MLB Starting Lineups & Probable Pitchers API + Change Alerts

Get today's MLB starting lineups and probable pitchers as clean, normalized JSON — plus automatic change alerts every time you run it. This actor is a scheduled-run-friendly mlb lineups api: it fetches the daily MLB schedule (hydrated with probable pitchers and posted lineups), emits one row per game, and diffs against the previous run's snapshot to detect:

• 🔁 Probable pitcher changed (scratches, swaps)
• 📋 Lineup first posted (the moment a starting lineup drops)
• 🔀 Lineup player changed (late swaps, batting-order changes)

Perfect for fantasy baseball tools, DFS pipelines, betting models, Discord/Slack bots, and anyone searching for an mlb starting lineup api, probable pitchers api, or mlb lineup alerts feed without scraping.

How it works

1. Fetches the MLB StatsAPI daily schedule for today (plus optional days_ahead extra days).
2. Emits one lineup-row per game: teams, status, probable pitchers, and full home/away starting lineups (with batting order and positions) when posted. Before lineups are posted, home_lineup/away_lineup are empty arrays and lineups_posted is false — that's normal pre-game.
3. Diffs each game against the previous run's snapshot (stored per-game in the named key-value store mlb-lineups-snapshots) and emits change-alert rows.
4. Optionally POSTs alerts to your webhook_url.

Run it on a schedule (e.g. every 10–15 minutes on game days) to catch lineups the moment they're posted and pitchers the moment they're scratched.

Input

All fields optional — {} works out of the box.

Field	Type	Default	Description
days_ahead	integer	0	Extra days of schedule beyond today (max 7).
webhook_url	string	""	If set, alerts are POSTed there as {"alerts": [...]}.
include_unchanged	boolean	true	When false, only change-alert rows are pushed (alert-only mode).

Output

lineup-row (one per game)

{
  "type": "lineup-row",
  "gamePk": 823337,
  "game_date": "2026-09-03T16:35:00Z",
  "status": "Scheduled",
  "home_team": "Pittsburgh Pirates",
  "away_team": "San Francisco Giants",
  "home_probable_pitcher": { "id": 669199, "name": "Lake Bachar" },
  "away_probable_pitcher": { "id": 694918, "name": "Blade Tidwell" },
  "home_lineup": [
    { "id": 699302, "name": "Héctor Rodríguez", "position": "RF", "batting_order": 1 }
  ],
  "away_lineup": [],
  "lineups_posted": false,
  "fetched_at": "2026-09-03T02:55:41Z"
}

change-alert (one per detected change)

{
  "type": "change-alert",
  "gamePk": 822853,
  "change_kind": "probable_pitcher_changed",
  "field": "home_probable_pitcher",
  "old_value": "Old Guy",
  "new_value": "Cal Quantrill",
  "detected_at": "2026-09-03T02:56:08Z"
}

change_kind values: probable_pitcher_changed, lineup_posted, lineup_player_changed. For lineup_posted, new_value is a human-readable batting order (["1. Player (RF)", ...]); for player changes, field includes the batting slot (e.g. home_lineup[3]).

The first time a game is seen, it seeds the baseline — alerts start from the second run onward.

Pricing (pay per event)

• lineup-row — one normalized game row pushed
• change-alert — one detected change pushed

Notes & attribution

• Off-days / offseason: zero games is handled gracefully (nothing pushed).
• This actor is unofficial and not affiliated with, endorsed by, or sponsored by MLB. Data is sourced from the public MLB StatsAPI and is subject to MLB's terms: data © MLB Advanced Media, L.P. ("Copyright 2026 MLB Advanced Media, L.P. Use of any content on this page acknowledges agreement to the terms posted at http://gdx.mlb.com/components/copyright.txt"). Use for personal, non-commercial informational purposes per MLBAM's notice.