API reference

Closing line value

How far a price you took beat the book's close and the fair close, for one selection.

GET/odds/v1/clv

Cost: 1 token
Authentication: X-API-Key, your own key (not the demo key)

Parameters

event_idstringrequired
An event_id from /events, sent back verbatim.
selection_keystringrequired
The selection_key from /odds (live or finished) or /history.
bookstringrequired
The book you bet at, a key from /books.
oddsstringrequired
The price you took, in format.
formatstringoptional
decimal (1.55), american (-182, 150; send + as %2B) or fractional (11/20). Prices in the response use the same format.Default: decimal

Formula

Prices are decimal with the stake included. This is the standard price-ratio CLV: positive means you beat the close. Percentages are 2 dp and computed in decimal whatever format you send.

clv_pct          = (taken / close_odds - 1) * 100
clv_vs_fair_pct  = (taken / fair_odds  - 1) * 100

It equals the ratio of implied probabilities, p_close / p_taken - 1 with p = 1 / odds, not the difference between them. Against fair_odds it is your expected return per unit staked if the fair close is the true probability.

Request

curl -s "https://api.b337.ai/odds/v1/clv?event_id=baseball%2Fus%2Fmlb%2Fphiladelphia_phillies_v_tampa_bay_rays%2F2026-09-26&selection_key=4ec43f065e08&book=betfair&odds=1.95" \
  -H "X-API-Key: $ODDS_API_KEY"

import os
import requests

resp = requests.get(
    "https://api.b337.ai/odds/v1/clv",
    params={"event_id": "baseball/us/mlb/philadelphia_phillies_v_tampa_bay_rays/2026-09-26", "selection_key": "4ec43f065e08", "book": "betfair", "odds": "1.95"},
    headers={"X-API-Key": os.environ["ODDS_API_KEY"]},
    timeout=10,
)
resp.raise_for_status()
print(resp.json())

// Node 18+, saved as an .mjs file
const res = await fetch("https://api.b337.ai/odds/v1/clv?event_id=baseball%2Fus%2Fmlb%2Fphiladelphia_phillies_v_tampa_bay_rays%2F2026-09-26&selection_key=4ec43f065e08&book=betfair&odds=1.95", {
  headers: { "X-API-Key": process.env.ODDS_API_KEY },
});
console.log(await res.json());

Response

200 OK

{
  "schema_version": 1,
  "event_id": "baseball/us/mlb/philadelphia_phillies_v_tampa_bay_rays/2026-09-26",
  "selection_key": "4ec43f065e08", "book": "betfair", "status": "finished",
  "market": "head_to_head", "name": "Philadelphia Phillies",
  "label": "Philadelphia Phillies", "player": null, "line": null,
  "direction": null, "period": null,
  "taken_odds": 1.95, "off_at": "2026-09-26T23:15:00Z",
  "close_odds": 1.86, "closed_at": "2026-09-26T23:11:58Z", "lag_seconds": 182,
  "clv_pct": 4.84, "close_reason": null,
  "fair_odds": null, "fair_method": null, "fair_anchor": null,
  "clv_vs_fair_pct": null, "fair_reason": "no_fair_price",
  "odds_format": "decimal", "generated_at": "2026-10-05T03:39:45Z"
}

Here the betfair close was 1.86 and the price taken 1.95, so clv_pct is 4.84. No fair close exists for this market, so the fair side is null with a reason.

Null and reason codes

When a side cannot be computed its fields are null and close_reason or fair_reason says why. A null is never a zero.

Reason	Meaning
`event_not_started`	The event has not gone off; no close exists yet.
`close_pending`	In play and the close has not been recorded yet. Retry later.
`no_close_captured`	The event is over and we stored no close for it.
`selection_not_found`	No closed selection has that key: a wrong key, or the market was not captured at the close.
`book_not_closed`	The selection closed, but not at that book. books_closed lists the books that did.
`no_fair_price`	No fair close: pinnacle did not price a complete two or three way set, or it is a handicap.
`unknown_event`	Batch rows only: no such event_id. A single GET answers 404.

Fields

close_odds is that book's closing price for the selection; closed_at and lag_seconds say when and how long before the off. See opening and closing prices.
fair_odds is the margin-free close, with fair_method and fair_anchor naming how it was derived.
selection_key is the same key as /odds and /history. Prices in the response use your format.
The demo key cannot call this (403 plan_required). For many bets at once use POST /clv.