{"id":3651,"date":"2026-08-19T10:00:00","date_gmt":"2026-08-19T10:00:00","guid":{"rendered":"https:\/\/oddspapi.io\/blog\/?p=3651"},"modified":"2026-09-07T14:01:51","modified_gmt":"2026-09-07T14:01:51","slug":"javascript-odds-api-nodejs","status":"publish","type":"post","link":"https:\/\/oddspapi.io\/blog\/javascript-odds-api-nodejs\/","title":{"rendered":"JavaScript Odds API: Resolve Main Lines Correctly in Node.js"},"content":{"rendered":"

Every odds API tutorial on the internet is written in Python. If you build in JavaScript, you get to translate somebody else’s requests<\/code> snippet and hope the nesting survives the trip.<\/p>\n

This guide skips the translation. It is a full Node.js walkthrough of the OddsPapi API: authentication, fixture discovery, the nested odds payload, line shopping, player props, historical prices, and TypeScript definitions derived from a live response. No SDK, no axios<\/code>, no dependencies. Node 18 and later ship fetch<\/code> in the runtime, so the whole tutorial runs on the standard library.<\/p>\n

Every number below comes from one live capture: Los Angeles Dodgers v Kansas City Royals<\/strong>, fixture id1300010963302689<\/code>, pulled at 13:35 UTC on 10 August 2026. That single response carried 18 bookmakers and 6,372 prices<\/strong>.<\/p>\n

Why JavaScript devs hit a wall with odds data<\/h2>\n

Bookmakers do not publish public APIs. DraftKings, Bet365 and Pinnacle all run private endpoints behind rotating tokens and bot detection. The usual JavaScript answer is Puppeteer, and a scraper that renders a sportsbook page in headless Chrome costs you a browser process per book, breaks on every markup change, and gives you one bookmaker at a time.<\/p>\n

OddsPapi collapses that into one HTTP GET. One fixture ID returns every book that prices the game, in one JSON document, with decimal, American and fractional odds already converted.<\/p>\n

\n\n\n\n\n\n\n\n\n\n\n\n
Task<\/th>\nPuppeteer \/ scraping<\/th>\nOddsPapi + native fetch<\/th>\n<\/tr>\n<\/thead>\n
Dependencies<\/td>\nChromium, ~300 MB<\/td>\nNone. Node 18+ built-in fetch<\/code><\/td>\n<\/tr>\n
Books per request<\/td>\n1<\/td>\n18 on the fixture below<\/td>\n<\/tr>\n
Sharp books<\/td>\nBlocked or geo-locked<\/td>\nPinnacle, SBOBet, Circa<\/td>\n<\/tr>\n
Prediction markets<\/td>\nSeparate integration each<\/td>\nKalshi and Polymarket in the same payload<\/td>\n<\/tr>\n
Price formats<\/td>\nParse the DOM string yourself<\/td>\nprice<\/code>, priceAmerican<\/code>, priceFractional<\/code><\/td>\n<\/tr>\n
Historical prices<\/td>\nBuild your own archive<\/td>\n\/historical-odds<\/code>, free tier<\/td>\n<\/tr>\n
Breaks when<\/td>\nThe book ships new CSS<\/td>\nIt does not<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<\/figure>\n

Setup: one file, zero installs<\/h2>\n

Grab a free API key, then create a project. The .mjs<\/code> extension gives you ES modules and top level await<\/code> without a package.json<\/code>.<\/p>\n

