Underdog Fantasy

Underdog (Underdog Sports, formerly Underdog Fantasy) is a Brooklyn, New York based sports gaming company founded in 2020 by Jeremy Levine that operates daily fantasy sports, pick'em, and — since 2025 — federally regulated sports prediction markets on its own proprietary technology stack. Its consumer products include Classic Pick'em, Pick'em Champions, Best Ball and other Draft Games, Streaks, Team Picks, and the Underdog Predict prediction-markets exchange, delivered through iOS, Android, and web apps rather than a public developer API. Underdog reached roughly $500M in annual revenue within five years, was valued at $1.2B after a Spark Capital-led Series C in March 2025, acquired CFTC-registered derivatives infrastructure in March 2026, and in July 2026 was the subject of a proposed acquisition by IG Group. The company publishes no developer portal, API documentation, or machine-readable API contract; its public technical surface is limited to an RFC 9116 security.txt with a PGP key, a Honeybadger-hosted status page covering its API and Stats services, and the Underdog-Inc GitHub organization.

Underdog Fantasy is profiled on the APIs.io network. Tagged areas include Company, Sports, Fantasy Sports, Sports Betting, and Prediction Markets.

Underdog Fantasy’s developer surface includes signup flow, support, and 21 more developer resources.

🌐 Visit website 📡 Source on GitHub

12.1/100 emerging ▬ flat Agent 2/100 human only Full breakdown ↓
scored 2026-08-25 · rubric v0.14.0

0 APIs

Company Sports Fantasy Sports Sports Betting Prediction Markets Gaming Entertainment Consumer Mobile

Kin Score

Kin Score How this is scored →
scored 2026-08-25 · rubric v0.14.0

Composite quality — 12.1/100 · emerging

Contract Quality 0.0 / 25

Developer Ergonomics 1.0 / 20

Access Clarity 1.3 / 20

Operational Transparency 3.8 / 13

Contract Governance 0.0 / 12

Discoverability 6.1 / 10

Agent readiness — 2/100 · human only

Machine-Readable Contract 0 / 18

Agentic Access Contract 0 / 10

Documented Reversibility 0 / 6

MCP Server 0 / 12

Machine-Readable Auth 0 / 10

Idempotency 0 / 9

Stable Error Semantics 0 / 8

Request/Response Examples 0 / 7

Rate-Limit Signaling 0 / 7

Typed Event Surface 0 / 6

Agent Skills 0 / 5

Well-Known Catalog 0 / 4

Consent & Bot Identity 3 / 3

A2A Agent Card 0 / 8

Dry-Run / Simulate Mode 0 / 4

Delegated User Identity 0 / 6

Protected Resource Metadata 0 / 5

Registration Without a Human 0 / 6

Agentic Commerce Surface 0 / 5

Improve this rating by publishing the missing artifacts — every area above can be raised, and the full rubric is at apis.io/rating/. This rating is computed from github.com/api-evangelist/underdog-fantasy: open an issue to ask a question, or submit a pull request to add artifacts. Want it done for you? Prioritized profiling — $2,500 →

Get Started 2

Portal, sign-up, and the first successful call

SignUp

SignUp

Login

Agent Surfaces 2

MCP servers, agent skills, and machine-readable catalogs

WellKnown

WellKnown

LLMsTxt

LLMsTxt

Design & Contract 2

Pagination, idempotency, versioning, errors, and events

Lifecycle

Lifecycle

Rules

Rules

Build 2

SDKs, sample code, and the tooling you integrate with

GitHubOrganization

GitHubOrganization

Packages

Packages

Access & Security 4

Authentication, authorization, and security posture

Security

Security

SecurityTxt

SecurityTxt

VulnerabilityDisclosure

VulnerabilityDisclosure

DomainSecurity

DomainSecurity

Operate 2

Status, limits, changes, and where to get help

Support

Support

StatusPage

StatusPage

Commercial 2

Pricing, plans, and the legal terms of use

TermsOfService

TermsOfService

PrivacyPolicy

PrivacyPolicy

Company 4

The organization behind the API

Website

Website

Careers

Press

Other 3

Properties that don't map to a standard resource type

ResponsibleGaming

ResponsibleGaming

iOSApp

iOSApp

AndroidApp

AndroidApp

Source (apis.yml)

