2026-10-26, SERP API · Rank Tracking · GEO · Fundamentals

Best SEO APIs for 2027: SERP, keywords, backlinks, AI data

“SEO API” covers six different data types: live search results, keyword search volume, backlinks, site audits, rank tracking and AI visibility. No single row of a pricing page buys all six at the same unit, so the useful comparison is by data type: which vendor sells which one, through which access model, at what entry price. This guide is for teams setting 2027 budgets; every fact is as of October 2026.

Facts about each vendor come from its own pages, linked and checked on 2026-10-26; “not found” means not on those pages on that date, and “price on request” means the vendor publishes none. Moz also sells an API; its pages could not be loaded on 2026-10-26, so it is not compared here. For SERP vendors alone, see the best SERP APIs and the cheapest SERP API.

Comparison by data type

Three access models sit in that table:

• Suite plans with API units (Ahrefs, Semrush, SE Ranking, Similarweb): one subscription, many data types, units or credits deducted per row or request.
• Per-call data vendors (DataForSEO, SerpApi, AnswerLine, Majestic’s API plan): you pay for each request or each results page, and build the product yourself.
• First-party data (Search Console): exact numbers for sites you own, free, and nothing about anyone else.

Which data type needs which source

1. SERP data: what the results page shows now for a query, location and device. Every vendor with a SERP column collects it live; quality differs in parsed features (AI Overview, local pack, People Also Ask).
2. Keyword volume: how often a query is searched. It comes from Google Ads data or a vendor’s clickstream model, never from the results page. SERP data vs search volume data explains the split.
3. Backlinks: a crawler’s link index. Index size and freshness are the vendor’s own crawl, so numbers differ between Ahrefs, Majestic, Semrush and DataForSEO.
4. Site audit: a crawl of your own site for technical issues.
5. Rank tracking: SERP data on a schedule, stored as positions. Suites sell it as a project; per-call vendors leave the schedule to you.
6. AI visibility: what ChatGPT, Gemini, Google AI Mode and other assistants say, and which pages they cite.

The options

Ahrefs API

Ahrefs’ API v3 is available on Lite and higher plans. Its SEO API page and pricing list Lite at $129 a month with 200,000 API units and 100 rows per request, Standard at $249 with 800,000 units and 250 rows, Advanced at $449 with 2 million units and 500 rows, and Enterprise at $1,499 a month on an annual commitment with unlimited rows. Each request costs at least 50 units; Rank Tracker, management and public endpoints use no units.

Data covers Site Explorer (backlinks and organic data), Keywords Explorer, SERP Overview (top 100), Rank Tracker, Site Audit, GSC Insights and Brand Radar, which tracks AI Overviews, AI Mode, ChatGPT, Gemini, Copilot and Perplexity. The SEO API page lists 217 locations. Brand Radar AI is sold from $199 a month. Free test queries work against ahrefs.com, yep.com and firehose.com.

Units are spent per row, so a 500-row backlink export costs more than a 10-row lookup. Rows per request rise with the plan, which matters for bulk exports.

Fits teams that want every data type, including backlinks and AI visibility, from one index and one key.

Semrush API

Semrush’s Standard API, covering Analytics and Projects, is an add-on to the Business plan, and a Business account starts with 0 API units (API access). Units come in packages of 2M, 5M, 10M or 20M, expire with the plan, and their price is not published (knowledge base). Example costs: Domain Organic Search Keywords is 10 units per line for live data and 50 for historical; Backlinks is 40 units per line. Requests are limited to 10 per second per IP and 10 simultaneous per user.

Analytics covers domain, keyword and backlink reports; Projects covers Position Tracking and Site Audit campaigns. The Trends API (traffic data) is separate, with a default of 10,000 requests a month. Semrush’s MCP documentation says Semrush One Starter, Pro+, SEO Classic Pro and Guru include 50,000 API units. The prices page lists SEO at $139 a month, Starter $199, Pro+ $299 and Advanced on request, with a 7-day trial. Starter includes 50 AI prompts tracked daily in the app; no API for that AI visibility data was found on its pages.

Per-line pricing makes historical keyword data five times the cost of live data. The unit price has to be requested before you can model a budget.

Fits teams already on Semrush whose reports depend on its keyword and backlink databases.

DataForSEO

DataForSEO sells each data type as a separate API on one pay-as-you-go balance: $50 minimum top-up, $1 trial credit (pricing).

Location, language and device do not change the SERP price. Since 2026-07-01 the Backlinks API has no $100 monthly commitment, and its prices rose 20%.

The cheapest SERP price is a queue; live results cost more than three times as much. Each API has its own task model and response vocabulary to learn.

Fits teams building their own SEO product that want every data type priced per call, with no subscription.

SE Ranking API

SE Ranking’s API pricing page (prices in euros) lists a 14-day trial with 100K credits, a Wallet at €45 for 250K credits that never expire, a standalone plan at €155 a month billed annually with 1M credits a year for the Data API, and an add-on at €39 a month billed annually with 250K credits a year, which needs a Core, Growth or Enterprise plan. The Data API covers keywords, backlinks, domains, SERP data, site audits and AI visibility in 188+ regions; the Project API runs rank tracking inside the app.

