# Seonio, free: Related keywords API

> Up to 100 related keyword ideas — each with full metrics — from one seed keyword.

Seonio's related keywords API on its Free $1 plan. It costs $0.00 per 1,000 keywords. Seonio's docs list all 6 key fields we check: Search volume, Monthly trend, Cost per click, Competition, Keyword difficulty, Search intent.
We haven't run Seonio through [our related keywords API benchmark](https://datacircle.dev/best-related-keywords-api.txt) yet.
This plan is free. We rank 194 plans for related keywords APIs by price. Half the plans cost $0.60 per 1,000 keywords or less.
[Keys.so's ₽34,900 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 monthly plan charges nothing per call. You get as many keywords as Keys.so's rate limit allows.
[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 monthly plan.
[Bing Webmaster Tools](https://datacircle.dev/related-keywords-apis/bing-webmaster-tools/free/llms.txt), [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) and [Mangools](https://datacircle.dev/related-keywords-apis/mangools/15-monthly/llms.txt) are the best related keywords API providers in the Datacircle benchmark.

- This page: https://datacircle.dev/related-keywords-apis/seonio/free
- [Related keywords API: the 7 best providers compared](https://datacircle.dev/best-related-keywords-api.txt)
- Get it: https://seonio.com/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Request: `POST https://seonio.com/api/v1/keywords/suggestions`
- API key: with the plan, on https://seonio.com/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Its API docs: https://seonio.com/product/api/keywords/suggestions?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Sold by: Seonio (https://seonio.com?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing)
- Checked: 2026-11-06

## In the answer

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

## Price

- $ per 1,000 keywords: $0.00
- Per: page of 100
- Billing: free

## Charges

- Also pays for: from the same budget: Keyword Research · Keyword Difficulty · Keyword Intent · Keyword Demographics · Keyword Clustering · Keyword Metrics by Country · SERP · SERP Scraper · Scraper · Website Traffic · Website Ranking · Website Category · Website Competitors · Similar Websites · URL Stats · URL Keywords · Website Stats · Backlink History · Backlink Table · AI Visibility Report · AI Visibility Result · Site Audit · Site Audit Result · Seonio SEO Agent · SEO Page Checker

## Overage

- Units cap: hard

## Not found

- $ per 1,000: $0.00

## In their words

- Their pitch: Up to 100 related keyword ideas — each with full metrics — from one seed keyword.

## Data

- Keep data: no limit
- Use data: [...] you may use reports, API responses, and outputs generated through your account for: your internal business purposes, your own websites, products, applications, and projects, client work performed by you or your organization, integrations that use Seonio data as part of a broader product or workflow, provided that you comply with these Terms and applicable law [...] You must not: resell standalone access to Seonio, resell or sublicense API access, API keys, or your account, resell raw datasets, raw API responses, or raw outputs as a separate data product, use the Service or outputs to build a substantially similar competing service without our written permission, misrepresent Seonio outputs as official, guaranteed, real-time, or independently verified data, remove or obscure any usage restrictions, source notices, or attribution requirements that may be shown in the Service

## Plan

- Pay: $0
- You get: $1
- Enough for: 50 pages, once
- Expires: 30 days after the account is verified

## Rate limit

- Per second: 5
- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: keyword. Optional: country
- Method: POST
- Path: /api/v1/keywords/suggestions

## About the plan

- Plan: Free $1
- Who can get it: anyone with a verified account

## The 11 fields the plan's answer can hold

seed keyword, country code, keyword, search volume, cost per click, low top of page bid, high top of page bid, competition index, monthly searches, keyword difficulty, search intent

## Seonio's plans (10)

- [Seonio, free](https://datacircle.dev/related-keywords-apis/seonio/free/llms.txt): $0.00 per 1,000, 100% complete
- [Seonio, $10 pack](https://datacircle.dev/related-keywords-apis/seonio/10-pack/llms.txt): 100% complete
- [Seonio, $100 pack](https://datacircle.dev/related-keywords-apis/seonio/100-pack/llms.txt): $0.174 per 1,000, 100% complete
- [Seonio, $1,000 pack](https://datacircle.dev/related-keywords-apis/seonio/1000-pack/llms.txt): 100% complete
- [Seonio, $15 monthly](https://datacircle.dev/related-keywords-apis/seonio/15-monthly/llms.txt): $0.20 per 1,000, 100% complete
- [Seonio, $30 monthly](https://datacircle.dev/related-keywords-apis/seonio/30-monthly/llms.txt): $0.16 per 1,000, 100% complete
- [Seonio, $60 monthly](https://datacircle.dev/related-keywords-apis/seonio/60-monthly/llms.txt): $0.133 per 1,000, 100% complete
- [Seonio, $120 yearly](https://datacircle.dev/related-keywords-apis/seonio/120-yearly/llms.txt): $0.133 per 1,000, 100% complete
- [Seonio, $240 yearly](https://datacircle.dev/related-keywords-apis/seonio/240-yearly/llms.txt): $0.107 per 1,000, 100% complete
- [Seonio, $480 yearly](https://datacircle.dev/related-keywords-apis/seonio/480-yearly/llms.txt): $0.089 per 1,000, 100% complete