aid: underdog-fantasy
name: Underdog Fantasy
description: Underdog (Underdog Sports, formerly Underdog Fantasy) is a Brooklyn, New York based sports gaming company founded
  in 2020 by Jeremy Levine that operates daily fantasy sports, pick'em, and — since 2025 — federally regulated sports prediction
  markets on its own proprietary technology stack. Its consumer products include Classic Pick'em, Pick'em Champions, Best
  Ball and other Draft Games, Streaks, Team Picks, and the Underdog Predict prediction-markets exchange, delivered through
  iOS, Android, and web apps rather than a public developer API. Underdog reached roughly $500M in annual revenue within five
  years, was valued at $1.2B after a Spark Capital-led Series C in March 2025, acquired CFTC-registered derivatives infrastructure
  in March 2026, and in July 2026 was the subject of a proposed acquisition by IG Group. The company publishes no developer
  portal, API documentation, or machine-readable API contract; its public technical surface is limited to an RFC 9116 security.txt
  with a PGP key, a Honeybadger-hosted status page covering its API and Stats services, and the Underdog-Inc GitHub organization.
image: https://cdn.prod.website-files.com/67d86be30d981ef8b914a00d/67d86be30d981ef8b914a10f_big-fav.png
url: https://raw.githubusercontent.com/api-evangelist/underdog-fantasy/refs/heads/main/apis.yml
x-type: company
x-source: harvest:secondary-market
x-tier: profiled
x-tier-reason: enrichment-pass
specificationVersion: '0.23'
created: '2026-08-02'
modified: '2026-08-02'
tags:
- Company
- Sports
- Fantasy Sports
- Sports Betting
- Prediction Markets
- Gaming
- Entertainment
- Consumer
- Mobile
apis: []
maintainers:
- FN: Kin Lane
  email: kin@apievangelist.com
- FN: APIs.json
  email: info@apis.io
common:
- type: Website
  url: https://www.underdogsports.com/
- type: Website
  url: https://forgeglobal.com/underdog-fantasy_stock/
- type: SignUp
  url: https://app.underdogsports.com/register
- type: Login
  url: https://app.underdogsports.com/login
- type: Support
  url: https://help.underdogsports.com/en/
- type: TermsOfService
  url: https://legal.underdogsports.com/#terms-of-use
- type: PrivacyPolicy
  url: https://legal.underdogsports.com/#template-altl3g4-b
- type: StatusPage
  url: https://status.underdogfantasy.com/
- type: GitHubOrganization
  url: https://github.com/Underdog-Inc
- type: Security
  url: https://underdogfantasy.com/.well-known/security.txt
- type: SecurityTxt
  url: well-known/underdog-fantasy-security.txt
- type: WellKnown
  url: well-known/underdog-fantasy-well-known.yml
- type: VulnerabilityDisclosure
  url: security/underdog-fantasy-vulnerability-disclosure.yml
- type: DomainSecurity
  url: security/underdog-fantasy-domain-security.yml
- type: Lifecycle
  url: lifecycle/underdog-fantasy-lifecycle.yml
- type: Packages
  url: packages/underdog-fantasy-packages.yml
- type: LLMsTxt
  url: llms/underdog-fantasy-llms.txt
- type: Careers
  url: https://www.underdogsports.com/careers
- type: Press
  url: https://www.underdogsports.com/news
- type: Rules
  url: https://app.underdogsports.com/rules
- type: ResponsibleGaming
  url: https://www.underdogsports.com/responsible-gaming-resources
- type: iOSApp
  url: https://apps.apple.com/us/app/underdog-fantasy-sports/id1514665962
- type: AndroidApp
  url: https://play.google.com/store/apps/details?id=com.underdogsports.fantasy
x-enrichment:
  date: '2026-08-02'
  status: enriched
  artifacts_added: 8
  pass: local-v1

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