The per-request credit cost varies by endpoint, so convert credits to calls for your own request mix before comparing.

Fits agencies already on SE Ranking and teams that want a suite’s data types at a lower entry price than Ahrefs.

Similarweb API

Similarweb’s API is sold with Business and Enterprise plans or as a standalone package, on data credits, price on request. It covers traffic and engagement, keywords, apps and technographics, with history up to 7 years. No SERP, backlink or AI visibility data was listed.

Fits market and traffic research, next to a separate SERP or backlink source.

Majestic API

Majestic’s API plan is €379.99 a month, or €316.66 a month billed annually, excluding VAT, with 100M analysis units and 20M retrieval units. The LITE (€46.99) and PRO (€94.99) plans have no API. It is backlinks only, from a Fresh index (120 days) and a Historic index (since 2006).

Fits link-data products that want a second link index or history back to 2006.

SerpApi

SerpApi’s plans run from a free 250 searches a month to Starter at $25 for 1,000, Developer $75 for 5,000, Production $150 for 15,000, Searcher $725 for 100,000 and Cloud 1M at $3,750. Only successful searches count, and each plan has a guaranteed hourly throughput. Its catalog covers Google Search with AI Overview, a Google AI Mode engine, Maps, Local, Trends and other engines; no search volume or backlink API is listed (engine directory).

Fits products that need many search engines and Google verticals as SERP data.

Google Search Console API

The Search Console API is free. Search Analytics returns clicks, impressions, CTR and average position, grouped by query, page, country, device, search appearance or date, up to 25,000 rows per request (query reference) and at most 50K rows per day per search type (all your data). Quotas are 1,200 queries per minute per site (limits). Data arrives after 2 to 3 days, and Google says Search Console keeps the last 16 months (Google help).

It covers only sites you have verified, and position is an average across all impressions, not a check from one location.

Fits every site owner, next to any paid source.

AnswerLine

AnswerLine returns what Google Search and AI assistants show people, as JSON. The Google Search response has organicResults, ads, peopleAlsoAsk, relatedSearches, knowledgeGraph, localResults, shoppingCards and, with include.aioverview, the AI Overview with its sources. Requests take country, location (a Google canonical name such as Austin,Texas,United States) or uule, hl and device, and up to 10 pages. The same account returns ChatGPT, Gemini, Perplexity, Copilot, Grok and Google AI Mode answers with their cited sources, and Google News results.

curl -X POST https://api.answerline.dev/v1/monitor/google \
  -H "Authorization: Bearer $API_KEY" \
  -H "Content-Type: application/json" \
  -d '{ "query": "crm for small business", "country": "US", "include": { "aioverview": {} } }'

A Google Search request is $0.00103 for one page on every tier; each extra page adds $0.00071, and the AI Overview adds $0.00071 when Google shows one. A ChatGPT answer is $0.0006 at the Starter tier ($0.42–$0.60 per 1,000 across tiers). A new account gets 100 free requests, failed requests are not charged, and every tier is on /pricing. Batches take up to 500 tasks with idempotency keys and signed webhooks.

It has no search volume, backlink or site audit data, and rank tracking is a pipeline you build on Google Search requests. The keyword research use case covers what the results page tells you without volume.

Fits products that report Google rankings and AI answers side by side and pair them with a volume or link source.

How to choose

1. List the data types your report or product needs. Backlinks narrow the list to Ahrefs, Semrush, DataForSEO, SE Ranking and Majestic; AI visibility to Ahrefs, DataForSEO, SE Ranking and AnswerLine.
2. Decide between a suite and per-call vendors. A suite plan fits when people use the app and the API feeds a few reports; per-call pricing fits when the API feeds your own product.
3. Convert units to calls. Ahrefs and Semrush charge per row, SE Ranking per credit, DataForSEO per task and row, SerpApi and AnswerLine per request. Price the requests you will send, at the depth you need.
4. Check latency. Queued modes are cheapest; interactive tools need live calls.
5. Check whose data it is. Search Console is exact for your own site; every other source is collected or modelled.
6. Check what a failed call costs. SerpApi counts only successful searches; AnswerLine does not charge failed requests.

Cost example

A 2027 plan for one product: 2,000 keywords tracked daily in one market (60,000 results pages a month), monthly search volume for the same 2,000 keywords, and 100 prompts asked to ChatGPT daily (3,000 answers a month). List prices checked 2026-10-26, before taxes and discounts.

The suite line cannot be converted to a per-call figure without knowing your row counts. DataForSEO’s $50 minimum top-up applies once, and its balance does not expire. AnswerLine has no volume data, so pair it with a volume source.

Pitfalls

• Mixing positions from different sources. A Search Console average position and a SERP position from one location measure different things.
• Comparing backlink counts across vendors. Each has its own crawler and index.
• Ignoring row-based units. A suite’s unit allowance runs out on large exports sooner than on lookups.
• Assuming volume comes with SERP data. It does not; SERP APIs return the page.
• Treating one AI answer as a ranking. Answers vary run to run; see AI answer volatility.

Field-level detail is on the Google Search engine page, and the quickstart covers a first request.

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