Polymarket API client for Python

A small, typed Python toolkit for the Polymarket API. Read markets from the Gamma API, snapshot and stream the Polymarket CLOB order book, generate idempotent client order ids, and place orders through Polymarket's official client (py-clob-client).

It wraps Polymarket's public CLOB and Gamma APIs. The read / stream / analytics surface needs only httpx and websockets and no API key. Order placement is opt-in.

pip install polymarket-api-python

30-second quickstart

Read the most-active market right now and check its order book — no credentials required:

from polymarket_api import GammaClient, fetch_order_book

with GammaClient() as gamma:
    # Markets sorted by 24h volume; grab the busiest one.
    market = next(iter(gamma.iter_markets(max_markets=1)))

print(market.question)

book = fetch_order_book(market.yes_token_id)
print(f"YES  bid={book.best_bid}  ask={book.best_ask}  spread={book.spread_bps:.0f} bps")
print(f"depth within 5% of mid:  bid={book.bid_depth_5pct}  ask={book.ask_depth_5pct}")

Will <…> happen by <…>?
YES  bid=0.62  ask=0.63  spread=160 bps
depth within 5% of mid:  bid=4210.0  ask=3880.0

What it does

Stream live prices

import asyncio
from polymarket_api import ClobWebSocketClient, PriceChange

async def main():
    client = ClobWebSocketClient()

    async def on_event(event):
        if isinstance(event, PriceChange):
            print(event.token_id[:12], event.best_bid, event.best_ask)

    # Runs forever, reconnecting as needed. Ctrl-C to stop.
    await client.run(["<clob_token_id>"], on_event)

asyncio.run(main())

Place an order (optional)

Order placement is opt-in and pulls in Polymarket's official, audited client, which performs all EIP-712 signing:

pip install "polymarket-api-python[trading]"

import os
from polymarket_api.orders import make_trading_client, place_limit_order

client = make_trading_client(os.environ["POLYMARKET_PRIVATE_KEY"])  # derives L2 creds for you
place_limit_order(client, token_id="<clob_token_id>", price=0.40, size=20, side="BUY")

This package never implements signing itself — see docs/sign-and-place-an-order.md.

Docs / Cookbook

Task-oriented, code-first recipes — each is a runnable snippet plus the gotchas that bite in production:

• Read markets — list and filter Gamma markets, decode the string-encoded fields
• Order book snapshots — spread, depth, and liquidity from one call
• WebSockets — stream prices and book updates with auto-reconnect
• Sign and place an order — L1/L2 auth and the official client
• Cancel and replace — idempotent ids and the cancel/replace pattern
• Auth and keys — what L1 vs L2 actually mean
• Rate limits — the real per-endpoint limits and how to stay under them
• Handling resolution — detect when a market settles

Install from source

git clone https://github.com/antflow-live/polymarket-api-python
cd polymarket-api-python
pip install -e ".[dev]"
pytest

About antflow

This toolkit is maintained by antflow — an autonomous trading bot for Polymarket. antflow scans prediction markets, applies operator-defined risk controls, and executes and monitors trades automatically. We open-sourced the generic API plumbing we rely on so other Polymarket developers don't have to rebuild it.

• Website: https://antflow.live
• LinkedIn: https://www.linkedin.com/company/antflow-live
• Crunchbase: https://www.crunchbase.com/organization/antflow

Disambiguation: this is antflow — Polymarket trading. It is unrelated to antflow.ai and to the AntFlow workflow-engine projects that share the name.

Disclaimer

This is developer tooling for the Polymarket API, provided for educational and informational purposes only. It is not financial advice and makes no representation about trading outcomes or profitability. Prediction-market trading carries risk. Comply with Polymarket's terms and the laws of your jurisdiction. Use at your own risk; see the MIT License for warranty terms.

License

MIT © 2026 antflow