# SignalSumo, $99 monthly: Related keywords API

> Returns a full metric set for a seed keyword — search volume, CPC, competition, difficulty, search intent, a 12-month volume trend, SERP features and more — plus a ranked list of related keywords carrying the same fields.

SignalSumo's "Pro — monthly" plan for the related keywords API costs $49.50 per 1,000 keywords. We check each provider's docs for 6 fields. SignalSumo's docs list all 6: Search volume, Monthly trend, Cost per click, Competition, Keyword difficulty, Search intent.
We haven't run SignalSumo through [our related keywords API benchmark](https://datacircle.dev/best-related-keywords-api.txt) yet.
We rank 253 plans for related keywords APIs by price. Half the plans cost $0.735 or less per 1,000 keywords. 2 of the 253 plans cost more per 1,000 keywords than this plan.
[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, with no charge 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, and 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/signalsumo/99-monthly
- [Related keywords API: the best SEO keyword data providers](https://datacircle.dev/best-related-keywords-api.txt)
- Get it: https://signalsumo.com/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Request: `POST https://signalsumo.com/api/v1/keyword-research`
- API key: with the plan, on https://signalsumo.com/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Its API docs: https://signalsumo.com/api-docs?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Sold by: SignalSumo (https://signalsumo.com?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing)
- Checked: 2026-11-12

## In the answer

- Completeness: 100%
- Search volume: ✓
- Monthly trend: ✓
- Cost per click: ✓
- Competition: ✓
- Keyword difficulty: ✓
- Search intent: ✓

## Price

- $ per 1,000 keywords: $49.50
- Per: page of 100
- Billing: monthly
- $ a month: $99

## Charges

- Also pays for: from the same budget: GET Usage · GET Backlinks · POST Site Audit · GET Jobs · GET Tracked Keywords · GET Rank History · GET GSC Properties · GET GSC Queries · GET AI Projects · GET Share of Voice · GET Locations

## Overage

- Units cap: hard

## Not found

- $ per 1,000 calls that find nothing: $4,950.00

## In their words

- Their pitch: Returns a full metric set for a seed keyword — search volume, CPC, competition, difficulty, search intent, a 12-month volume trend, SERP features and more — plus a ranked list of related keywords carrying the same fields.

## Data

- Keep data: no limit
- Use data: The reports, analysis outputs, and data exports generated by the Platform for your account are yours to use for your own business purposes. You may not resell or redistribute Platform outputs as a standalone data product without our express written consent. [...] You must not: [...] Share account credentials with third parties or resell access to the Platform without authorisation. [...] Use any output from the Platform to engage in spam, phishing, or other deceptive practices.

## Plan

- Pay: $99
- You get: 20 requests a month
- Enough for: 20 pages a month
- Expires: 1st of each month

## Rate limit

- Per second: 0.33 (20 a minute)
- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: keyword, Content-Type header "application/json". Optional: location_code, language_code, limit
- Method: POST
- Path: /keyword-research

## About the plan

- Plan: Pro — monthly
- Who can get it: anyone at least 18 years old and able to form a binding contract

## The 22 fields the plan's answer can hold

source keyword, location code, language code, total results, keyword, search volume, cost per click, competition, competition level, keyword difficulty, intents, search volume trend, search volume growth, SERP features, low top of page bid, high top of page bid, average backlinks, average referring domains, competing domain rank, search results count, related sub-keywords, match bucket

## SignalSumo's plans (4)

- [SignalSumo, $99 monthly](https://datacircle.dev/related-keywords-apis/signalsumo/99-monthly/llms.txt): $49.50 per 1,000, 100% complete
- [SignalSumo, $249 monthly](https://datacircle.dev/related-keywords-apis/signalsumo/249-monthly/llms.txt): $24.90 per 1,000, 100% complete
- [SignalSumo, $990 yearly](https://datacircle.dev/related-keywords-apis/signalsumo/990-yearly/llms.txt): $41.25 per 1,000, 100% complete
- [SignalSumo, $2,499 yearly](https://datacircle.dev/related-keywords-apis/signalsumo/2499-yearly/llms.txt): $20.825 per 1,000, 100% complete

## SignalSumo's calls for this API (1)

- `POST /keyword-research`: [SignalSumo, $99 monthly](https://datacircle.dev/related-keywords-apis/signalsumo/99-monthly/llms.txt)

## SignalSumo's APIs (4)

- [SignalSumo Backlink API pricing, 4 plans](https://datacircle.dev/backlink-apis/signalsumo/99-monthly/llms.txt)
- [SignalSumo Domain authority API pricing, 4 plans](https://datacircle.dev/domain-authority-apis/signalsumo/99-monthly/llms.txt)
- [SignalSumo Keyword research API pricing, 4 plans](https://datacircle.dev/keyword-research-apis/signalsumo/99-monthly/llms.txt)
- [SignalSumo Related keywords API pricing, 4 plans](https://datacircle.dev/related-keywords-apis/signalsumo/99-monthly/llms.txt)

## SignalSumo: related keywords API alternatives

[SignalSumo alternatives: other related keywords API providers by price](https://datacircle.dev/signalsumo-alternatives.txt)

We list other providers' plans closest to this plan in price per 1,000 keywords. We also show the SEOZoom plan. Its price is farther from this plan's price.

- [EverBee, top-up](https://datacircle.dev/related-keywords-apis/everbee/top-up/llms.txt): $7.50 per 1,000, 33% complete
- [Morningscore, $69 monthly](https://datacircle.dev/related-keywords-apis/morningscore/69-monthly/llms.txt): $13.80 per 1,000, 50% complete
- [Local SEO Data, top-up from $5, Pay-As-You-Go, POST /v1/keywords/related](https://datacircle.dev/related-keywords-apis/local-seo-data/top-up-from-5-pay-as-you-go-post-v1-keywords-related/llms.txt): $36.00 per 1,000, 50% complete
- [Ahrefs, $129 monthly, Lite, GET /v3/keywords-explorer/related-terms, Related terms, full](https://datacircle.dev/related-keywords-apis/ahrefs/129-monthly-lite-get-v3-keywords-explorer-related-terms-related-terms-full/llms.txt): $44.505 per 1,000, 50% complete
- [SEOZoom, €99 monthly](https://datacircle.dev/related-keywords-apis/seozoom/99-monthly/llms.txt): $1,485.396 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 2026-11-12.

- https://signalsumo.com/api-docs?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://signalsumo.com/page/terms-of-use?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://signalsumo.com/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing