Yahoo Fantasy Baseball API Reader

Want to download your fantasy baseball data from Yahoo but having a hard time interfacing with their poorly documented API?

This tool is for you.

• Installation
• Usage
• Yahoo's API docs

Also, this is written in NodeJS. Tested and updated for the 2026 season.

Installation

Part 1: Get access codes from Yahoo

1. Log into Yahoo
2. Navigate to https://developer.yahoo.com/apps/create/
3. Fill out the form
   • Application Name (Whatever)
   • Description (Whatever)
   • Homepage URL (anything, e.g. www.github.com)
   • Redirect URI(s) (anything, e.g. www.github.com)
   • API Permissions (checkmark Fantasy Sports, then Read/Write)
   • 
4. Create App
5. Yahoo will give you 3 values. Write down the last two:
   • App ID (don't care)
   • Client ID/Consumer Key
   • Client Secret/Consumer Secret
   • 
6. However the above codes are not enough to interface with the Yahoo Fantasy API. Take the Client ID/Consumer Key from above and paste it into the following URL:

https://api.login.yahoo.com/oauth2/request_auth?client_id=YOUR-CLIENT-ID-GOES-HERE&redirect_uri=oob&response_type=code&language=en-us

7. Enter that URL into your browser.
8. Agree to allow access for your app.

• 

9. Grab the code Yahoo now gives you.

• 

Part 2: Configure this app

10. Install NodeJS (Check the .nvmrc file for version but most versions should work)
11. Clone this repo
12. In the repo directory type npm install
13. Optional: To make sure you're using the right version NodeJS, type in nvm use. If you get an error message that nvm cannot be found, install it (e.g. Mac) and try again
14. Rename config.json.example to config.json and open it in a text editor
15. Enter in the following values and save:
    • CONSUMER_KEY: Obtained from Yahoo in step 5 above
    • CONSUMER_SECRET: Also obtained from Yahoo in step 5 above
    • YAHOO_AUTH_CODE: Obtained from Yahoo in step 9 above (not the App ID in step 5!)
    • LEAGUE_KEY: the League Key has three parts:
      • (1) a unique prefix Yahoo randomly assigns each season
      • (2) the string ".l." (that's a lowercase L)
      • (3) the unique ID of your league
      • E.g.: 469.l.123456
      • To find out this number:
        • If it's 2026 and baseball, the unique prefix for MLB is 469.
        • You can find out the league prefix by running:

        nvm use
        (if necessary install the appopriate version of node)
        npm install
        npm start
        npm run league-prefix
        

        • You can find your league ID simply by logging into the Yahoo Fantasy Baseball website - it'll be the value after https://baseball.fantasysports.yahoo.com/b1/
        • Combine those two with ".l." for a final format of 412.l.123456
    • TEAM: This is your team number.
      • Just log into the Yahoo Fantasy Baseball website, click on "My Team", then check the URL to see what team number you are. Usually 1-8
    • AUTH_FILE: Where to store the credentials. Can be anything you want.
    • FREE_AGENTS: How many "pages" of free agents to request from Yahoo, 25 at a time. E.g. 0 = first 25 free agents by rank in the league, 1 = 50, 2 = 75, etc.

Usage

Run the app

Navigate to the repo directory and run:

> npm run start

By default this app will pull in the following data:

const allData = {
    "free agents": freeAgents, 
    "my players": myPlayers, 
    "my players' stats": myPlayersStats, 
    "my scoreboard": myScoreboard, 
    "stat IDs": statsIDs, 
    "current roster": currentRoster, 
    "transactions": transactions
};

And write this JSON object to a file, allMyData.json. From there you should be able to consume and manipulate your data.

This may or may not include your desired data set, but you should be able to use this template to pull in whatever you want. The Yahoo API docs are not great so I've summarized them below.

Yahoo Fantasy API Docs

Overview of Endpoints/Resources

There's Yahoo's official guide but it's not great. All of the info below is from their website, just more organized.

