Polymarket

Prediction Markets

Production-grade Polymarket data — markets, prices, activity, and P&L — through a single HTTP API

Power AI trading backtests, copy-trading apps, and portfolio dashboards with on-chain Polygon data enriched with Polymarket metadata. Part of the Token API.

✓Read-only REST endpoints covering markets, OHLCV, open interest, activity, positions, and platform aggregates
✓On-chain event data from Polygon, enriched with Polymarket scraper metadata
✓Scales from one-off research scripts to always-on trading agents

Get API access 📊 See more Stats! →

Polymarket Website →

What you get with the Prediction Markets API

REST endpoints

Markets, OHLCV, OI, activity, positions, platform, users

Polygon on-chain

Trades, splits, merges, redemptions — at the tx level

Per-user P&L

Realized and unrealized PNL, cost basis, current price

Hourly refresh

Aggregated leaderboards updated continuously

// 01 · Headline metrics

24-hour macro

Six complete 4-hour buckets as of 2026-05-24.
Queried live via /v1/polymarket/platform.

Net open interest · peak bucket↘ -49.2% over window

$55.18M

Outcome-share liquidity locked at 2026-05-23 00:00 UTC — the highest of the window. Bucket average $31.99M · 24h OI flow $191.97M.

Buy vs. sell volume · 24h

2.82×Sell-side dominated every bucket. $89.00M sold vs $31.60M bought across $120.61M of total notional.

26.2%BUY

SELL73.8%

Buy volume$31.60M

Sell volume$89.00M

Total fees0.86%

$1.04M

Vol-weighted rate.

Total trades↗ 100.0k/hr

2.40M

447.3k buys · 1.95M sells.

Avg trade size6 buckets

$50.23

Volume / trades. Sell-weighted.

OI transactionssplit/merge

2.22M

2.00M splits · 221.7k merges.

// 03 / Daily BTC market

BTC Direction Market vs Spot Price

Polymarket Up probability against Hyperliquid BTC OHLCV over the active Polymarket trading window.
Cached live requests via /v1/polymarket/markets/ohlc and /v1/hyperliquid/markets/ohlc.

OHLCV 10m intervals

Bitcoin Up or Down on May 4?

bitcoin-up-or-down-on-may-4-2026 / 2026-05-03 16:00 to 2026-05-04 16:00 UTC / $202.1k Polymarket volume / 3,394 trades. Peak bucket $15.7k at 2026-05-04 15:30 UTC.

Up 100%Down 0%BTC $79,984

token_id 481527055417...79417776peak 2026-05-04 15:30 / $15.7kBTC range $78,293 to $80,475

// 02 · All-time leaders

Largest Volume

Highest-volume Polymarket markets to date, sorted by lifetime notional.
Queried live via /v1/polymarket/markets.

Polymarket Website →

01
Will Donald Trump win the 2024 US Presidential Election?
Jan 4, 2024 → Nov 5, 2024·Resolved·YesNo
$1.53B
Lifetime vol
02
Will Kamala Harris win the 2024 US Presidential Election?
Jan 4, 2024 → Nov 4, 2024·Resolved·YesNo
$1.04B
Lifetime vol
03
Will Donald Trump be inaugurated?
Nov 1, 2024 → Jan 20, 2025·Resolved·YesNo
$400.4M
Lifetime vol
04
Will the Sacramento Kings win the 2025 NBA Finals?
Sep 24, 2024 → Jun 23, 2025·Resolved·YesNo
$378.0M
Lifetime vol
05
Will Nicolae Ciucă win the 2024 Romanian Presidential election?
Nov 8, 2024 → Dec 8, 2024·Resolved·YesNo
$326.5M
Lifetime vol
06
US forces enter Iran by April 30?
Mar 18, 2026 → Apr 30, 2026·Resolved·YesNo
$269.0M
Lifetime vol
07
Will Zelenskyy wear a suit before July?
May 22, 2025 → Jun 30, 2025·Resolved·YesNo
$242.2M
Lifetime vol
08
Will any other Republican Politician win the 2024 US Presidential Election?
Jan 6, 2024 → Nov 5, 2024·Resolved·YesNo
$241.7M
Lifetime vol

// 04 · Flow over time

Volume, bucketed

Each bar is a complete 4-hour window. Peak activity at 2026-05-23 16:00 UTC.
Queried live via /v1/polymarket/platform.

Traded volume · stacked buy / sell

$120.61M / 24h

Sum of buy + sell volume across the 6 complete buckets. Peak bucket $26.07M (2026-05-23 16:00). Bucket average $20.10M.

