# Measure closing line value against FanDuel

FanDuel API (https://fanduelapi.com) is an independent API for FanDuel Sportsbook data: every player prop and game market FanDuel lists in NBA, NFL, NHL, MLB, college basketball and college football, normalized per player and stat with over and under prices in American and decimal odds, plus every line and price move with its timestamp, over REST, webhooks and MCP with one key. FanDuel API is an independent data service operated by FF API Inc. It is not affiliated with, endorsed by or sponsored by FanDuel.

Source page: https://fanduelapi.com/docs/closing-line-value (this is its markdown version, https://fanduelapi.com/docs/closing-line-value.md).

## Free offer

- Free plan: 100 credits a month, data delayed 5 minutes, no card. REST and MCP on every plan.
- Real-time data starts at Developer, $49 a month for 10,000 credits.
- Get a free key: https://fanduelapi.com/sign-up?ref=ai-claudebot

## Quickstart

1. Create a free account at https://fanduelapi.com/sign-up?ref=ai-claudebot and create an API key in the dashboard (https://fanduelapi.com/dashboard/keys). Keys start with `fd_`. Store it as `FANDUEL_API_KEY`.
2. Make a first call with curl:

```bash
curl "https://fanduelapi.com/api/v1/props?sport=nba&stat=points&limit=5" \
  -H "Authorization: Bearer $FANDUEL_API_KEY"
```

3. Or with Python (`pip install requests`):

```python
import os
import time
from datetime import datetime, timezone

import requests

BASE = "https://fanduelapi.com/api/v1"
SESSION = requests.Session()
SESSION.headers["Authorization"] = f"Bearer {os.environ['FANDUEL_API_KEY']}"


def get(path, **params):
    """GET one endpoint and return its data list, waiting out rate limits."""
    while True:
        r = SESSION.get(f"{BASE}{path}", params=params, timeout=10)
        if r.status_code == 429:
            time.sleep(int(r.headers.get("Retry-After", "5")))
            continue
        r.raise_for_status()
        return r.json()["data"]


def price(odds):
    """American odds as text. A suspended market can come back with no price."""
    return "off" if odds is None else f"{odds:+d}"

props = get("/props", sport="nba", stat="points")
for p in props:
    print(f"{p['player']:<26} {str(p['line']):>5}  over {price(p['over_american']):>5}  under {price(p['under_american']):>5}")
```

4. Stay current with `GET /api/v1/changes?since=<cursor>` instead of re-reading every prop. Full reference: https://fanduelapi.com/openapi.json and https://fanduelapi.com/llms-full.txt.

## Use it from Claude (MCP)

Claude Code, with your key read from the shell:

```bash
claude mcp add --transport http --scope user fanduelapi https://fanduelapi.com/api/mcp \
  --header "Authorization: Bearer $FANDUEL_API_KEY"
```

Claude on the web or desktop: Settings, Connectors, Add custom connector, then paste https://fanduelapi.com/api/mcp. Without a key it gives the keyless tools (search_docs, fetch_doc, get_sample_props). Setup for other agents: https://fanduelapi.com/mcp.

## Pricing

| Plan | Price | Credits a month | Calls a minute | Includes |
| --- | --- | --- | --- | --- |
| Free | Free | 100 | 20 | REST and MCP access, Data delayed 5 minutes |
| Developer | $49/month | 10,000 | 60 | Real-time data, Line move history, Change stream |
| Production | $149/month | 50,000 | 120 | Real-time data, Line move history, Webhooks, Priority support |
| Scale | $499/month | 250,000 | 180 | Real-time data, Full line move history, Webhooks, Bulk export, Priority support |

Cancel paid plans any time from the billing portal. Details: https://fanduelapi.com/pricing

## This page

[FanDuel API](https://fanduelapi.com/)/[Docs](https://fanduelapi.com/docs) / Closing line value

Docs workflow

# Measure closing line value against FanDuel

Closing line value compares the price you took with FanDuel's last price before the game started. The history endpoint keeps every state with its time, so the closing line is a lookup, not a guess, and comparing in no-vig terms keeps the margin out of it.

