SEO APIs you can pay per call

What an SEO API does, and who calls it

An SEO API exposes a specific part of search optimization as structured output. A caller might submit a URL for an HTML checklist, a keyword for demand estimates, a domain for backlink information or a prompt for AI citation research. The word SEO alone does not identify the source, the observation or the action that a response supports.

For an agent, the useful unit is a bounded research step: check a canonical before drafting a recommendation, retrieve a dated keyword series before proposing a content calendar, or attach cited pages to a visibility report. A web search tool may help that process, but generic web search is not automatically a keyword database. A generated outline similarly does not establish that its proposed phrases have measured traffic.

This page groups the documented paid endpoints by their actual product. It includes 12 services as of October 26, 2026 and leaves out 1 candidate meeting the listing checks but lacking a matching priced task endpoint. Provider descriptions explain intended outputs; our monitoring figures explain observed availability and payment activity. Neither substitutes for checking the returned SEO data against a small, known example.

What the 12 SEO services actually return

The classification follows documented endpoint products. It counts services per type, so a service offering more than one product can appear in more than one row. Each quote comes from the cheapest priced endpoint of that type, with its source route attached.

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

Use this table to narrow the product before comparing hosts. A matching type identifies an advertised output, not verified accuracy or complete coverage of your input. The request schema, source period and returned missing-value states still need to fit the job. Read the service-specific notes below for limits that a broad product label cannot express.

The endpoint descriptions name Common Crawl for ForgeMesh SEO Authority and model-training estimates for GigSoul x402 API. Those are different evidence bases; retain the source label when exporting the output.

The 12 SEO APIs and their matching endpoint prices

One row per service, ordered by measured buyers. The price names the selected task route rather than an unrelated utility on the same host. Primary types determine the preferred quote; a service without a primary type uses its cheapest matching task endpoint.

$/CALL is the price of the endpoint named under it: the cheapest on-page checks, metadata and crawl rules 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.

The buyer figure covers the host's measured payments, so it does not establish demand for this particular endpoint. A gateway can sell unrelated tools and a reseller can share an upstream source with another listing. Use these signals to investigate operational fit rather than inferring independent data collection or product quality from wallet counts.

How to choose an SEO API

Decide what is being measured

A page audit can identify an absent title or canonical in the inspected document. It cannot, from that fact alone, establish search-engine indexing, field performance or a ranking effect. Ask whether the request reads supplied HTML, fetches one URL, renders JavaScript or crawls linked pages. Set that scope before comparing a score.

Keep source and geography attached

Search-volume estimates depend on the dataset and target market. A relative Trends value has a different meaning from estimated searches per month. A graph authority score is a provider's calculation over its source graph. When combining responses, preserve engine, country, language, device, period and source instead of exporting an unlabeled number.

Treat AI visibility as an observation

An answer engine may cite different pages when the prompt, engine or time changes. Request the observed prompt and source URL when you need an auditable citation record. Keep an aggregate share-of-voice calculation separate from a single generated answer, and avoid turning a successful sample into a promise of persistent placement.

Match the evidence to the recommendation

For a content plan, separate supplied facts, retrieved evidence and generated suggestions. This helps an editor see whether a proposed topic addresses a real gap or merely repeats an input phrase. Before scheduling work, inspect duplication, target intent and the business's ability to substantiate the proposed claims.

Which endpoint fits which job

Start with the job, then compare the candidates whose classified endpoints match it. The price in a job table is tied to those types, which can differ from the service's selected price in the main table. Do not assume that one host's entry quote covers another product it sells.

Check a page before release

Choose the input you actually have: a public URL, raw HTML or a sitemap. For a JavaScript application, ask whether the tool renders the page. Record individual failures and the inspected HTML revision; a score without the underlying checks is difficult to use in a release review.

Candidates today, most buyers first: WebberSites x402 Data API ($0.001/call, generalist, 33 buyers) · HubVibe ($0.05/call, 11 buyers) · true402 ($0.003/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)

Research demand and seasonality

Separate absolute estimates from relative interest indices. Require the country, language, search engine, date range and refresh date that your planning decision needs. Compare a seed keyword and a known seasonal query before loading a large research job, then keep the source attached when exporting results.

Candidates today, most buyers first: Google Trends SEO Keyword Data ($0.03/call, 42 buyers) · CONNSKILL Growth Services ($0.03/call, 19 buyers) · Citable ($0.03/call, 2 buyers)

Monitor results, links and citations

Define the observation before comparing providers: organic search position, a link-graph score and an AI answer citation use different denominators. Save the prompt or search query and observation time. Repeating a request with different location or engine settings can change the answer without showing that a website changed.