First, an overview of the "Resources" (aka endpoints) Yahoo makes available:

• Player
  • Player stats & info, docs
• Game
  • individual game data, docs
• League
  • info about your league, docs
• Team
  • stats, standings and roster info about your team, docs
• Roster
  • manage your roster, docs
• Transaction
  • monitor or make transactions, docs
• User
  • info about the Yahoo user, docs

Except for "Roster", all other 6 endpoints also offer groups of items called "Collections" (instead of "Resources"). Basically the same content, just more than one item at a time.

Subresouces

Each endpoint has subresources that can be accessed:

Base URL

For all the links below, the base URL is https://fantasysports.yahooapis.com/fantasy/v2

Player subresources

• With the Player API, you can obtain the player (athlete) related information, such as their name, professional team, and eligible positions.
• E.g. https://fantasysports.yahooapis.com/fantasy/v2/league/223.l.431/players;player_keys=223.p.5479

Name	Description	URI	Sample
metadata	Includes player key, id, name, editorial information, image, eligible positions, etc.	/fantasy/v2/player/{player_key}/metadata	Drew Brees's info in the 2009 season: /player/223.p.5479
stats	Player stats and points (if in a league context).	Season stats: /fantasy/v2/player/{player_key}/stats Week stats: /fantasy/v2/player/{player_key}/stats;type=week;week={week} Here {week} is a non-zero integer.	Drew Brees's info and stats in the 2009 season: /player/223.p.5479/stats
ownership	The player ownership status within a league (whether they're owned by a team, on waivers, or free agents). Only relevant within a league.	/fantasy/v2/league/{league_key}/players;player_keys={player_key}/ownership	/league/223.l.431/players;player_keys=223.p.5479/ownership
percent_owned	Data about ownership percentage of the player	/fantasy/v2/player/{player_key}/percent_owned	The percentage of leagues in which Drew Brees was owned in the 2009 game: /player/223.p.5479/percent_owned
draft_analysis	Average pick, Average round and Percent Drafted.	/fantasy/v2/player/{player_key}/draft_analysis	Yahoo! fantasy draft information for Drew Brees in 2009: /player/223.p.5479/draft_analysis

Player collection

• "With the Players API, you can obtain information from a collection of players simultaneously."
• /players;player_keys={player_key1},{player_key2};out={sub_resource_1},{sub_resource_2}

Player filters

Filter parameter	Filter parameter values	Usage
position	Valid player positions	/players;position=QB (Note: Applied only in a league's context)
status	A (all available players), FA (free agents only), W (waivers only), T (all taken players), K (keepers only)	/players;status=A (Note: Applied only in a league's context)
search	player name	/players;search=smith (Note: Applied only in a league's context)
sort	{stat_id}, NAME (last, first), OR (overall rank), AR (actual rank), PTS (fantasy points)	/players;sort=60 (Note: Applied only in a league's context)
sort_type	season, date (baseball, basketball, and hockey only), week (football only), lastweek (baseball, basketball, and hockey only), lastmonth	/players;sort_type=season (Note: Applied only in a league's context)
sort_season	year	/players;sort_type=season;sort_season=2010 (Note: Applied only in a league's context)
sort_date (baseball, basketball, and hockey only)	YYYY-MM-DD	/players;sort_type=date;sort_date=2010-02-01 (Note: Applied only in a league's context)
sort_week (football only)	week	/players;sort_type=week;sort_week=10
start	Any integer 0 or greater	/players;start=25 (Note: Applied only in a league's context)
count	Any integer b/t 0 & 25	/players;count=5 (Note: Applied only in a league's context)

Game subresources

• With the Game API, you can obtain the fantasy game related information, like the fantasy game name, the Yahoo! game code, and season.
• E.g. /game/{game_key}/{sub_resource}

Name	Description	URI	Sample
metadata	Includes game key, code, name, url, type and season.	/fantasy/v2/game/{game_key}/metadata	The 2009 Football PLUS game: /game/223
leagues	Fetch specified leagues under a game.	/fantasy/v2/game/{game_key}/leagues;league_keys={league_key1},{league_key2}	A publicly viewable league within the 2009 football plus game: /game/223/leagues;league_keys=223.l.431
players	Fetch specified players under a game.	/fantasy/v2/game/{game_key}/players;player_keys={player_key1},{player_key2}	Brett Favre's information from the 2009 football plus game: /game/223/players;player_keys=223.p.1025
game_weeks	Start and end date information for each week in the game	/fantasy/v2/game/{game_key}/game_weeks	NFL game weeks /game/nfl/game_weeks
stat_categories	Detailed description of all available stat categories for the game.	/fantasy/v2/game/{game_key}/stat_categories	NFL stat categories /game/nfl/stat_categories
position_types	Detailed description of all player position types for the game.	/fantasy/v2/game/{game_key}/position_types	NFL position types /game/nfl/position_types
roster_positions	Detailed description of all roster positions for the game.	/fantasy/v2/game/{game_key}/roster_positions	NFL roster positions /game/nfl/roster_positions