node --version    # needs v18 or later\nmkdir odds && cd odds\ntouch lib.mjs<\/code><\/pre>\n
Authentication is a query parameter, not a header. This trips up people who expect Authorization: Bearer<\/code>. Put the key in the URL and every endpoint works the same way.<\/p>\n
\/\/ lib.mjs\nexport const API_KEY = process.env.ODDSPAPI_KEY;\nexport const BASE = \"https:\/\/api.oddspapi.io\/v4\";\nexport const sleep = (ms) => new Promise((r) => setTimeout(r, ms));\n\nexport async function op(path, params = {}, tries = 3) {\n  const url = new URL(`${BASE}\/${path}`);\n  url.searchParams.set(\"apiKey\", API_KEY);          \/\/ query param, NOT a header\n  for (const [k, v] of Object.entries(params)) url.searchParams.set(k, v);\n\n  for (let attempt = 0; attempt < tries; attempt++) {\n    const res = await fetch(url);\n    const body = await res.json();\n\n    if (res.status === 429) {                        \/\/ the API tells you how long to wait\n      const waitMs = body?.error?.retryMs ?? 2000;\n      await sleep(waitMs + 100);\n      continue;\n    }\n    if (!res.ok) throw new Error(`${res.status} ${JSON.stringify(body)}`);\n    return body;\n  }\n  throw new Error(`rate limited on \/${path} after ${tries} tries`);\n}<\/code><\/pre>\n
That retryMs<\/code> field matters more than it looks. Read the rate limit section further down before you write any loop.<\/p>\n
First call: list the sports<\/h3>\n
\/\/ sports.mjs\nimport { op } from \".\/lib.mjs\";\n\nconst sports = await op(\"sports\");\nconsole.log(`${sports.length} sports`);\nconsole.log(sports.slice(0, 5));<\/code><\/pre>\n
$ ODDSPAPI_KEY=your_key node sports.mjs\n69 sports\n[\n  { sportId: 10, slug: 'soccer', sportName: 'Soccer' },\n  { sportId: 11, slug: 'basketball', sportName: 'Basketball' },\n  { sportId: 12, slug: 'tennis', sportName: 'Tennis' },\n  { sportId: 13, slug: 'baseball', sportName: 'Baseball' },\n  { sportId: 14, slug: 'american-football', sportName: 'American Football' }\n]<\/code><\/pre>\n
Step 2: find fixtures (and the date window trap)<\/h2>\n
\/fixtures<\/code> takes a sportId<\/code> and a from<\/code> and to<\/code> date range, up to 10 days apart. The obvious query for today’s games returns almost nothing, and it took a measurement to work out why.<\/p>\n
\/\/ window.mjs\nimport { op, sleep } from \".\/lib.mjs\";\nconst d = (n) => new Date(Date.now() + n * 864e5).toISOString().slice(0, 10);\n\nfor (const to of [d(1), d(2), d(3)]) {\n  const fx = await op(\"fixtures\", { sportId: 13, from: d(0), to });\n  const perDay = {};\n  for (const f of fx) {\n    const day = f.startTime.slice(0, 10);\n    perDay[day] = (perDay[day] ?? 0) + 1;\n  }\n  console.log(`from ${d(0)} to ${to}:`, JSON.stringify(perDay));\n  await sleep(1200);\n}<\/code><\/pre>\n
from 2026-08-10 to 2026-08-11: {\"2026-08-10\":45}\nfrom 2026-08-10 to 2026-08-12: {\"2026-08-10\":45,\"2026-08-11\":107,\"2026-08-12\":2}\nfrom 2026-08-10 to 2026-08-13: {\"2026-08-10\":45,\"2026-08-11\":107,\"2026-08-12\":112,\"2026-08-13\":2}<\/code><\/pre>\n
Look at the last day in each range. It carries 2 fixtures, and both of those start at exactly 00:00:00Z<\/code>. So to<\/code> is a timestamp at midnight UTC of that date, not a whole day. Ask for from=today&to=today<\/code> and you get the 2 games that started at midnight, which is why a same-day query looks like the sport is dead.<\/p>\n
Rule: set to<\/code> to the day after the last day you want.<\/strong><\/p>\n
\/\/ fixtures.mjs\nimport { op } from \".\/lib.mjs\";\nconst day = (n) => new Date(Date.now() + n * 864e5).toISOString().slice(0, 10);\n\nconst fixtures = await op(\"fixtures\", { sportId: 13, from: day(0), to: day(1) });\nconst mlb = fixtures.filter((f) => f.tournamentName === \"MLB\" && f.hasOdds);\n\nfor (const f of mlb) {\n  console.log(f.fixtureId, f.startTime, `${f.participant1Name} v ${f.participant2Name}`);\n}<\/code><\/pre>\n
Two fields do the work here. tournamentName<\/code> filters the league, because sportId: 13<\/code> also returns NPB, KBO, the Mexican League and every minor league affiliate. hasOdds<\/code> tells you whether \/odds<\/code> will return prices at all: skip anything false and you save a request.<\/p>\n
Step 3: the odds payload, and what nobody documents<\/h2>\n
One \/odds<\/code> call on the Dodgers fixture returned 2.36 MB of JSON<\/strong>: 18 bookmakers, 258 distinct markets, 6,372 individual prices. The nesting runs five levels deep.<\/p>\n
bookmakerOdds\n  \u2514\u2500\u2500 \"pinnacle\"\n        \u251c\u2500\u2500 bookmakerIsActive: true\n        \u251c\u2500\u2500 bookmakerFixtureId: \"1633332366\"\n        \u251c\u2500\u2500 fixturePath: \"https:\/\/www.pinnacle.com\/en\/e\/e\/e\/1633332366\"\n        \u251c\u2500\u2500 suspended: false\n        \u2514\u2500\u2500 markets\n              \u2514\u2500\u2500 \"131\"                          \/\/ market id\n                    \u251c\u2500\u2500 bookmakerMarketId: \"...\"\n                    \u251c\u2500\u2500 marketActive: true\n                    \u2514\u2500\u2500 outcomes\n                          \u2514\u2500\u2500 \"131\"              \/\/ outcome id\n                                \u2514\u2500\u2500 players\n                                      \u2514\u2500\u2500 \"0\"    \/\/ the price object\n                                            \u251c\u2500\u2500 price: 1.337\n                                            \u251c\u2500\u2500 priceAmerican: \"-297\"\n                                            \u251c\u2500\u2500 active: true\n                                            \u251c\u2500\u2500 limit: 11127\n                                            \u2514\u2500\u2500 mainLine: true<\/code><\/pre>\n
Three of those book level fields are worth your attention, and none of them appear in a typical tutorial:<\/p>\n