Routeur API

This page says what Routeur is, who it is for, and the three ways to reach it. Read it once, then follow the quickstart. Everything here is read-only: Routeur observes public venue data and never places an order.

What Routeur is

Routeur reads every open market on Kalshi and global Polymarket and proves which contracts imply, exclude or equal each other. A proof uses each venue’s structured contract terms and exact arithmetic; nothing is inferred from a market’s wording, and when the evidence conflicts the relation is withheld rather than guessed. On top of that graph the API serves:

Data	What it is	Where
Events and markets	Every listed market on both venues, grouped into the events people browse, with the best price on each venue	`GET /v1/events`, `GET /v1/markets`
Relations	Proven relations between two markets, on one venue or across venues, with the proof trail behind each one	`GET /v1/markets/{venue}/{id}/relations`, `GET /v1/relations/...`
Prices	Top-of-book asks and bids recorded on every crawl, and quote history	`quote` on every market, `GET /v1/markets/{venue}/{id}/quotes`
Trades	Public fills recorded every minute from both venues	`GET /v1/markets/{venue}/{id}/trades`
Order books	Books recorded live from the venues’ feeds, their history and the feeds’ health	`GET /v1/markets/{venue}/{id}/book`, `/book/history`, `GET /v1/books/health`
Rules	Each market’s rule text, every version of it, the rulebooks above it and the venue’s terms documents	`GET /v1/markets/{venue}/{id}/rules`, `GET /v1/rulebooks/...`
Leads	Two-leg purchases a proven relation says pay at least $1, sized against live order books	`GET /v1/opportunities`
Signals and history	Moves, large fills, one-sided money, unusual flow, calibration and strategies measured against settled markets	`GET /v1/insights/...`, `GET /v1/flow`

Every object that names a market carries its 24-hour volume, its round-trip spread and a liquidity grade, so nothing thin passes for an opportunity. See Liquidity. At the time of writing the latest graph run read 130,310 Kalshi markets and 174,810 Polymarket markets, held 304,955 markets and 131,409 structured propositions, and had proven 1,301 cross-venue equivalences. GET /v1/status reports the current figures.

Who it is for

Traders and desks that want the same question priced on both venues, and to know when a gap is real money after fees and depth.
Researchers who need recorded quotes, trades, books and rule history rather than a venue’s live view.
Builders of monitors and alerts, over the live stream or webhooks.
Agents: every endpoint is also an MCP tool, with the same key and limits.

Three ways in

Way in	Address	Shape	Use it for
REST	`https://api.routeur.app/v1`	34 `GET` endpoints returning JSON	Everything: browsing, history, proofs, books, rules
Live stream	`GET https://api.routeur.app/v1/stream`	Server-Sent Events with topics `quotes`, `trades`, `books`, `relations`, `leads`, `rules`	Following changes as they are recorded, resumable from a cursor
MCP	`POST https://api.routeur.app/mcp`	Streamable HTTP; 38 tools (one per endpoint plus five composed), resources and prompts	Claude, Cursor, ChatGPT and your own agents

One API key opens all three. Send it as X-API-Key: <key> or Authorization: Bearer <key>; see Authentication.

Five things people do first

Browse an event with its outcomes priced on both venues. GET /v1/events?cross_venue=true returns events listed on Kalshi and Polymarket, each outcome with a price per venue and the better one named. See the quickstart.
Find the gap between venues. GET /v1/cross-venue lists every proven cross-venue pair with both quotes; GET /v1/markets/{venue}/{id}/relations?cross_venue=true does it from one market. See Cross-venue pairs.
Check a lead and whether it fills. GET /v1/opportunities returns leads with a depth block sized against the live books: executable says whether at least one pair could be bought for less than it pays. See Leads.
Read a market’s rules and how they changed. GET /v1/markets/{venue}/{id}/rules returns the rule text, every recorded version with a diff, and the rulebooks above it. See Rules.
Follow trades live. GET /v1/stream?topics=trades pushes fills as they are recorded. See Live stream.

Conventions

Convention	Rule
Prices and money	Decimal strings in USD, such as `"0.52"`, never floats. A price is per contract that pays $1, so `"0.52"` is 52 cents.
Times	RFC 3339 in UTC, for example `2026-09-17T12:33:03.021417Z`.
Envelope	Successful responses wrap results in `data`. Graph-derived responses also carry `graph_run`, the hourly run they were read from.
Pagination	`next_cursor` or `next_offset` when more results exist; see Pagination.
Query parameters	Unknown, repeated or out-of-range parameters are rejected with `400 invalid_parameter`, naming the parameter.
Errors	`{"error": {"code": "...", "message": "..."}}`; branch on `code`. See Errors.
Ids	A market is `{venue}/{id}`: a ticker on Kalshi (`KXNFLTOTAL-26SEP17DETBUF-55`), a slug on Polymarket (`nfl-det-buf-2026-09-18-total-54pt5`).

Status of the service

The API is in private preview. Keys are issued by the Routeur team. Responses are observations of public venue data, not quotes or investment advice; see Data and limits.

Get started

Concepts

Agents & MCP

Webhooks

Reference

What Routeur is

Who it is for

Three ways in

Five things people do first

Conventions

Status of the service

What Routeur is

Who it is for

Three ways in

Five things people do first

Conventions

Status of the service

Related