Favourites

Parameters

Name	In	Type	Required	Description
course_id	path	string	yes	Opaque course identifier.
run_type	query	string	no	Restrict to one run type.
field_size	query	string	no	A field size band. Favourite performance depends heavily on how many it is beating.

Request

curl https://api.apihorseracing.com/v1/courses/cr_JSRC8Z/favourites \
  -H "X-API-Key: $AHR_KEY"

$ch = curl_init('https://api.apihorseracing.com/v1/courses/cr_JSRC8Z/favourites');
curl_setopt_array($ch, [
    CURLOPT_RETURNTRANSFER => true,
    CURLOPT_HTTPHEADER     => ['X-API-Key: ' . getenv('AHR_KEY')],
]);
$data = json_decode(curl_exec($ch), true)['data'];

const res = await fetch(
  'https://api.apihorseracing.com/v1/courses/cr_JSRC8Z/favourites',
  { headers: { 'X-API-Key': process.env.AHR_KEY } }
);
const { meta, data } = await res.json();

import os, requests

r = requests.get(
    "https://api.apihorseracing.com/v1/courses/cr_JSRC8Z/favourites",
    headers={"X-API-Key": os.environ["AHR_KEY"]},
).json()

Response

200 OK application/json harvested 8 days ago

{
    "meta": {
        "request_id": "7b86fe7f06ace2a5",
        "data_as_of": "2026-09-12T05:10:27+00:00",
        "plan": "analyst",
        "window": "2017 → upcoming",
        "count": 3
    },
    "data": {
        "course_id": "cr_JSRC8Z",
        "course": "Fontwell",
        "window": {
            "from": null,
            "to": null,
            "note": "The whole archive. Your plan sets no date limit."
        },
        "note": "Favourites only, joint favourites included.",
        "overall": {
            "runs": 1395,
            "priced": 1395,
            "first": 503,
            "second": 294,
            "third": 204,
            "fourth": 88,
            "win_pct": 0.3606,
            "top3_pct": 0.7176,
            "expected_wins": 468.49,
            "a_e": 1.074,
            "a_e_range": [
                0.98,
                1.167
            ],
            "a_e_beats_market": false,
            "significant": false,
            "low_sample": false,
            "pl_1pt": -200.01,
            "roi_pct": -14.34
        },
        "by": "run_type",
        "run_type": [
            {
                "run_type": "Hurdle",
                "runs": 217,
                "priced": 217,
                "first": 67,
                "second": 53,
                "third": 25,
                "fourth": 14,
                "win_pct": 0.3088,
                "top3_pct": 0.6682,
                "expected_wins": 68.26,
                "a_e": 0.982,
                "a_e_range": [
                    0.747,
                    1.217
                ],
                "a_e_beats_market": false,
                "significant": false,
                "low_sample": false,
                "pl_1pt": -53.08,
                "roi_pct": -24.46
            },
            {
                "run_type": "Chase",
                "runs": 173,
                "priced": 173,
                "first": 67,
                "second": 34,
                "third": 24,
                "fourth": 13,
                "win_pct": 0.3873,
                "top3_pct": 0.7225,
                "expected_wins": 60.47,
                "a_e": 1.108,
                "a_e_range": [
                    0.843,
                    1.373
                ],
                "a_e_beats_market": false,
                "significant": false,
                "low_sample": false,
                "pl_1pt": -18.67,
                "roi_pct": -10.79
            },
            "… 1 more"
        ]
    }
}

A real response from /v1/courses/cr_JSRC8Z/favourites, captured by calling the live API rather than written by hand.

Response fields

Each field is described once and rendered on every endpoint that returns it, so the wording cannot drift between pages.

Field	Type	What it is
course_id	string	Opaque course identifier.
course	string	Course name.
window	string	How far back and forward that plan can read.
runs	integer	Rides in the slice, priced or not.
priced	integer	Rides carrying a starting price. A/E and the profit figures use these; runs is the wider count.
first	integer	Wins.
second	integer	Seconds. Positions are returned separately so you apply your own place terms.
third	integer	Thirds.
fourth	integer	Fourths.
win_pct	number	Wins over runs. The number everyone quotes and the one that tells you least.
top3_pct	number	First, second or third over runs. Not a place strike rate; place terms vary.
expected_wins	number	Wins the market implied, summed over the slice.
a_e	number	Actual wins over expected. Above 1.00 means winning more often than the prices said.
a_e_range	array	Ninety five percent interval on A/E. If it spans 1.00 the figure is not evidence of anything.
a_e_beats_market	boolean	True only where the whole interval sits above 1.00.
significant	boolean	Whether the interval excludes 1.00 in either direction.
low_sample	boolean	Fewer than five expected wins. Treat A/E as noise.
pl_1pt	number	One point on every runner, settled at starting price.
roi_pct	number	Level stakes return. Backing everything loses more than the book margin, because equal stakes overweight the longshots.
run_type	string	Flat, Hurdle, Chase or NH Flat.

What varies by jurisdiction

Run type is filled in behind the results crawl

The code a race was run under lives on the horse profile rather than the race, so it arrives on a later pass. A null run_type means not yet fetched, not unclassified.

Errors this endpoint returns

Code	Status	When
unauthorized	401	No key, or one we do not recognise. Check the header name and that the key has not been rotated from your account page.
upgrade_required	403	The endpoint returns computed statistics and your plan does not include them. The body names every plan that does reach it, so you never have to look it up.
not_found	404	The identifier is well formed but nothing has it. Distinct from invalid_id, which means the identifier itself is wrong.
invalid_id	422	The prefix does not match the kind of thing the path expects, or the identifier is malformed. A horse id passed where a race is wanted lands here rather than returning the wrong race.
invalid_param	422	A date that is not YYYY-MM-DD, a by= dimension we do not have, or a cursor that did not come from us. The message names the parameter.
rate_limited	429	Past your per-minute rate. Retry-After is set, and X-RateLimit-Remaining tells you where you stand on every successful response too.
server_error	500	Ours, not yours. Every response carries a request_id; quote it and we can find the exact request.

Run it live

A real request from your browser straight to api.apihorseracing.com with your own key. Nothing is proxied and nothing is logged by this page.

Your API key

Remembered in this browser so you do not paste it on every page.

course_id

run_type optional

field_size optional

What this is for

How the market leader holds up at this track: strike rate, place rate, A/E and level stakes, split by field size.

The favourite is the single most useful baseline in racing, because it is the market's own best guess and every model should be measured against it rather against random selection.

Across the whole archive favourites return an A/E close to 1.00 and lose money at a rate near the book margin, which is what an efficient market looks like. A course and field size where that is not true is worth a second look, though most apparent exceptions are sample size.

Joint favourites are all counted as favourites, since they share the shortest price. This inflates the runner count slightly in the races where it happens and is the honest treatment: picking one arbitrarily would be worse.

Common uses

Setting a benchmark

Before claiming a method works, check what simply backing the favourite here would have returned.

Finding a track where the market struggles

A low favourite A/E with a tight interval means something at this course is harder to price than usual.

Sizing an upset

Field size changes everything. A favourite in a field of five and one in a field of twenty are different propositions.

Available on