MarketMaster API

Query our normalized, cross-platform prediction-market data — live edges and market snapshots across Kalshi, Polymarket, and more — over a fast, read-only REST API. It's the same engine that powers the scanner.

REST · JSON API-key auth CORS-enabled v1

Get your API key →

Introduction

The MarketMaster API gives you programmatic access to our cross-platform engine: edges (markets our model thinks are mispriced, ranked), markets (the latest normalized snapshot across venues), a single-market lookup, cross-platform arbitrage spreads, and the whale trade feed. Every endpoint is a simple GET that returns JSON. There are no SDKs to install — any HTTP client works.

The API is read-only. It never places trades, moves funds, or exposes any individual user's data — only public market data.

Quickstart

Three steps to your first request:

1. Generate a key on your dashboard (Developer API card). Copy it — it's shown only once.
2. Send it in the x-api-key header.
3. Call an endpoint.

curl

curl "https://api.marketmaster.live/v1/edges?limit=5" \
  -H "x-api-key: mmk_live_your_key_here" \
  -H "User-Agent: my-app/1.0"

Authentication

Authenticate every request with your API key in the x-api-key header. Keys look like mmk_live_… and are issued and managed from your dashboard. A key is shown once at creation; store it securely (e.g. an environment variable), never commit it to source control, and rotate it from the dashboard if it's ever exposed.

Treat your key like a password. Requests without a valid key return 401.

Always send a User-Agent header identifying your app. Requests with default library agents (e.g. python-urllib, some curl setups) can be rejected by our edge bot protection. Our official SDKs set one for you.

Conventions

Base URL

https://api.marketmaster.live

Format	All requests and responses are JSON. Responses include `Content-Type: application/json`.
Prices	All prices and fair values are probabilities in the range `0.0`–`1.0` (e.g. `0.43` = 43¢ / a 43% implied chance).
Timestamps	ISO 8601, UTC (e.g. `2026-06-20T21:25:12Z`).
Venues	`kalshi`, `polymarket`, `predictfun`, `manifold`.
CORS	Enabled for all origins, so you can call the API directly from a browser app.
Pagination	List endpoints accept `limit` and `offset` and return `limit`, `offset`, and `has_more` (plus `total` where the full set is counted in-engine). Page by `offset += limit` until `has_more` is `false`.
Caching	Data endpoints send `Cache-Control: public, max-age=30`. Snapshots refresh every few minutes, so a ~30s cache is safe.

Rate limits

Limits are enforced per key across two windows: a per-minute rate and a monthly quota. Pro is included with a MarketMaster Pro subscription.

Tier	Rate	Monthly quota
`free`	60 requests / minute	1,000 requests
`pro`	240 requests / minute	200,000 requests

Headers on every response

`X-RateLimit-Limit-Minute`	Your per-minute ceiling.
`X-RateLimit-Remaining-Minute`	Requests left in the current minute.
`X-RateLimit-Limit-Month`	Your monthly quota.
`X-RateLimit-Remaining-Month`	Requests left this month.

Exceeding the per-minute rate returns 429 rate_limited; exhausting the monthly quota returns 429 quota_exceeded. Both 429 responses include a Retry-After header (seconds to wait). Check /v1/status any time to see your remaining quota.

Edges

GET/v1/edges

The most mispriced markets right now — our model's fair value versus the live price, ranked by the size of the edge. Returns one row per market, deduplicated to the latest reading.

Query parameters

Parameter	Type	Description
`platform`	string	Filter to a single venue: `kalshi`, `polymarket`, `predictfun`, `manifold`.
`category`	string	Filter by category, e.g. `politics`, `sports`, `crypto`.
`limit`	integer	Max rows. Default `50`, max `200`.
`offset`	integer	Rows to skip, for pagination. Default `0`.
`min_edge`	number	Only return edges whose absolute edge is at least this many percentage points.

