balldontlie is a developer-facing sports-data API that first earned a reputation for being free, easy, and key-less for pulling NBA data. It has since expanded to NBA, WNBA, NFL, MLB, NHL, EPL, and 20+ leagues, and moved to an API-key, tiered-subscription model. The base URL is https://api.balldontlie.io/v1/, and auth is minimal: every request carries one HTTP header, `Authorization: YOUR_API_KEY` — no OAuth, no signing. NBA coverage is broad: Teams, Players, Games, Game Player Stats, Season Averages, Team Season Averages, Game Advanced Stats (v1/v2), Box Scores (live and historical), Lineups, Plays (play-by-play), Player Injuries, Standings, Leaders, Betting Odds, Player Props, and Contracts. These endpoints unlock progressively by tier: the free tier ($0, 5 req/min) exposes only Teams / Players / Games; All-Star ($9.99/mo, 60 req/min) adds Game Player Stats, Active Players, and Player Injuries; GOAT ($39.99/mo, 600 req/min) unlocks everything, including season averages, advanced stats, box scores, lineups, play-by-play, standings, leaders, odds, player props, and contracts. The top All-Access tier ($299.99/mo, 600 req/min) is the only one spanning every sport — the rest are billed per sport, so an NBA + NFL product means either two GOAT subscriptions or a jump to All-Access, a fairly steep cost step. Against the official stats.nba.com (undocumented, key-less, prone to 429s or breaking changes), balldontlie’s value is stability, public pricing, and simple auth — ideal for indie developers and small teams getting started quickly. Against API-Sports (API-NBA), balldontlie meters per minute rather than per day, so the free tier’s 5 req/min is really only enough for debugging; production should start at All-Star. Two common gotchas: first, many assume the free tier returns scores and player data, but it has no box scores at all and per-game player stats need at least All-Star; second, limits are per-minute, so any polling loop must throttle or it will hit 429s immediately.