SEO keyword work splits into two numbers. Keyword Planner and the Google Ads Keyword Planning API answer how many searches a month, as a range unless the ads account spends. Trends API answers whether interest is rising, falling, or seasonal. POST https://api.trendsapi.ai/api with source google search. Request fields are on the API reference. Treat the returned body as quoted JSON, not as the series itself. Property filters for Google live on the Google Trends guide.
Slope is a get_growth row
POST https://api.trendsapi.ai/api
Authorization: Bearer <api_key>
Content-Type: application/json
{"mode":"get_growth","source":"google search","keyword":"air fryer","percent_growth":["3M","12M"]}
Checked 27 Aug 2026: air fryer on google search was 56 (22 Aug 2026). The quarter print was −18.84%. The year print was +16.67%. A brief that only cites the year still ships into a cooling quarter. Google's own Keyword Planner notes say avg_monthly_searches is a 12-month average and can miss a spike. The 3M row is the check that average hides.
Seasonality is get_time_series
get_time_series with the same source and keyword returns an array of {date, value, keyword, source} points. That is the chart for a recurring brief (tax software in January, air fryer ahead of holidays). Do not average the series into one cell and call it volume. Search Console remains the first-party query list for a property that already ranks. This POST is the market series for a term the property does not own yet.
News and YouTube are not the SERP
google news and youtube accept the same phrase. They measure press and video search. A newsroom spike can lift google news while the web SERP the SEO page will enter stays flat. Keep those sources on a second tab. The live board type Google Trends is a third object: no keyword, ranked terms for the snapshot. lunar eclipse august 2026 sat at rank 6 on 27 Aug 2026. That is a dated event, not a pillar URL.