Standalone Elixir client for the Polymarket CLOB API.

This package owns the low-level CLOB surface only — auth, EIP-712 order signing, order placement, balances, order books, prices, and per-market metadata. Higher-level Polymarket features (Gamma market discovery, Data API normalization, RTDS, CTF, pUSD) are intentionally out of scope and live in separate packages.

Layered API

The recommended usage pattern is to call the API submodules directly. This module exposes only a small client-construction shorthand and a version helper; it intentionally does not shadow the layered API.

• PolymarketClob.Client — client struct, address derivation, signature-type defaults.
• PolymarketClob.Config — chain IDs, contract addresses, side and signature-type constants.
• PolymarketClob.API.MarketData — public reads (markets, books, prices, fees, neg-risk, simplified/sampling lists, live activity).
• PolymarketClob.API.Account — private reads (balances/allowances, orders, trades, scoring, notifications).
• PolymarketClob.API.Orders — order placement and cancellation (POST/DELETE).
• PolymarketClob.Order.Builder — local Python-parity amount calculation and signed-order construction.
• PolymarketClob.Order.Signing — EIP-712 typed-data, order hash, and signature.
• PolymarketClob.Order.Rounding — float-based rounding helpers ported from py-clob-client-v2.
• PolymarketClob.Auth.L1 — EIP-712 ClobAuth (with v2 nonce).
• PolymarketClob.Auth.L2 — HMAC-SHA256 request signing.
• PolymarketClob.HTTP — Req-based transport layer (rarely called directly).
• PolymarketClob.Error — normalized error struct returned by all API helpers.

See ENDPOINT_COVERAGE.md for the full HTTP endpoint mapping against the audited Polymarket/py-clob-client-v2 commit.

Quick start

client =
  PolymarketClob.client(
    private_key: System.fetch_env!("POLY_PRIVATE_KEY"),
    api_key: System.get_env("POLY_API_KEY"),
    api_secret: System.get_env("POLY_API_SECRET"),
    api_passphrase: System.get_env("POLY_API_PASSPHRASE")
  )

{:ok, book} = PolymarketClob.API.MarketData.get_order_book("123456")
{:ok, balance} = PolymarketClob.API.Account.get_balance_allowance(client)

See PolymarketClob.Client.new/1 for the full option list and signature-type auto-detection rules. With API credentials present, the client defaults to signature type 2 (Polymarket Gnosis Safe). Without them, it defaults to 0 (EOA).

Parity with py-clob-client-v2

Order amount calculation, EIP-712 signing, ClobAuth-with-nonce, and HMAC L2 request signing are validated against deterministic fixtures generated from the official Python client. See test/fixtures/parity/ and scripts/generate_parity_fixtures.py.