BuySell

avg bucket $20.10Mpeak 2026-05-23 16:00 · $26.07Mlow 2026-05-23 04:00 · $14.87M

// 05 · Raw buckets

Hourly breakdown

Exact response, newest first. Partial current bucket excluded from totals.
Queried live via /v1/polymarket/platform.

Bucket (UTC)	Volume	Buy	Sell	Trades	Net OI	Fees	Rate
2026-05-23 20:00	$21,826,992	$6,066,576	$15,760,417	441,133	$28,015,196	$175,312	0.80%
2026-05-23 16:00	$26,069,559	$5,863,463	$20,206,096	446,310	$30,477,288	$241,183	0.93%
2026-05-23 12:00	$21,182,697	$6,148,816	$15,033,881	409,690	$21,901,332	$176,623	0.83%
2026-05-23 08:00	$17,653,215	$5,331,946	$12,321,268	378,338	$22,779,654	$145,012	0.82%
2026-05-23 04:00	$14,874,400	$3,755,350	$11,119,050	349,376	$33,616,077	$123,313	0.83%
2026-05-23 00:00	$18,999,072	$4,435,705	$14,563,367	376,314	$55,176,967	$175,529	0.92%

6 rows · complete buckets only · usdc 6dp normalizedquery 357 ms · refreshes ≤ 60s

How teams use it

Three patterns we see most often. Each uses a small subset of the endpoints — you can mix them as needed.

AI Trading Backtesting

Replay historical price action per outcome token and stress-test strategies against real liquidity events. Combine OHLCV with the activity feed to reconstruct fills and fees bar-by-bar.

Sample response

[
  {
    "timestamp": "2026-04-01 00:00:00",
    "open": 0.997,
    "high": 0.998,
    "low": 0.997,
    "close": 0.998,
    "volume": 295143.37,
    "trades": 1206,
    "buys": 498,
    "sells": 708,
    "unique_makers": 592,
    "unique_takers": 121,
    "total_fees": 0,
    "fee_count": 0,
    "effective_fee_rate": 0,
    "market": {
      "condition_id": "0x6331a779482df72d904c3c1e12b6409ff836bc06f8c97945cba9b25ada2c605c",
      "market_slug": "will-the-portland-trail-blazers-win-the-2026-nba-finals",
      "token_id": "48262548906086150698299934962091284390063927164151224719187427455086357699251",
      "outcome_label": "No",
      "closed": false
    }
  }
]

Copy Trading

Watch the top traders from the user leaderboard and mirror their entries and exits. The activity feed emits every trade, split, merge, and redemption with block-level timing so you can react in near real-time.

Sample response

[
  {
    "event_type": "trade",
    "timestamp": "2026-04-02 16:51:31",
    "block_num": 85014327,
    "tx_hash": "0xf190865afd395e2f4b8f2e5f8ceb2c05a86d94a73ea411e8a8a3fc649924c420",
    "user": "0x38e598961dd0456a7fb2e758bd433d3e59fb8a4a",
    "amount": "3976744",
    "value": 3.98,
    "fee_amount": "526315",
    "fee_value": 0.53,
    "market": {
      "condition_id": "0xcb37916b953e6b37a5be32ceabc5a093614be15d9e6abb7668bf6400fbf36d46",
      "market_slug": "bitcoin-up-or-down-on-april-3-2026",
      "token_id": "3861173442961229042274748637211736540847931193208187121747580704941582603312",
      "outcome_label": "Down",
      "closed": false
    }
  }
]

User Portfolio P&L

Build wallet dashboards and tax exports that show what a user holds across every Polymarket outcome token — with cost basis, current price, and realized vs unrealized PNL.

Sample response

[
  {
    "user": "0x38e598961dd0456a7fb2e758bd433d3e59fb8a4a",
    "buy_cost": 6438.35,
    "sell_revenue": 247.09,
    "realized_pnl": -6191.26,
    "unrealized_pnl": 9005.64,
    "total_pnl": 2814.38,
    "pnl_pct": -0.96,
    "net_position": 9096.61,
    "avg_price": 0.68,
    "current_price": 0.99,
    "position_value": 9005.64,
    "active": true,
    "buys": 693,
    "sells": 20,
    "transactions": 713,
    "market": {
      "condition_id": "0x59feadddd58e7821c086ee9f3dc4f544514b94ebd0e8d645a3c4d80ebdd354a2",
      "market_slug": "btc-updown-5m-1771359600",
      "token_id": "25362470215305294361999917933416973453076214567033270695579745712197481070383",
      "outcome_label": "Up",
      "closed": false
    }
  }
]