Games collection

• With the Games API, you can obtain information from a collection of games simultaneously. Each element beneath the Games Collection will be a Game Resource
• E.g. https://fantasysports.yahooapis.com/fantasy/v2/games;game_keys={game_key1},{game_key2};out={sub_resource_1},{sub_resource_2}

Games filters

Filter parameter	Filter parameter values	Usage
is_available	1 to only show games currently in season	/games;is_available=1
game_types	full	pickem-team
game_codes	Any valid game codes	/games;game_codes=nfl,mlb
seasons	Any valid seasons	/games;seasons=2011,2012

League subresources

• With the League API, you can obtain the league related information, like the league name, the number of teams, the draft status, et cetera.
• E.g. https://fantasysports.yahooapis.com/fantasy/v2/league/223.l.431

Name	Description	URI	Sample
metadata	Includes league key, id, name, url, draft status, number of teams, and current week information.	/fantasy/v2/league/{league_key}/metadata	/league/223.l.431
settings	League settings. For instance, draft type, scoring type, roster positions, stat categories and modifiers, divisions.	/fantasy/v2/league/{league_key}/settings	/league/223.l.431/settings
standings	Ranking of teams within the league. Accepts Teams as a sub-resource, and includes team_standings data by default beneath the teams	/fantasy/v2/league/{league_key}/standings	/league/223.l.431/standings
scoreboard	League scoreboard. Accepts Matchups as a sub-resource, which in turn accept Teams as a sub-resource. Includes team_stats data by default.	Scoreboard for current week: /fantasy/v2/league/{league_key}/scoreboard	Scoreboard for a particular week: /fantasy/v2/league/{league_key}/scoreboard;week={week}
teams	All teams in the league.	/fantasy/v2/league/{league_key}/teams	/league/223.l.431/teams
players	The league's eligible players.	/fantasy/v2/league/{league_key}/players	/league/223.l.431/players
draftresults	Draft results for all teams in the league.	/fantasy/v2/league/{league_key}/draftresults	/league/223.l.431/draftresults
transactions	League transactions -- adds, drops, and trades.	/fantasy/v2/league/{league_key}/transactions	/league/223.l.431/transactions

Leagues collection

• With the Leagues API, you can obtain information from a collection of leagues simultaneously.
• /leagues;league_keys={league_key1},{league_key2}/{sub_resource}

Team subresources

• The Team APIs allow you to retrieve information about a team within our fantasy games.
• E.g. https://fantasysports.yahooapis.com/fantasy/v2/team/223.l.431.t.1

Name	Description	URI	Sample
metadata	Includes team key, id, name, url, division ID, logos, and team manager information.	/fantasy/v2/team/{team_key}/metadata	/team/223.l.431.t.9
stats	Team statistical data and points.	Season stats: /fantasy/v2/team/{team_key}/stats Week stats: /fantasy/v2/team/{team_key}/stats;type=week;week={week} Here {week} is a non-zero integer, or current for the current week.	/team/223.l.431.t.9/stats;type=week;week=2
standings	Team rank, wins, losses, ties, and winning percentage (as well as divisional data if applicable).	/fantasy/v2/team/{team_key}/standings	/team/223.l.431.t.9/standings
roster	Team roster. Accepts a week parameter. Also accepts Players as a sub-resource (included by default)	Roster for a particular week: /fantasy/v2/team/{team_key}/roster;week={week} Here {week} is a non-zero integer. If week is current, or isn't provided, defaults to current week.	/team/223.l.431.t.9/roster;week=2 - The week 2 roster for team 223.l.431.t.9
draftresults	List of players drafted by the team.	/fantasy/v2/team/{team_key}/draftresults	/team/223.l.431.t.9/draftresults
matchups	All the matchups this team has scheduled (for H2H leagues).	All matchups: /fantasy/v2/team/{team_key}/matchups Particular weeks: /fantasy/v2/team/{team_key}/matchups;weeks=1,3,6	/team/223.l.431.t.9/matchups;weeks=1,3,6

