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PMXT: what it does, what it costs, where it stops
Last checked 2026-09-08
PMXT is an open-source unified API for prediction markets, modeled on CCXT. One method name, one response shape, 15 venues including Polymarket, Polymarket US, Kalshi, Limitless and Smarkets. The repo has 2,138 GitHub stars and ships Python (pip install pmxt) and TypeScript (npm install pmxtjs) SDKs at version 2.54.0.
It is built for developers who want cross-venue market data or bots in a single codebase. Traders who only need one venue are better served by that venue's official SDK.
What it does
The SDK exposes the same calls on every venue class: fetch_markets, fetch_events, fetch_order_book, fetch_ohlcv, fetch_trades, create_order, cancel_order, fetch_balance and fetch_positions. Support varies by venue; the docs say catalog reads work on every ingested venue, live reads where the venue exposes the data, and writes where the venue has a trading API.
The Router layer adds cross-venue search over a hosted catalog, matched market clusters with relation types and confidence scores, and price comparison across venues. The catalog currently ingests Polymarket, Kalshi, Opinion, Limitless, Smarkets, Probable and Myriad.
It runs two ways. Hosted mode uses a PMXT API key and PMXT's servers, including hosted trading through a PreFundedEscrow contract on Polygon. Self-hosted mode runs pmxt-core on your own machine with venue credentials and no PMXT key.
- Hosted writes today: Polymarket, Opinion and Limitless. Kalshi writes require self-hosting with your own RSA key.
- CLI (@pmxt/cli), MCP server (@pmxt/mcp) and React widgets are published alongside the SDKs.
- A dome-to-pmxt codemod migrates code written against the Dome API, which reached end of life on April 28, 2026.
- PyPI shows 322 releases; version 2.54.0 was published July 18, 2026. Python 3.8+ and Node.js 18+ are required.
Pricing
Self-hosting is free under the MIT license. The hosted API is metered by credits: one REST call is one credit and one WebSocket message is 0.1 credits. Health checks are free.
Free: 25,000 credits per month, 60 requests per minute, 5 WebSocket streams, $0. Starter: 250,000 credits, 300 per minute, 20 streams, $29.99 per month. Pro: 1,000,000 credits, 1,000 per minute, 100 streams, $99.99 per month. Enterprise is custom. Limits apply per API key across api.pmxt.dev and trade.pmxt.dev.
Venues and data
The venues page lists 15 targets plus a Kalshi demo target: Polymarket, Kalshi, Limitless, Probable, Baozi, Myriad, Opinion, Metaculus, Smarkets, Polymarket US, Gemini Titan, Hyperliquid, SuiBets, Rain and Hunch. The list is regenerated from pmxt-core's OpenAPI spec on each upgrade.
The pmxt.dev homepage advertises 3+ years of OHLCV history across major venues through the Archive product. The README carries a Zenodo DOI, which matters if you cite the library in research.
Where it falls short
Hosted trading covers three venues. Trading Kalshi through PMXT means running pmxt-core yourself and handing it your Kalshi private key. Hosted mode also puts your USDC in PMXT's escrow contract rather than your wallet, which the docs describe as non-custodial but is still a dependency on their infrastructure.
The Python SDK needs Node.js installed because the self-hosted path spawns pmxt-core, a Node process. The main repo's last push was July 18, 2026, seven weeks before this check, though the hosted docs and rate-limit pages are current.
Who should use it
Bot builders who compare the same event across Polymarket, Kalshi and Limitless, and researchers who want one schema across many venues. Several of the arbitrage bots in the bots directory are built on it.
Skip it if you trade one venue with the official SDK and have no need for cross-venue matching.
Questions about PMXT
Is PMXT free?
Self-hosting is free under MIT. The hosted API has a free tier of 25,000 credits and 60 requests per minute; paid plans are $29.99 and $99.99 per month.
Does PMXT work with Kalshi?
Yes for reads. Kalshi order placement is available only in self-hosted mode with your own Kalshi API key and RSA private key; hosted writes cover Polymarket, Opinion and Limitless.
Is PMXT a replacement for Dome API?
PMXT positions itself as one. It publishes a dome-to-pmxt codemod and a migration guide. Dome itself was acquired by Polymarket and shut its APIs down on April 28, 2026.
What languages does PMXT support?
Python (pip install pmxt) and TypeScript (npm install pmxtjs), plus plain HTTP against api.pmxt.dev for any other language, and a CLI.
Official APIs for building. One book for trading.
Rather trade the spread than build the plumbing? The free Kairos terminal gives you Kalshi, Polymarket and Predict.fun in one order book.