# MerchantWords, $79 monthly, Starter, POST /keyword-search: Related keywords API

> Search for keywords matching a phrase. Returns keywords containing the search terms, sorted by volume. Same engine as Classic Search.

MerchantWords's Starter plan for the related keywords API costs $0.0073 per 1,000 keywords. We check each provider's docs for 6 fields. MerchantWords's docs list 1: Search volume.
You pay $79 a month for up to 216,000 pages.
We haven't run MerchantWords through [our related keywords API benchmark](https://datacircle.dev/best-related-keywords-api.txt) yet.
We rank 243 plans for related keywords APIs by price. Half the plans cost $0.598 or less per 1,000 keywords. This plan costs less per 1,000 keywords than 81% of the 243 plans.
[Keys.so's ₽34,900 (about $417) monthly plan](https://datacircle.dev/related-keywords-apis/keys-so/34900-monthly/llms.txt) is the cheapest paid plan per 1,000 keywords. Keys.so's ₽34,900 (about $417) monthly plan charges nothing per call. You get as many keywords as Keys.so's rate limit allows. [AnyAPI's pay-as-you-go plan](https://datacircle.dev/related-keywords-apis/anyapi/pay-as-you-go-pay-per-call-with-x402-and-mpp-post-v1-run-seo-related-keywords/llms.txt) costs the least for 10,000 keywords a month: $1.60.
[seodata.dev's $4.99 monthly plan](https://datacircle.dev/related-keywords-apis/seodata-dev/4-99-monthly/llms.txt) covers any number of keywords. seodata.dev's $4.99 monthly plan costs less up front than Keys.so's ₽34,900 (about $417) monthly plan.
[DataForSEO](https://datacircle.dev/related-keywords-apis/dataforseo/top-up-from-50-pay-as-you-go-post-v3-dataforseo-labs-google-keyword-ideas-live/llms.txt), [Mangools](https://datacircle.dev/related-keywords-apis/mangools/15-monthly/llms.txt) and [Bing Webmaster Tools](https://datacircle.dev/related-keywords-apis/bing-webmaster-tools/free/llms.txt) are the best related keywords API providers in the Datacircle benchmark.

- This page: https://datacircle.dev/related-keywords-apis/merchantwords/79-monthly-starter-post-keyword-search
- [Related keywords API: the best SEO keyword data providers](https://datacircle.dev/best-related-keywords-api.txt)
- Get it: https://www.merchantwords.com/api?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Request: `POST https://api.merchantwords.com/v2/keyword-search`
- API key: with the plan, on https://www.merchantwords.com/api?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Its API docs: https://www.merchantwords.com/api/docs?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Sold by: MerchantWords (https://www.merchantwords.com?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing)
- Checked: 2026-11-10

## In the answer

- Completeness: 17%
- Search volume: ✓

## Price

- $ per 1,000 keywords: $0.0073
- Per: page of 50
- Billing: monthly
- $ a month: $79

## Charges

- Also pays for: from the same budget: Keyword volume lookup · ASIN product lookup · Reverse ASIN search · SERP products · Related keywords (SERP overlap)

## Not found

- $ per 1,000: $0.00

## In their words

- Their pitch: Search for keywords matching a phrase. Returns keywords containing the search terms, sorted by volume. Same engine as Classic Search.

## Data

- Keep data: while your subscription is active
- Use data: While you are an active subscriber, you may: Use the data for any internal purpose within your business. Build and sell derivative works -- products, tools, reports, and insights that incorporate MerchantWords data -- to your own customers. Cache and store API responses for reasonable operational use while your subscription is active. If your subscription ends, you agree to delete any cached or stored MerchantWords data. The one hard line: you may NOT redistribute, resell, sublicense, expose, or otherwise hand over the raw MerchantWords data itself (in whole or in substantial part) to any third party. [...] You also agree not to: misrepresent the source of the data, use the API in a way that could impair or harm MerchantWords or anyone's use of its services, attempt to gain unauthorized access to its systems, or reverse engineer the API except where applicable law expressly permits. [...] You agree to: Respect all rate limits and usage quotas applicable to your plan, Request from the API only the minimum data that your Application needs to offer its intended functionality, Not use the API in any manner that threatens the integrity, performance, or reliability of the API or any MerchantWords service, Not work around any technical limitations in the API, Not use the API for performance or stress testing