Response: `edges[]`

Field	Type	Description
`platform`	string	The venue this market trades on.
`market_id`	string	The venue's native market identifier.
`market_title`	string	Human-readable market question.
`market_category`	string	Category, e.g. `politics`.
`outcome`	string	The outcome the edge is on: `YES` or `NO`.
`price`	number	Live market price of that outcome (0–1).
`fair_value`	number	Our model's estimated fair probability (0–1).
`edge_pct`	number	Edge in percentage points — how far price sits from fair value. Larger = more mispriced.
`confidence`	number	Model confidence in the estimate (0–1).
`match_group_id`	integer	ID of the cross-venue match group. Markets sharing this ID are the same real-world event on different venues — useful for spotting arbitrage.
`expires_at`	string	When the market closes (ISO 8601).
`computed_at`	string	When this edge was computed (ISO 8601).

Example

curl

curl "https://api.marketmaster.live/v1/edges?platform=kalshi&limit=2" \
  -H "x-api-key: mmk_live_your_key_here"

JavaScript

const res = await fetch(
  "https://api.marketmaster.live/v1/edges?platform=kalshi&limit=2",
  { headers: { "x-api-key": process.env.MM_API_KEY } }
);
const { edges } = await res.json();

Python

import requests
r = requests.get(
    "https://api.marketmaster.live/v1/edges",
    params={"platform": "kalshi", "limit": 2},
    headers={"x-api-key": MM_API_KEY},
)
edges = r.json()["edges"]

Response

{
  "count": 2,
  "edges": [
    {
      "platform": "kalshi",
      "market_id": "PRES-2028-DEM",
      "market_title": "Will a Democrat win the 2028 election?",
      "market_category": "politics",
      "outcome": "YES",
      "price": 0.43,
      "fair_value": 0.51,
      "edge_pct": 8.0,
      "confidence": 0.62,
      "match_group_id": 1836280,
      "expires_at": "2028-11-07T05:00:00Z",
      "computed_at": "2026-06-20T21:25:12Z"
    }
  ],
  "generated_at": "2026-06-20T21:25:34Z"
}

Markets

GET/v1/markets

The latest snapshot of tracked markets across every venue — title, category, YES/NO price, 24-hour volume, and close time. Sorted by 24h volume (most active first).

Query parameters

Parameter	Type	Description
`source`	string	Filter by venue (alias: `platform`).
`category`	string	Filter by category.
`limit`	integer	Max rows. Default `100`, max `500`.
`offset`	integer	Rows to skip, for pagination. Default `0`.

Response: `markets[]`

Field	Type	Description
`source`	string	The venue.
`source_market_id`	string	The venue's native market id.
`title`	string	Market question.
`category`	string	Category.
`outcome_shape`	string	Market structure, e.g. `binary`.
`yes_price`	number	Current YES price (0–1).
`no_price`	number	Current NO price (0–1).
`volume_24h_usd`	number \| null	24-hour traded volume in USD, when available.
`close_time`	string \| null	When the market closes (ISO 8601).
`last_trade_at`	string \| null	Timestamp of the last trade (ISO 8601).
`fetched_at`	string	When we last snapshotted this market (ISO 8601).

Example

curl

curl "https://api.marketmaster.live/v1/markets?category=politics&limit=50" \
  -H "x-api-key: mmk_live_your_key_here"

Market

GET/v1/market

A single market's latest snapshot plus any live edges we've computed for it. Identify it by source + id.

Query parameters

Parameter	Type	Description
`source`	string · required	Venue: `kalshi`, `polymarket`, `predictfun`, `manifold`.
`id`	string · required	The venue's native market id (`source_market_id`).

Response

Returns market (same shape as a markets[] row) and edges[] (same shape as edges[], most recent first). An unknown id returns 404 not_found.

curl

curl "https://api.marketmaster.live/v1/market?source=kalshi&id=PRES-2028-DEM" \
  -H "x-api-key: mmk_live_your_key_here"

Arbitrage

GET/v1/arbitrage

Cross-platform price spreads for the same outcome on matched markets — the data behind the scanner's compare view. For each match group it reports the cheapest and dearest real-money venue for an outcome and the spread between them, ranked widest first.

Spreads are indicative and gross of fees, slippage, and bid/ask depth — they are not guaranteed arbitrage. Always confirm executable prices on the venue.

