# Best related keywords API in 2026

> [Mangools](https://datacircle.dev/related-keywords-apis/mangools/15-monthly), [DataForSEO](https://datacircle.dev/related-keywords-apis/dataforseo/top-up-from-50-pay-as-you-go-post-v3-dataforseo-labs-google-keyword-ideas-live) and [SE Ranking](https://datacircle.dev/related-keywords-apis/se-ranking/29-monthly-add-on-monthly-billing-get-v1-keywords-similar) are the best related keywords API providers in our benchmark. We benchmarked 3 providers. We list all three, ranked by score. For each one, we show its top scoring plan, each part of the plan's score and what 1,000 keywords cost. We rank 53 plans by price. [Mangools's $15 monthly plan](https://datacircle.dev/related-keywords-apis/mangools/15-monthly) costs the least per 1,000 keywords: $0.0001. Mangools charges for each page of results. We count 10,000 keywords on each page to get the $0.0001 price.

1. [Mangools, $15 monthly: Related keywords API](https://datacircle.dev/related-keywords-apis/mangools/15-monthly): Overall score 92.5 (Price 88, Data 100, Cost to get started 87, Bundle 88, Performance N/A), $0.0001 per 1,000 keywords
   - It returns 5 of the 6 key fields we check: Search volume, Monthly trend, Cost per click, Competition, Keyword difficulty.
   - On 29 October 2026, we sent this provider the same 20 seeds as every other provider in our benchmark.
   - This plan scored 1 out of 1 on those 20 seeds. That gives this plan a Data score of 100 out of 100.
2. [DataForSEO, top-up from $50, Pay as you go: Related keywords API](https://datacircle.dev/related-keywords-apis/dataforseo/top-up-from-50-pay-as-you-go-post-v3-dataforseo-labs-google-keyword-ideas-live): Overall score 70.9 (Price 63, Data 88, Cost to get started 82, Bundle 92, Performance 4), $0.12 per 1,000 keywords
   - It returns all 6 key fields we check: Search volume, Monthly trend, Cost per click, Competition, Keyword difficulty, Search intent.
   - On 29 October 2026, we sent this provider the same 20 seeds as every other provider in our benchmark.
   - This plan scored 0.8784 out of 1 on those 20 seeds. That gives this plan a Data score of 88 out of 100.
3. [SE Ranking, $29 monthly, Add-on, monthly billing: Related keywords API](https://datacircle.dev/related-keywords-apis/se-ranking/29-monthly-add-on-monthly-billing-get-v1-keywords-similar): Overall score 36.1 (Price 32, Data 21, Cost to get started 82, Bundle 86, Performance 14), $1.933 per 1,000 keywords
   - It returns 5 of the 6 key fields we check: Search volume, Monthly trend, Cost per click, Competition, Keyword difficulty.
   - On 29 October 2026, we sent this provider the same 20 seeds as every other provider in our benchmark.
   - This plan scored 0.2142 out of 1 on those 20 seeds. That gives this plan a Data score of 21 out of 100.

The Data score on related keywords APIs: This score, out of 100, tells you how many keywords related to a seed keyword a provider's call returns. We ask for the keywords related to each seed keyword, in the United States and in English. For each seed, we count up to 100 of the keywords the provider's call returned. We count them out of 100. If every call sent fewer than 100 keywords, we count out of the largest number sent. We check how many keywords have each field, such as the search volume and the cost per click. We score each field against the highest count any provider got on that seed. A live call is scored only against live calls. We average the scores over all seeds. Each seed counts the same. A seed with no keyword in the answer counts as 0. We compare a provider that ran on fewer seeds with the other providers on those same seeds. A provider can't score higher by running only on easy seeds. We lower the score when we test the call on fewer seeds than the benchmark has.

Last updated: October 29, 2026. The page: https://datacircle.dev/best-related-keywords-api. Every plan: https://datacircle.dev/related-keywords-api-pricing. The benchmark: https://datacircle.dev/related-keywords-api-pricing/benchmark.csv.