Candidates today, most buyers first: ForgeMesh SEO Authority ($0.01/call, 6 buyers) · Citable ($0.008/call, 2 buyers)

Turn research inputs into a content plan

Use supplied-input planning when you already have reviewed keywords, business facts and page URLs. Require the output to distinguish evidence from proposed actions. A cluster or landing-page draft should stay a draft until an editor checks intent, duplication and factual business claims against the original material.

Candidates today, most buyers first: ForgeMesh SEO Authority ($0.005/call, 6 buyers) · Citable ($0.005/call, 2 buyers) · TradePilot Agent Commerce ($0.25/call, 1 buyer) · GigSoul x402 API ($0.04/call)

Improve a repository listing

Repository discoverability concerns the README, description, topics and linked homepage. It is useful for a developer tool whose first impression is a GitHub page. Keep this checklist separate from a rendered website audit, and verify which repository revision the tool inspected before accepting the proposed changes.

Candidates today, most buyers first: Agent Web Reader (x402) ($0.005/call, 13 buyers)

Service details and limits to check

The notes below are read from the provider's description and endpoint list captured on October 21, 2026. They attribute advertised capabilities and source information; x402-list has not independently tested the accuracy of the delivered data or generated output. Price, uptime and buyer tokens come from the current page model.

Citable

Citable describes several separate research products. The description of /v1/onpage-audit lists checks for a page's metadata, headings, links, images and structured data at $0.01. Its keyword-data endpoints start at $0.03; the descriptions distinguish keyword metrics, keyword discovery and a domain's organic footprint. Search results and rank checks start at $0.008, while backlinks cost $0.1. For AI discovery, it advertises engine visibility and observed citations, including cited prompts and top cited pages, from $0.18. Treat the provider's claim about licensed SERP and official engine access as source information, rather than an accuracy test by x402-list. A keyword suggestion, a keyword-volume estimate and an observed citation need different storage fields and dates.

17 SEO endpoints of 17 · $0.01/call (GET /v1/onpage-audit) · SOL · uptime 30d 100% · 199 ms · 2 buyers in 30 days

ForgeMesh SEO Authority

ForgeMesh SEO Authority says its domain authority comes from the Common Crawl web graph. The authority endpoints start at $0.01; the description of /v1/authority-compare says it compares supplied domains. This is a graph-derived measure, so it should retain its source label when exported to a report. The supplied-HTML scorer /v1/url-seo-score costs $0.01 and is described as checking whether the submitted page meets deterministic SEO criteria. Query correction and expansion start at $0.005. Those tools describe transformations of the query, without promising measured keyword demand. Keep their suggestions separate from a search-volume column rather than treating a plausible phrase as a measured opportunity.

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

HubVibe

HubVibe describes /audit/seo as an on-page check for a public URL or raw HTML: title, meta description, primary heading, canonical, Open Graph, JSON-LD and language. Its SEO-type price starts at $0.05. The bundle description also lists accessibility, security and page-weight checks; the provider says a failed component prevents billing for the bundle. Page weight is not a Core Web Vitals measurement. For a release workflow, save the input URL or HTML revision with the returned findings, then compare the next run against that same scope. This makes a missing canonical actionable without presenting the audit score as a forecast of future rankings.

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

TradePilot Agent Commerce

TradePilot Agent Commerce lists a technical URL audit at $1.00 and planning tools from $0.25. The endpoint descriptions distinguish the planning inputs: keyword_cluster groups supplied keywords, keyword_page_map maps supplied keywords to pages, and content_gap works from supplied site and competitor information. The descriptions explicitly limit these planning tools to the input material; a generated plan does not establish live competitor research or measured search volume. The separate SEO page product is described as generating a landing page from business, service and location inputs. Review factual business claims and the intended page before publishing generated copy. The listing describes a drafting workflow, not a guarantee of indexing or traffic.

8 SEO endpoints of 75 · $1.00/call (POST /api/agent-commerce/v1/seo-audit) · Base · uptime 30d 99.6% · 334 ms · 1 buyer in 30 days

Google Trends SEO Keyword Data

Google Trends SEO Keyword Data describes a dated interest series, regional interest, related queries and related topics. Its matching calls start at $0.03. The regional and related-query descriptions specify relative indices, including values on a scale up to 100; those values are not a count of monthly searches. The trend endpoint describes history back to 2004 with country targeting. Compare like-for-like geography and time windows before drawing a seasonal conclusion. A rise in a related query can suggest a topic to investigate, while a keyword-volume dataset answers a separate budget question. Preserve the query, region and selected interval beside the response so that another analyst can reproduce the comparison.

