Product-Led Growth (PLG) platforms instrument the self-serve product experience to surface sales-ready signals — identifying which free or trial users are hitting activation milestones, expansion triggers, or upgrade-readiness thresholds that warrant sales outreach. Core capabilities include product usage tracking and user segmentation, product-qualified lead (PQL) scoring, sales alert triggers based on usage milestones, account-level usage aggregation, in-product nudges and upgrade prompts, and integration with CRM, billing, and product analytics systems. The category spans dedicated PLG platforms (Pocus, Correlated, Calixa, Endgame) and PLG features within broader revenue intelligence tools.