Teams collection

• With the Teams API, you can obtain information from a collection of teams simultaneously.
• /teams;team_keys={team_key1},{team_key2};out={sub_resource_1},{sub_resource_2}

Roster subresources

• You can use this API to edit your lineup by PUTting up new positions for the players on a roster.
• https://fantasysports.yahooapis.com/fantasy/v2/team//roster;date=2011-05-01

Name	Description	URI	Sample
players	Access the players collection within the roster.	/fantasy/v2/team/{team_key}/roster/players	/team/223.l.431.t.9/roster/players

Transaction subresources

• With the Transaction API, you can obtain information about transactions (adds, drops, trades, and league settings changes) performed on a league
• E.g. https://fantasysports.yahooapis.com/fantasy/v2/transaction/257.l.193.tr.2

Name	Description	URI	Sample
metadata	Includes transaction key, id, type, timestamp, status, players (not displayed for all transaction types)	/fantasy/v2/transaction/{transaction_key}/metadata	An add/drop transaction: /transaction/223.l.431.tr.26
players	Players that are part of the transaction. The Player Resources will include a transaction data element by default.	/fantasy/v2/transaction/{transaction_key}/players	/transaction/223.l.431.tr.26/players

Transaction collection

• With the Transactions API, you can obtain information via GET from a collection of transactions simultaneously.
• E.g. /transactions;transaction_keys={transaction_key1},{transaction_key2};out={sub_resource_1},{sub_resource_2}

Transaction filters

Filter parameter	Filter parameter values	Usage
type	add,drop,commish,trade	/transactions;type=add
types	Any valid types	/transactions;types=add,trade
team_key	A team_key within the league	/transactions;team_key=257.l.193.t.1
type with team_key	waiver,pending_trade	You can only use these options when also providing the team_key, ie /transactions;team_key=257.l.193.t.1;type=waiver
count	Any integer greater than 0	/transactions;count=5

User subresources

• With the User API, you can retrieve fantasy information for a particular Yahoo! user. It is generally recommended that you instead use the Users collection, passing along the use_login flag.

Name	Description	URI	Sample
games	Fetch the Games in which the user has played. Additionally accepts flags is_available to only return available games.	/fantasy/v2/users;use_login=1/games	/users;use_login=1/games
games/leagues	Fetch leagues that the user belongs to in one or more games. The leagues will be scoped to the user. This will throw an error if any of the specified games do not support league sub-resources.	/fantasy/v2/users;use_login=1/games;game_keys={game_key1},{game_key2}/leagues	/users;use_login=1/games;game_keys=223/leagues
games/teams	Fetch teams owned by the user in one or more games. The teams will be scoped to the user. This will throw an error if any of the specified games do not support team sub-resources.	/fantasy/v2/users;use_login=1/games;game_keys={game_key1},{game_key2}/teams

User resource/collection

• With the User API, you can retrieve fantasy information for a particular Yahoo! user. It is generally recommended that you instead use the Users collection, passing along the use_login flag.

Name	Description	URI	Sample
games	Fetch the Games in which the user has played. Additionally accepts flags is_available to only return available games.	/fantasy/v2/users;use_login=1/games	/users;use_login=1/games
games/leagues	Fetch leagues that the user belongs to in one or more games. The leagues will be scoped to the user. This will throw an error if any of the specified games do not support league sub-resources.	/fantasy/v2/users;use_login=1/games;game_keys={game_key1},{game_key2}/leagues	/users;use_login=1/games;game_keys=223/leagues
games/teams	Fetch teams owned by the user in one or more games. The teams will be scoped to the user. This will throw an error if any of the specified games do not support team sub-resources.	/fantasy/v2/users;use_login=1/games;game_keys={game_key1},{game_key2}/teams	/users;use_login=1/games;game_keys=223/teams