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Self-hosted PMXT runs the open-source pmxt-core server on your machine. The SDK detects the absence of a pmxt_api_key and routes through http://localhost:3847 instead of trade.pmxt.dev. Venue credentials stay on your machine; you talk to venue APIs directly.

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When self-hosted is the right call

Pick self-hosted if any of these apply:
  • Sub-100ms latency — local submission removes a network hop. Matters for latency-sensitive arb / market-making.
  • Raw venue credentials — Polymarket L2 API keys, Kalshi RSA, Smarkets session cookies. Hosted mode doesn’t accept these.
  • Regulatory custody — you must be the direct counterparty with no intermediary in the custody path.
  • Venues hosted mode can’t write to yet — hosted writes are Polymarket, Opinion, and Limitless. Self-hosted can use venue-native credentials where the venue exposes writes (Kalshi, Smarkets, Probable, Myriad, Metaculus, etc.); check Feature Support & Compliance for per-venue support.
  • OSS contribution — you’re hacking on pmxt-core itself.

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When hosted is still the better choice

Everyone else. Hosted is simpler to deploy (no local process), gives you on-chain custody you control via the timelock, and PMXT’s server never sees a private key. If you’re building a consumer app, a research notebook, or any non-latency-critical service against Polymarket, Opinion, or Limitless, stop here and use hosted.

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1. Install pmxt-core

The SDK installs and supervises pmxt-core for you. You don’t run a separate binary; the SDK spawns it as a child process on first use. 
pip install pmxt

npm install pmxtjs
That’s it — pmxt-core is bundled.

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2. Construct without an API key

Drop the pmxt_api_key argument. The SDK detects the absence and starts the local server. 
import pmxt

# No pmxt_api_key → SDK spawns and supervises pmxt-core locally
poly = pmxt.Polymarket()

markets = poly.fetch_markets(query="election", limit=3)

import { Polymarket } from "pmxtjs";

// No pmxtApiKey → SDK spawns and supervises pmxt-core locally
const poly = new Polymarket({});

const markets = await poly.fetchMarkets({ query: "election", limit: 3 });
The first call blocks briefly while the local server warms up; subsequent calls reuse the process.

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3. Manage the local server

For lifecycle control (start, stop, restart, status, logs), use the server namespace. See Server Management for the full reference. 
import pmxt

pmxt.server.start()       # idempotent
pmxt.server.health()      # bool
pmxt.server.status()      # structured snapshot
pmxt.server.stop()
pmxt.server.restart()
pmxt.server.logs(20)
Most users never call these — creating an exchange instance auto-starts the server.

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4. Per-venue raw credentials

Self-hosted unlocks the full venue-credential surface. Pass credentials directly to the exchange constructor.

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Polymarket — EVM private key

import pmxt

poly = pmxt.Polymarket(private_key="0xYourPrivateKey...")

order = poly.create_order(
    outcome=market.yes,
    side="buy",
    order_type="limit",
    price=0.42,
    amount=100,
)

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Kalshi — RSA key pair

import pmxt

kalshi = pmxt.Kalshi(
    api_key_id="...",
    private_key_pem="-----BEGIN RSA PRIVATE KEY-----\n...",
)

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Limitless / Probable / Opinion (self-hosted) — EVM private key

import pmxt

limitless = pmxt.Limitless(private_key="0x...")
probable  = pmxt.Probable(private_key="0x...")
opinion   = pmxt.Opinion(private_key="0x...")

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Smarkets — email + password

import pmxt

smarkets = pmxt.Smarkets(email="you@example.com", password="...")

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Baozi — Solana keypair

import pmxt

baozi = pmxt.Baozi(private_key="<base58 secret key>")
See Supported Venues for the full credential matrix.
For venues that use a fund-controlling private key (Polymarket, Limitless, Probable, Opinion, Baozi), a practical habit is to keep only the float you’re actively trading in this wallet.

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5. Environment overrides

VariableEffect
PMXT_LOCAL_PORT=3847Override the local server port (default 3847).
PMXT_ALWAYS_RESTART=1Force-restart the local server on every ensure_server_running call. Useful during development.
PMXT_BASE_URLPoint the SDK at a custom server URL (advanced — defaults to http://localhost:3847).
See API Reference / Configuration for the full env-var matrix.

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6. Running multiple exchanges

A single pmxt-core process can serve every venue. Construct multiple exchange clients against the same server — they all share the local process. 
import pmxt

poly = pmxt.Polymarket(private_key="0x...")
kalshi = pmxt.Kalshi(api_key_id="...", private_key_pem="...")
# Both clients reuse the same pmxt-core process at http://localhost:3847

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7. Production deployment

For production self-hosted, the SDK + bundled server is sufficient — there’s no separate daemon to manage. If you want to run pmxt-core as a long-lived process with systemd or similar, see the pmxt-core README for standalone server commands.

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What you give up vs hosted

  • Cross-venue search via Router — still works, but requires the hosted pmxt_api_key for the catalog. If you want Router without trading-hosted, construct a separate Router client with the API key alongside your local trading clients. See Hosted trading.
  • Hosted error tree — you’ll get the parent classes (InvalidOrder, InsufficientFunds) but not the hosted leaves. Catching parents keeps your code portable.
  • PreFundedEscrow custody — irrelevant in self-hosted; you custody at the venue.

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