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

GigSoul x402 API

GigSoul describes /analyze-seo-keywords as providing keyword estimates based on model training data rather than live search data. The planning call costs $0.04. That distinction matters when a generated list enters a spreadsheet: label it as an estimate or an idea, keep the provider's stated basis attached, and avoid silently merging it into a measured volume feed. It can supply starting phrases for a content discussion. Before using those phrases to allocate paid editorial effort, validate present demand with a dated source and review the intended search intent. The task table classifies this endpoint as planning so its quote does not become the price of observed search metrics.

1 SEO endpoint of 23 · $0.04/call (GET /analyze-seo-keywords) · Base · uptime 30d 100% · 125 ms · 0 buyers in 30 days

What the calls cost at different volumes

The median selected endpoint costs $0.025 per call. At that same request shape, 100,000 calls would cost $2,500.00. This multiplication is a comparison aid, not a provider invoice or a promise that an arbitrary request will use the reference quote.

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

Budget for useful results as well as submissions. A retry, an additional research step or a separate product can add another charge; no-match and partial-failure handling depend on the particular endpoint. For a variable body, model or input size, inspect the returned payment requirement for that exact request. Keep the quoted route and paid unit in the job record rather than projecting from the cheapest unrelated tool on a gateway.

How an agent reaches the HTTP 402 payment step

An unpaid request lets the caller inspect a payment requirement. The example below pairs the documented route with a real HTTP 402 payload previously captured by x402-list's monitor. Its capture date belongs to that evidence; it is not a claim that a paid result was tested today. The documented route has a reference quote of $0.01; inspect the challenge for the exact request terms.

curl -i 'https://citable.run/v1/onpage-audit?url=https%3A%2F%2Fexample.com'

HTTP/1.1 402 Payment Required

{
  "x402Version": 2,
  "resource": {
    "url": "https://citable.run/v1/onpage-audit"
  },
  "accepts": [
    {
      "asset": "EPjFWdd5AufqSSqeM2qN1xzybapC8G4wEGGkZwyTDt1v",
      "extra": {
        "feePayer": "CjNFTjvBhbJJd2B5ePPMHRLx1ELZpa8dwQgGL727eKww"
      },
      "payTo": "6nWrWRTqrqpqbu5MsMW8mPDpZjKLwPb9Wf8BdMwNMWzK",
      "amount": "10000",
      "scheme": "exact",
      "network": "solana:5eykt4UsFv8P8NJdTREpY1vzqKqZKvdp",
      "maxTimeoutSeconds": 300
    }
  ]
}

402 of Citable for GET /v1/onpage-audit, as stored by the monitor (terms unchanged since 2026-08-31, last check 2026-10-26 17:43 UTC), with every accepted payment exactly as stored and without error, extensions, resource.mimeType and resource.description, which are not payment terms: the full body is also on the service page, under Payment evidence. Amounts are in the asset's smallest unit: USDC has 6 decimals, so 10000 is $0.01.

Inspect the request schema before adapting the example. A documented POST endpoint needs the corresponding JSON inputs; a GET endpoint needs valid query values. Keep the payment requirement tied to the intended resource, network, asset and request. The captured challenge shows what payment access looks like. It does not prove that a paid call will return accurate output, complete a background job or satisfy the application's success criteria.

What this comparison measures

The listing requires an online, payment-ready service, a usable description, an advertised price and at least 90% measured uptime over 30 days. Task selection then reads its endpoint list and keeps the matching routes. Those listing checks establish a discovery threshold, not a certification of output accuracy.

Uptime is based on monitoring checks; average latency measures those checks. Buyer counts are distinct paying wallets observed for the service in the measurement window, with the limits described on the service page. A successful unpaid HTTP 402 response confirms a payment challenge rather than successful delivery after settlement.

Treat the provider's output contract and our monitoring as complementary evidence. Test a representative input, inspect source dates and missing states, and define a successful result before putting a recurring workflow on the endpoint. For comparison details, open the linked service page and the site's measurement methodology. Recheck the exact payment requirement when the input or advertised product changes.

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.