Query parameters

Parameter	Type	Description
`min_spread`	number	Only return spreads at least this many percentage points wide.
`limit`	integer	Max rows. Default `50`, max `200`.
`offset`	integer	Rows to skip, for pagination. Default `0`.

Response: `opportunities[]`

Field	Type	Description
`match_group_id`	integer	The cross-venue match group.
`title`	string	Market question.
`outcome`	string	The outcome being compared (`YES`/`NO`).
`spread_pct`	number	Dearest minus cheapest YES price, in percentage points.
`buy_yes`	object	Cheapest venue: `{ platform, market_id, price }`.
`sell_yes`	object	Dearest venue: `{ platform, market_id, price }`.
`computed_at`	string	When these prices were computed (ISO 8601).

The response also carries a top-level disclaimer string restating the gross/indicative caveat.

curl

curl "https://api.marketmaster.live/v1/arbitrage?min_spread=2&limit=10" \
  -H "x-api-key: mmk_live_your_key_here"

Whales

GET/v1/whales

Recent large real-money trades (whale fills) across venues, newest first.

Query parameters

Parameter	Type	Description
`source`	string	Filter by venue.
`min`	integer	Minimum trade size in USD.
`limit`	integer	Max rows. Default `50`, max `200`.
`offset`	integer	Rows to skip, for pagination. Default `0`.

Response: `trades[]`

Field	Type	Description
`source`	string	The venue.
`source_market_id`	string	The venue's native market id.
`trader_name`	string \| null	Public trader handle, when available.
`side`	string	Trade side (e.g. `buy`/`sell`).
`outcome`	string	Outcome traded.
`size_usd`	number	Notional trade size in USD.
`price`	number	Trade price (0–1).
`title`	string	Market question.
`trade_time`	string	When the trade printed (ISO 8601).
`tx_hash`	string \| null	On-chain transaction hash, for on-chain venues.

curl

curl "https://api.marketmaster.live/v1/whales?min=10000&limit=20" \
  -H "x-api-key: mmk_live_your_key_here"

Status

GET/v1/status

Returns your key's tier, limits, and current usage. Useful for monitoring remaining quota.

Response

{
  "ok": true,
  "tier": "free",
  "limits": { "minute": 60, "month": 1000 },
  "usage":  { "minute": 3,  "month": 412 }
}

Errors

Errors return the appropriate HTTP status with a JSON envelope:

{ "error": { "code": "rate_limited", "message": "Per-minute rate limit exceeded. Slow down and retry." } }

Status	Code	Meaning
`401`	`missing_api_key`	No `x-api-key` header was sent.
`401`	`invalid_api_key`	The key is malformed, unknown, or revoked.
`429`	`rate_limited`	Per-minute rate exceeded — back off and retry.
`400`	`invalid_parameter`	A query parameter was invalid (unknown `platform`/`source`, or a missing required `id`).
`404`	`not_found`	No resource matched (e.g. `/v1/market` with an unknown id).
`429`	`quota_exceeded`	Monthly quota exhausted — resets at the start of the month, or upgrade.
`500`	`auth_error`	Temporary problem validating the key — retry shortly.
`502`	`upstream_error`	Transient problem loading data — retry shortly.

Versioning & changes

The API is versioned in the path (/v1/). We may add new fields to responses at any time, so write clients that ignore unknown fields. Breaking changes — removing or renaming fields, changing types — would ship under a new version. This is an early release; endpoints and limits may still evolve.

Disclaimer

Edge and fair-value figures are model estimates provided for informational purposes only. They are not trading advice and not a guarantee of profit. Data is provided as-is, without warranty. You are responsible for complying with the terms and applicable laws of any venue you trade on.

Get your API key →

MarketMaster API

Introduction

Quickstart

Authentication

Conventions

Base URL

Rate limits

Headers on every response

Edges

Query parameters

Response: edges[]

Example

Markets

Query parameters

Response: markets[]

Example

Market

Query parameters

Response

Arbitrage

Query parameters

Response: opportunities[]

Whales

Query parameters

Response: trades[]

Status

Response

Errors

Versioning & changes

Disclaimer

Response: `edges[]`

Response: `markets[]`

Response: `opportunities[]`

Response: `trades[]`