Placing your first order using one of our two Clients is relatively straightforward. For Python: pip install py-clob-client. For Typescript: npm install polymarket/clob-client & npm install ethers. After installing one of those you will be able to run the below code. Take the time to fill in the constants at the top and ensure you’re using the proper signature type based on your login method. 
from py_clob_client.client import ClobClient
from py_clob_client.clob_types import OrderArgs, OrderType
from py_clob_client.order_builder.constants import BUY

host: str = "https://clob.polymarket.com"
key: str = "" #This is your Private Key. Export from https://reveal.magic.link/polymarket or from your Web3 Application
chain_id: int = 137 #No need to adjust this
POLYMARKET_PROXY_ADDRESS: str = '' #This is the address listed below your profile picture when using the Polymarket site.

#Select from the following 3 initialization options to matches your login method, and remove any unused lines so only one client is initialized.


### Initialization of a client using a Polymarket Proxy associated with an Email/Magic account. If you login with your email use this example.
client = ClobClient(host, key=key, chain_id=chain_id, signature_type=1, funder=POLYMARKET_PROXY_ADDRESS)

### Initialization of a client using a Polymarket Proxy associated with a Browser Wallet(Metamask, Coinbase Wallet, etc)
client = ClobClient(host, key=key, chain_id=chain_id, signature_type=2, funder=POLYMARKET_PROXY_ADDRESS)

### Initialization of a client that trades directly from an EOA. 
client = ClobClient(host, key=key, chain_id=chain_id)

## Create and sign a limit order buying 5 tokens for 0.010c each
#Refer to the Markets API documentation to locate a tokenID: https://docs.polymarket.com/developers/gamma-markets-api/get-markets

client.set_api_creds(client.create_or_derive_api_creds()) 

order_args = OrderArgs(
    price=0.01,
    size=5.0,
    side=BUY,
    token_id="", #Token ID you want to purchase goes here. 
)
signed_order = client.create_order(order_args)

## GTC(Good-Till-Cancelled) Order
resp = client.post_order(signed_order, OrderType.GTC)
print(resp)

​
In addition to detailed comments in the code snippet, here are some more tips to help you get started.

  • See the Python example for details on the proper way to intialize a Py-Clob-Client depending on your wallet type. Three exhaustive examples are given. If using a MetaMask wallet or EOA please see the resources here, for instructions on setting allowances.
  • When buying into a market you purchase a “Token” that token represents either a Yes or No outcome of the event. To easily get required token pairs for a given event we have provided an interactive endpoint here.
  • Common pitfalls:
    • Negrisk Markets require an additional flag in the OrderArgs negrisk=False
    • invalid signature error, likely due to one of the following.
      • Incorrect Funder and or Private Key
      • Incorrect NegRisk flag in your order arguments
    • not enough balance / allowance.
      • Not enough USDC to perform the trade. See the formula at the bottom of this page for details.
      • If using Metamask / WEB3 wallet go here, for instructions on setting allowances.