Polymarket US odds API

Polymarket US odds API for real-time Polymarket US prices converted to American, decimal or probability odds and set next to every sportsbook on one event id.

Polymarket US is the US-facing exchange under the Polymarket name: a CFTC-regulated venue, separate from Polymarket's international platform, where users trade event contracts that pay $1 if an outcome happens. For sports data, that makes it a prediction market priced by US traders, quoted in cents, and sitting alongside regulated sportsbooks. Developers building odds screens, line-shopping tools and models want its prices in the same form as the sportsbooks so the comparison is direct. This page covers what PreciseAPI's Polymarket US odds API returns, how it differs from the international polymarket source, and how to use its prices in cross-venue comparisons without overlooking fees and size.

#Does Polymarket US have a public API?

Polymarket US publishes developer documentation of its own. There's a public gateway for reading markets and events without a key, and an authenticated API for trading that requires a verified account. If you're trading on Polymarket US, that's the interface to use. It's also a good choice if your product only ever shows Polymarket US. Once you need it next to a dozen sportsbooks and other exchanges, the work shifts from fetching prices to matching them, and that's where a normalized feed earns its keep.

What you won't get from it is a Polymarket US odds API in the sportsbook sense. Markets are organized around Polymarket US's own identifiers, prices are contract prices, and nothing connects a Polymarket US market to the same game at FanDuel or Pinnacle. PreciseAPI collects Polymarket US's sports prices and normalizes them into the schema we use for every source: shared event ids and outcome ids, standard market keys, and American, decimal or probability formats. PreciseAPI is an independent provider. We have no partnership with Polymarket, and this isn't an official Polymarket US feed.

#How Polymarket US differs from Polymarket

Both venues use the Polymarket brand, but they're separate exchanges with separate order books and separate users:

Since the books are separate, the same game can show different prices on each. Don't merge them into one "Polymarket" column. Our international Polymarket page covers the other venue.

#What Polymarket US data is included

Polymarket US is a type: "exchange" source. The Polymarket US odds feed carries full-game game-winner markets under the moneyline key, including the draw in soccer. Each outcome includes:

• price: in the format you request with format
• liquidity: the size available at that price, in USD
• id: the selection id, the same id the outcome has at every other source

Spreads, totals and player props aren't part of the Polymarket US feed today. For those, use the sportsbooks and the other exchanges.

Conversion follows the usual contract math. A contract at 46 cents is a 46% implied probability, decimal odds of 2.174 (1 / 0.46), and American odds of +117. See /docs/formats for how PreciseAPI rounds each format.

#Polymarket US odds by league

The coverage endpoint lists Polymarket US lines for 14 leagues:

• NFL: the most active contracts, and the most useful comparison against regulated sportsbooks.
• NCAAF: wide slates with depth focused on the biggest games.
• NBA: winner contracts that move fast on injury news.
• WNBA: thinner markets, so check size before comparing.
• NCAAB: many games on busy nights, with uneven depth.
• MLB: daily winner markets that follow pitching news.
• NHL: winner markets where price gaps between venues are often small.
• Soccer: three-way markets. A "no" on one side includes the draw.
• Tennis: match winners with big in-play swings.
• UFC: fight winners through fight week.
• League of Legends, CS2, Valorant and Dota 2: esports match winners, where few US-facing venues post prices at all.

#Polymarket US next to sportsbooks

A sportsbook sets a line with a margin built in. A prediction market's price is set by traders. The two often disagree, and a cross-venue odds screen shows where. Comparing them fairly takes three checks: convert both to the same format, account for the exchange's trading fees, and read the price together with the size available at it.

#Worked example: comparing a contract price with a sportsbook line

An NFL game shows:

Step by step:

1. Best price per outcome. The away side is cheaper on Polymarket US (46.00% versus 48.78%). The home side is cheaper at the sportsbook (55.56% versus 56.00%).

2. Each venue's margin. The sportsbook's prices add to 104.34%, a hold of about 4.2%. Polymarket US's two contracts add to 102.00%, which reflects the gap between buying each side rather than a margin set by a trading team.

3. Fees. Purely for illustration, if fees raise the effective contract price by half a cent to $0.465, the away price becomes about +115; at a full cent ($0.47), about +113. Both are still ahead of the sportsbook's +105 in this example, but a smaller gap could disappear. Polymarket US publishes its own fee terms, so use those, not these placeholder figures.

4. Size. The liquidity field tells you how much is available at the quoted price. A price with very little behind it is a weaker signal than the same price in a deep market.

The odds formats guide handles the format conversions, and the prediction market and implied probability glossary entries cover the terms.

Soccer adds a twist. A winner market has three outcomes: home, draw and away. A "no" contract on one team includes the draw, so it isn't the same outcome as a sportsbook's two-way price on the other team. Compare like with like: one entry per outcome, three outcomes per market. The best lines endpoint handles this for you, listing the best price per outcome (best_price), the venues offering it (best_books) and how many sources are quoting the market (books_quoting), for two-way and three-way markets alike.