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

- `POST /api/v1/keywords/suggestions`: [Seonio, free](https://datacircle.dev/related-keywords-apis/seonio/free/llms.txt)

## Seonio's APIs (8)

- [Seonio: related keywords API pricing, 10 plans](https://datacircle.dev/related-keywords-apis/seonio/free/llms.txt)
- [Seonio: backlink API pricing, 10 plans](https://datacircle.dev/backlink-apis/seonio/free/llms.txt)
- [Seonio: web scraping API pricing, 10 plans](https://datacircle.dev/web-scraping-apis/seonio/free/llms.txt)
- [Seonio: keyword research API pricing, 10 plans, POST /api/v1/keywords/country](https://datacircle.dev/keyword-research-apis/seonio/free-1-post-api-v1-keywords-country/llms.txt)
- [Seonio: keyword research API pricing, 10 plans, POST /api/v1/keywords/global](https://datacircle.dev/keyword-research-apis/seonio/free-1-post-api-v1-keywords-global/llms.txt)
- [Seonio: SERP API pricing, 10 plans, POST /api/v1/serp/country](https://datacircle.dev/serp-apis/seonio/free-1-post-api-v1-serp-country/llms.txt)
- [Seonio: SERP API pricing, 10 plans, POST /api/v1/serp/scraper](https://datacircle.dev/serp-apis/seonio/free-1-post-api-v1-serp-scraper/llms.txt)
- [Seonio: similar companies API pricing, 10 plans, POST /api/v1/website/similar](https://datacircle.dev/similar-company-apis/seonio/free-1-post-api-v1-website-similar/llms.txt)
- [Seonio: similar companies API pricing, 10 plans, POST /api/v1/website/competitors](https://datacircle.dev/similar-company-apis/seonio/free-1-post-api-v1-website-competitors/llms.txt)
- [Seonio: ranked keywords API pricing, 10 plans, POST /api/v1/url/keywords](https://datacircle.dev/ranked-keywords-apis/seonio/free-1-post-api-v1-url-keywords/llms.txt)
- [Seonio: ranked keywords API pricing, 10 plans, POST /api/v1/website/ranking](https://datacircle.dev/ranked-keywords-apis/seonio/free-1-post-api-v1-website-ranking/llms.txt)
- [Seonio: domain authority API pricing, 10 plans, POST /api/v1/url/stats](https://datacircle.dev/domain-authority-apis/seonio/free-1-post-api-v1-url-stats/llms.txt)
- [Seonio: domain authority API pricing, 10 plans, POST /api/v1/website/stats](https://datacircle.dev/domain-authority-apis/seonio/free-1-post-api-v1-website-stats/llms.txt)

## Seonio: related keywords API alternatives

- [Wordtracker, $60 monthly](https://datacircle.dev/related-keywords-apis/wordtracker/60-monthly/llms.txt): $0.06 per 1,000, 33% complete
- [KeywordTool.io, $788 monthly, Agency, GET /v2/search/suggestions/google](https://datacircle.dev/related-keywords-apis/keywordtool-io/788-monthly-agency-get-v2-search-suggestions-google/llms.txt): $0.066 per 1,000, 67% complete
- [SpyWords, ₽10,000 monthly](https://datacircle.dev/related-keywords-apis/spywords/10000-monthly/llms.txt): $0.119 per 1,000, 33% complete
- [DataForSEO, top-up from $50, Pay as you go, POST /v3/dataforseo_labs/google/keyword_ideas/live](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): $0.12 per 1,000, 100% complete, 1 month

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-11-06.

- https://seonio.com/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://seonio.com/product/api?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://seonio.com/product/api/keywords/suggestions?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://seonio.com/terms?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing