# TheKeyword, free: Related keywords API

> Every analysis includes available SERP data, related keywords and metrics at no extra cost.

TheKeyword's Free plan for the related keywords API costs $0.00 per 1,000 keywords. TheKeyword's docs list 1 of the 6 fields on our checklist: Search volume.
We haven't run TheKeyword through [our related keywords API benchmark](https://datacircle.dev/best-related-keywords-api.txt) yet.
This plan is free. We rank 226 plans for related keywords APIs by price. Half the plans cost $0.596 per 1,000 keywords or less. [See the best free related keywords API plan.](https://datacircle.dev/best-related-keywords-api.txt)
[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.
[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.
[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/thekeyword/free
- [Related keywords API: the 9 best providers compared](https://datacircle.dev/best-related-keywords-api.txt)
- Get it: https://thekeyword.io/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Request: `GET https://api.thekeyword.io/api/v1/keywords/{slug}/related`
- API key: with the plan, on https://thekeyword.io/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- Its API docs: https://github.com/andginja/keywordskills/blob/main/skills/keyword-lookup/SKILL.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing#related-endpoints
- Sold by: TheKeyword (https://thekeyword.io?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing)
- Checked: 2026-11-07

## In the answer

- Completeness: 17%
- Search volume: ✓

## Price

- $ per 1,000 keywords: $0.00
- Per: page, size not stated
- Billing: free

## Charges

- Start fee: $0.00
- Also pays for: from the same budget: Single Keyword Analysis

## Overage

- Units cap: hard

## Not found

- $ per 1,000: $0.00

## In their words

- Their pitch: Every analysis includes available SERP data, related keywords and metrics at no extra cost.

## Data

- Freshness: stored
- Keep data: no limit
- Use data: Terms of Service, 4. Acceptable Use: "You agree not to: Share or resell API keys or data to third parties without authorization, Attempt to circumvent rate limits or usage quotas, Use the Service for any unlawful purpose, Reverse-engineer, scrape, or systematically download data beyond your plan limits, Interfere with the Service's infrastructure or other users' access"

## Plan

- Pay: $0
- You get: 3 credits a month
- Enough for: 3 pages a month

## Rate limit

- Batch: 1

## Speed

- Answer: in the call

## The call

- You send: slug. Optional: geo
- Method: GET
- Path: /api/v1/keywords/{slug}/related

## About the plan

- Plan: Free
- Who can get it: anyone at least 18 years old, one free account per person or entity

## The 2 fields the plan's answer can hold

keyword, search volume

## TheKeyword's plans (5)

- [TheKeyword, free](https://datacircle.dev/related-keywords-apis/thekeyword/free/llms.txt): $0.00 per 1,000, 17% complete, stored
- [TheKeyword, $19 monthly](https://datacircle.dev/related-keywords-apis/thekeyword/19-monthly/llms.txt): 17% complete, stored
- [TheKeyword, $49 monthly](https://datacircle.dev/related-keywords-apis/thekeyword/49-monthly/llms.txt): 17% complete, stored
- [TheKeyword, $149 monthly](https://datacircle.dev/related-keywords-apis/thekeyword/149-monthly/llms.txt): 17% complete, stored
- [TheKeyword, contact us](https://datacircle.dev/related-keywords-apis/thekeyword/contact-us/llms.txt): 17% complete, stored

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

- `GET /api/v1/keywords/{slug}/related`: [TheKeyword, free](https://datacircle.dev/related-keywords-apis/thekeyword/free/llms.txt)

## TheKeyword's APIs (2)

- [TheKeyword: keyword research API pricing, 5 plans](https://datacircle.dev/keyword-research-apis/thekeyword/free/llms.txt)
- [TheKeyword: related keywords API pricing, 5 plans](https://datacircle.dev/related-keywords-apis/thekeyword/free/llms.txt)

## TheKeyword: related keywords API alternatives

- [YepAPI, free credit, POST /v1/seo/keywords/ideas](https://datacircle.dev/related-keywords-apis/yepapi/free-credit-post-v1-seo-keywords-ideas/llms.txt): $0.00 per 1,000, 100% complete, stored
- [AnyAPI, free trial key, POST /v1/run/ahrefs.keyword_ideas](https://datacircle.dev/related-keywords-apis/anyapi/free-trial-key-post-v1-run-ahrefs-keyword-ideas/llms.txt): $0.00 per 1,000, 33% complete, stored
- [Alura, free](https://datacircle.dev/related-keywords-apis/alura/free/llms.txt): $0.00 per 1,000, 33% complete, stored
- [WordRadar, free](https://datacircle.dev/related-keywords-apis/wordradar/free/llms.txt): $0.00 per 1,000, 0% complete, stored

## Sources

From each provider's own pricing page and docs, and from what providers tell us. We read this row from these pages on 2026-11-07.

- https://raw.githubusercontent.com/andginja/keywordskills/main/skills/keyword-analysis/SKILL.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://raw.githubusercontent.com/andginja/keywordskills/main/skills/keyword-lookup/SKILL.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://raw.githubusercontent.com/andginja/keywordskills/main/skills/thekeyword-setup/SKILL.md?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://thekeyword.io?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://thekeyword.io/pricing?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing
- https://thekeyword.io/terms?utm_source=datacircle.dev&utm_medium=referral&utm_campaign=related-keywords-api-pricing