#Why Polymarket US belongs on an odds screen at all

Polymarket US odds data adds something a sportsbook-only screen lacks. A sportsbook's price is a decision by its trading team plus a margin. A prediction market's price is where buyers and sellers actually met. When the two agree, that's reassuring. When they don't, one of them is probably slow, and the updated_at timestamps usually tell you which. For line shopping, Polymarket US is one more venue your screen can compare on a game winner. For models, it's an independent estimate you can test against the sharp books over a season. In both cases, read the price with its liquidity: a deep market says a lot more than a thin one.

#How to use the Polymarket US odds API

The source id is polymarket_us. Pull NFL winner markets from Polymarket US alongside two sportsbooks:

curl -s "https://api.preciseapi.com/v1/odds?league=nfl&books=polymarket_us,fanduel,draftkings&markets=moneyline&format=decimal" \
  -H "Authorization: Bearer $PRECISEAPI_KEY"

Or ask for the best available price per outcome across Polymarket US and the sportsbooks your app tracks:

curl -s "https://api.preciseapi.com/v1/best-lines?league=nfl&markets=moneyline&books=polymarket_us,fanduel,draftkings,betmgm,caesars" \
  -H "Authorization: Bearer $PRECISEAPI_KEY"

Each event lists its markets, with the best price for every outcome and the venues offering it:

{
  "id": "evt_0kq3w8rn1zd",
  "league": "nfl",
  "status": "scheduled",
  "markets": [
    {
      "key": "moneyline",
      "period": "full_game",
      "books_quoting": 5,
      "outcomes": [
        { "id": "sel_1xq7b0ne4lv", "name": "Chicago Bears", "side": "away", "best_price": 110, "best_books": ["polymarket_us"] },
        { "id": "sel_0hd5r9wk2mp", "name": "Minnesota Vikings", "side": "home", "best_price": -105, "best_books": ["draftkings"] }
      ]
    }
  ]
}

Best prices are quoted prices before exchange fees, so have your app apply Polymarket US's fee terms and check liquidity from /v1/odds before displaying a contract price as the best one. /v1/odds costs 2 credits per call and /v1/best-lines costs 3. WebSocket streaming comes with Syndicate, not with the REST-only Edge and Sharp plans, and lets your app update Polymarket US live odds as deltas arrive instead of polling (/docs/streaming). If Polymarket US stops reporting a market, we mark it suspended. Suspended markets are always left out of best-line results, and out of odds responses unless you pass include_suspended=true, so a stale contract price can't show up as the best one.

#Why not scrape Polymarket US?

Polymarket US offers its own interfaces, so the real question is whether to build and maintain your own cross-venue pipeline:

• You'd have to match every Polymarket US market to the right game and outcome at each sportsbook, and keep that mapping working as new markets are listed.
• Contract prices have to be converted and lined up with sportsbook formats.
• Connections, rate limits and upstream changes need constant attention.
• You need your own stale-price detection, or your screen will show prices that no longer exist.
• Automating the website instead of using official interfaces can breach the operator's terms. Respect Polymarket US's terms.

PreciseAPI does this work for every source, which makes it a practical base for an odds screen that includes prediction markets. The prediction markets API page covers the other exchanges in the feed.

Polymarket and Polymarket US are trademarks of their owner, used here for identification only. PreciseAPI is not affiliated with or endorsed by Polymarket. Availability of Polymarket US varies by jurisdiction.

#Frequently asked questions

#Does Polymarket US have an API?

The Polymarket US API covers market data and trading on its own exchange. It doesn't provide sports odds mapped to sportsbook events. PreciseAPI's Polymarket US odds API collects those prices and normalizes them alongside the sportsbooks and exchanges we cover.

#Is Polymarket US the same as Polymarket?

No. They're separate venues with separate order books. PreciseAPI tracks them as two sources, polymarket_us and polymarket, so you can compare their prices.

#Which Polymarket US markets are in the feed?

Game-winner markets across 14 leagues, including NFL, NBA, MLB, NHL, soccer, tennis, UFC and four esports titles.

#How fast do Polymarket US odds update?

PreciseAPI refreshes in-play prices in under 500 ms and pre-match prices every 1–2 seconds. The Syndicate plan adds in-play odds and can stream changes over WebSocket.

#Do Polymarket US prices include fees?

No. Prices are the quoted contract prices, converted to the format you request. Apply Polymarket US's published fee terms in your app, and check each outcome's liquidity before comparing it with a sportsbook price.

#Is there a free trial?

Yes. The Sandbox plan is free, with 50 credits for the Sandbox chat in your dashboard, where you can ask about Polymarket US prices in plain English, and no card required. API access starts on Edge. See the pricing page for paid plans.