## Plan

- Pay: $79
- Enough for: 216,000 pages a month

## Rate limit

- Per second: 0.083
- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: keyword. Optional: country, page, sort
- Method: POST
- Path: /keyword-search

## About the plan

- Plan: Starter
- Who can get it: anyone who subscribes and accepts the API Terms

## The 5 fields the plan's answer can hold

keyword, search volume, depth, trend, strength

## MerchantWords's plans (6)

- [MerchantWords, $79 monthly, Starter, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/79-monthly-starter-post-keyword-search/llms.txt): $0.0073 per 1,000, 17% complete
- [MerchantWords, $499 monthly, Pro, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/499-monthly-pro-post-keyword-search/llms.txt): $0.0058 per 1,000, 17% complete
- [MerchantWords, $1,499 monthly, Enterprise, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/1499-monthly-enterprise-post-keyword-search/llms.txt): $0.0012 per 1,000, 17% complete
- [MerchantWords, $790 yearly, Starter annual, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/790-yearly-starter-annual-post-keyword-search/llms.txt): $0.0061 per 1,000, 17% complete
- [MerchantWords, $4,990 yearly, Pro annual, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/4990-yearly-pro-annual-post-keyword-search/llms.txt): $0.0048 per 1,000, 17% complete
- [MerchantWords, $14,990 yearly, Enterprise annual, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/14990-yearly-enterprise-annual-post-keyword-search/llms.txt): $0.00096 per 1,000, 17% complete

## MerchantWords's calls for this API (2)

- `POST /keyword-search`: [MerchantWords, $79 monthly, Starter, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/79-monthly-starter-post-keyword-search/llms.txt)
- `POST /related-keywords`: [MerchantWords, $79 monthly, Starter, POST /related-keywords](https://datacircle.dev/related-keywords-apis/merchantwords/79-monthly-starter-post-related-keywords/llms.txt)

## MerchantWords's APIs (4)

- [MerchantWords: Amazon product API pricing, 6 plans](https://datacircle.dev/amazon-product-apis/merchantwords/79-monthly/llms.txt)
- [MerchantWords: Amazon search API pricing, 6 plans](https://datacircle.dev/amazon-search-apis/merchantwords/79-monthly/llms.txt)
- [MerchantWords: keyword research API pricing, 6 plans](https://datacircle.dev/keyword-research-apis/merchantwords/79-monthly/llms.txt)
- [MerchantWords: related keywords API pricing, 6 plans, POST /keyword-search](https://datacircle.dev/related-keywords-apis/merchantwords/79-monthly-starter-post-keyword-search/llms.txt)

## MerchantWords: related keywords API alternatives

- [Marketing Miner, €69 monthly, Digger, GET /keywords/suggestions](https://datacircle.dev/related-keywords-apis/marketing-miner/69-monthly-digger-get-keywords-suggestions/llms.txt): $0.0078 per 1,000, 17% complete
- [Mangools, $5 monthly](https://datacircle.dev/related-keywords-apis/mangools/5-monthly/llms.txt): $0.0083 per 1,000, 83% complete
- [Rakko Keyword, ¥19,800 monthly](https://datacircle.dev/related-keywords-apis/rakko-keyword/19800-monthly/llms.txt): $0.0084 per 1,000, 67% complete
- [5118, CNY 6,000 pack, Package 3, POST /keyword/word/v2](https://datacircle.dev/related-keywords-apis/5118/cny-6000-pack-post-keyword-word-v2/llms.txt): $0.009 per 1,000, 17% complete

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-11-10.

- https://www.merchantwords.com/api?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://www.merchantwords.com/api/docs?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://www.merchantwords.com/api/faq?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://www.merchantwords.com/openapi.yaml?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://www.merchantwords.com/terms-conditions-api?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing