized service and the providers described above.

Each service at the price of its main SEO endpoint, the one named in the table above.

The unit behind a call varies. One audit route checks a single page, another crawls several; one keyword call returns metrics for a single seed, another for a long list of terms. Convert your workload into calls before comparing: tracking 200 keywords in five markets every day is 1,000 rank checks a day, while a monthly volume refresh for the same terms can fit in a handful of batch calls.

Bundles change the arithmetic only when their parts match yours. A bundle saves money if its price is below the sum of the separate routes you would otherwise call for the same pages and data. The parts do not always line up: a bundled audit may crawl several pages where the separate audit checks one URL, or add checks you would not otherwise buy. Add up the separate quotes for the parts you would actually use before choosing, and read a provider's statement that its bundle is cheaper as that provider's claim. Keep the route with each charge so a bill can be matched to the data you kept.

Inspect a search-results request and its payment terms

For search results, Citable documents GET /v1/serp. Read its current request schema for the query, location and language before paying, and check that the response separates organic results from People Also Ask and related searches. The catalog reference quote for this method and path is $0.008; it is not a verified quote for a different method or request body.

The listed method and description establish the advertised contract. This explanation does not reproduce an HTTP 402 challenge or certify a paid response. Request the challenge for the exact call you intend to make and compare resource, method, network, asset and amount before authorizing payment. A challenge for a keyword or backlink route on the same host does not authorize a search-results request.

How this comparison is built

The comparison starts from services that are online and payment-ready, with a known price, a description of at least 80 characters and measured 30-day uptime of at least 90%. Endpoint selection then reads each service's documented routes. A service enters the table only with a priced audit, keyword-data, Trends, search-result, domain or backlink route. Single technical checks, AI-citation products, keyword ideas without volume, estimates from model training and plans written from supplied inputs are shown beside a qualifying service without qualifying it. Repository discoverability scores, accessibility-only and security-header audits, WHOIS and technology-stack lookups stay out of the classification.

Descriptions and endpoint lists were read from the public listing on October 22, 2026. Sources, limits and billing rules quoted here are provider claims; x402-list has not tested the accuracy of audits, volumes, positions or link counts. Buyer counts are distinct paying wallets over 30 days, and monitoring measures availability and response time of the payment endpoint.

Prices are the reference amounts listed for each endpoint. A route with tiers, batch sizes or quotes before purchase can cost a different amount for your request, so treat the reference price as a starting point.

Questions

How to pay

Each service answers an unpaid call with HTTP 402 and its price; your agent signs a USDC payment on the listed network and retries. No API key, no account, no subscription. See what x402 is.