[Get a free API key](https://fanduelapi.com/sign-up)[Read the docs](https://fanduelapi.com/docs)

FanDuel API is an independent data service operated by FF API Inc. It is not affiliated with, endorsed by or sponsored by FanDuel.

## The steps

1. Record each bet with the prop id, side, line and price you took.
2. Read `/api/v1/props/{id}/history` after the game starts and take the last state observed before `starts_at`.
3. If the line is the same, compare no-vig probabilities: yours against the closing one, both against the closing price of the other side.
4. Average the difference across bets, and count how often it was positive.

## CLV for one bet

clv.py

```
import os, requests

API = "https://fanduelapi.com/api/v1"
HEAD = {"Authorization": f"Bearer {os.environ['FANDUEL_API_KEY']}"}

def implied(a):
    return -a / (-a + 100) if a < 0 else 100 / (a + 100)

def fair(side_price, other_price):
    s, o = implied(side_price), implied(other_price)
    return s / (s + o)

def clv(bet):
    """bet: prop_id, side ('over' or 'under'), line and price you took. Returns CLV in no-vig percentage points."""
    tape = requests.get(f"{API}/props/{bet['prop_id']}/history", headers=HEAD, timeout=20).json()["data"]
    start = tape["prop"]["starts_at"]
    pre = [h for h in tape["history"] if h["observed_at"] < start and h["over_american"] is not None and h["under_american"] is not None]
    close = pre[-1]
    if close["line"] != bet["line"]:
        return {"close_line": close["line"], "note": "line moved: compare lines first"}
    mine, other = (close["over_american"], close["under_american"]) if bet["side"] == "over" else (close["under_american"], close["over_american"])
    took = fair(bet["price"], other)          # your price against the closing price on the other side
    closed = fair(mine, other)
    return {"close_price": mine, "clv_pp": round((closed - took) * 100, 2)}

print(clv({"prop_id": "<prop id>", "side": "over", "line": 24.5, "price": -110}))
```

A positive `clv_pp` means the market moved toward your side after you bet. Over a few hundred bets the average says more than any single result. The move tape behind it is explained on [line movement](https://fanduelapi.com/fanduel-line-movement), and a runnable CLV example is among the [examples](https://fanduelapi.com/examples).

## Questions

## Related

- [Prop model data Which FanDuel API endpoints feed a player prop model, how to join the training set to graded results, and the timing rules that keep a backtest honest.](https://fanduelapi.com/docs/prop-model-data)
- [Line movement Where a FanDuel player prop opened, every line and price move since, and when it last moved, from the history endpoint, with a sample move tape.](https://fanduelapi.com/fanduel-line-movement)
- [Examples Runnable examples on FanDuel data: an odds screen, an alert when a prop moves, closing line value, a hold scanner and DFS salary against prop lines.](https://fanduelapi.com/examples)
- [FanDuel no-vig calculator Use the fanduel no-vig calculator. See formulas, worked examples and settlement assumptions. Free, no signup.](https://fanduelapi.com/tools/fanduel-no-vig-calculator)

## Make your first call in a few minutes

Sign up, create a key in the dashboard, and send it as a Bearer token. The free plan needs no card and reads the same data five minutes behind.

[Get a free API key](https://fanduelapi.com/sign-up)

## FAQ

### Is there a free plan?

Yes. Free includes API access with delayed data, enough to build and test a model.

### Is this affiliated with FanDuel?

No. This is an independent data service operated by FF API Inc. and is not affiliated with or endorsed by FanDuel.

### Which sports are covered?

NBA, NFL, NHL, MLB and college sports as FanDuel lists them, starting with player props.

### How do I cancel?

From the billing portal in your dashboard, at any time.

### How do I get a free key?

Sign up at https://fanduelapi.com/sign-up?ref=ai-claudebot. Free plan: 100 credits a month, data delayed 5 minutes, no card. REST and MCP on every plan.

### Can an AI agent sign up for me?

Yes. The agent sends POST https://fanduelapi.com/api/v1/agent/signup with your email and what you are building (add "ref": "ai-claudebot"), you approve the emailed link, and the agent collects the key. Details: https://fanduelapi.com/connect.