# River Markets

**Canonical:** https://apis.io/providers/river-markets/  
**Website:** https://docs.rivermarkets.com  
**APIs profiled:** 13

River Markets is a unified prime brokerage for prediction markets, consolidating multiple exchanges — Kalshi, Polymarket, and Polymarket US (with Novig and Rothera planned) — behind a single account, order-management system, and REST + WebSocket API. Every contract across all venues is assigned a unified River ID, so professional and institutional traders can search markets, place and route orders (including icebergs, pegs, stop-losses, and take-profits with smart order routing), track positions and P&L across isolated subaccounts, and stream live fills, orderbooks, orders, and trade prints from one integration. Requests are Ed25519-signed so the private key never leaves the client process. Founded by ex-BlackRock and high-frequency trading quants and backed by Y Combinator (Spring 2026).

## Kin Score — 39.3 / 100 (developing)

Scored 2026-08-20 under rubric 0.12.0. Trend: flat (+0.0 from 39.3).

| Facet | Score |
|---|---|
| Discoverability | 81.5 |
| Contract Quality | 72.2 |
| Governance | 16.7 |
| Contract Governance | 16.7 |
| Operational Transparency | 2.6 |
| Developer Ergonomics | 58.9 |
| Commercial Clarity | 0.0 |
| Access Clarity | 0.0 |

Regulatory layer — **Securities & Market Data**: 28.3 (matched via tags).

## Agent readiness — 37.3 (agent-ready)

| Dimension | Value |
|---|---|
| Spec Presence | yes |
| Agentic Access | derived |
| Reversibility Documented | documented |
| MCP Server | no |
| Auth Clarity | yes |
| Idempotency | no |
| Error Semantics | verified |
| OpenAPI Examples | no |
| Rate Limit Signal | no |
| Event Surface Described | derived |
| Agent Skills | derived |
| Well Known Catalog | no |
| Consent Identity | no |
| Agent Card | no |
| Dry Run Mode | no |

## Access

Self-serve signup — onboarding: self-serve, pricing: unknown, trial: no (confidence: medium).

## APIs (13)

- **River Markets balance API** — The balance API from River Markets — 1 operation(s) for balance.
- **River Markets complex-orders API** — Manage complex orders: conditional orders (take-profit and stop-loss), TWAP, and other advanced order types.
- **River Markets fair-values API** — The fair-values API from River Markets — 2 operation(s) for fair-values.
- **River Markets fills API** — Retrieve trade execution history and fill details.
- **River Markets generic-assets API** — The generic-assets API from River Markets — 3 operation(s) for generic-assets.
- **River Markets markets API** — Search and discover prediction markets across Kalshi and Polymarket.
- **River Markets orderbooks API** — The orderbooks API from River Markets — 2 operation(s) for orderbooks.
- **River Markets orders API** — Place and manage orders on prediction market exchanges.
- **River Markets positions API** — View current portfolio positions across all connected exchanges.
- **River Markets prices API** — Get historical price data and candlesticks from exchanges.
- **River Markets subaccounts API** — Manage trading subaccounts. Each subaccount can have its own exchange credentials and positions.
- **River Markets tradeprints API** — Recent trades for a market. Pairs with the /v1/ws/tradeprints WebSocket for live updates.
- **River Markets watchlists API** — The watchlists API from River Markets — 4 operation(s) for watchlists.

## MCP servers (1)

- **River Markets MCP Server**

## Agentic access (1)

- **River Markets Agentic Access** — 48 operations · 24 acting

## Security (2)

- **River Markets Authentication** — apiKey/http · 4 schemes
- **River Markets Domain Security** — TLSv1.3 · DMARC

## Tags

Company, Prediction Markets, Trading, Prime Brokerage, Financial-Services, Order Management, Market Data, WebSocket, Fintech

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Profiled by [API Evangelist](https://apievangelist.com) and published on [APIs.io](https://apis.io/providers/river-markets/). Scores are computed from the provider's own public artifacts under a published rubric.