Official venue APIsAPIfree
Limitless API: what it exposes, how it authenticates, where it stops
Last checked 2026-09-08
Limitless Exchange runs prediction markets on Base (chain ID 8453) with both an order book and AMM markets, and exposes them through REST at https://api.limitless.exchange and a Socket.IO WebSocket at wss://ws.limitless.exchange. Individual traders need no application; partners running sub-accounts do.
It is for developers who want to place their own orders from a bot or agent with typed SDKs, and who accept that every test happens on mainnet with real USDC.
What the API exposes
REST covers market discovery (for example GET /markets/active and GET /markets/{slug} with venue data), order books, order creation and cancellation on CLOB markets, portfolio and positions, scoped token management, partner sub-accounts and delegated orders. NegRisk category markets are supported.
AMM markets have intent-level endpoints (POST /amm/buy, /amm/sell, allowance check and approve) for server-wallet sub-accounts, with slippage in basis points, default 100 and maximum 1,000.
The WebSocket delivers newPriceData, orderbookUpdate and system events without auth, and positions updates on an HMAC-signed handshake. Interactive Scalar docs live at /api-v1, and a migrate-from-Polymarket guide maps concepts and endpoints.
Authentication and rate limits
Every request is signed with a scoped API token: headers lmts-api-key, lmts-timestamp (ISO-8601, within 30 seconds of server time) and lmts-signature, an HMAC-SHA256 over timestamp, method, full path with query string and body. Scopes are trading, account_creation, delegated_signing and withdrawal. Legacy x-api-key keys are deprecated for new users.
Orders themselves are EIP-712 signed with the domain Limitless CTF Exchange, chain 8453, using the market venue's exchange address as verifyingContract. Accounts that ever enabled 1-click smart-wallet trading must switch the profile to EOA mode before API orders work.
Rate limits are enforced with 429 responses and a Retry-After header, but the numbers are not published. The TypeScript SDK ships an OrderQueue for throttling.
Pricing and access
No API fee. Tokens come from limitless.exchange, profile menu, Api keys. SDKs: @limitless-exchange/sdk (npm), limitless-sdk (PyPI, async), a Go module and a Rust crate, all under limitless-labs-group on GitHub.
Fees hit takers only. AMM trades pay a flat 0.40%. CLOB buys pay 3.00% at prices up to $0.50 falling to 0.40% at $0.999, in outcome tokens; CLOB sells peak at 1.50% at $0.50 and fall toward 0.42% at the extremes, in USDC. Resting limit orders pay nothing.
Where it falls short
The docs are explicit: no sandbox, testnet, mock mode or Base Sepolia deployment. The suggested rehearsal is a minimum-size live order on a quiet market.
Buying low-probability outcomes as a taker costs 3.00%, which is steep next to Polymarket or Kalshi.
Unpublished rate limits and the wallet-mode gotcha are the two things that stall first integrations.
Who should use it
Agent and bot authors on Base who want self-serve access and SDKs in four languages, and market makers who can trade fee-free by resting orders.
Anyone who needs a test environment before risking capital should start elsewhere.
Questions about Limitless API
Does Limitless have a testnet?
No. The developer docs state there is no sandbox, testnet, mock mode or Base Sepolia deployment; all integrations run on Base mainnet with real USDC.
How do I authenticate with the Limitless API?
Generate a scoped API token in the profile menu and HMAC-SHA256 sign every request with lmts-api-key, lmts-timestamp and lmts-signature headers. Orders are also EIP-712 signed.
What are Limitless trading fees?
Takers only. 0.40% flat on AMM markets; on the order book, buys range 0.40% to 3.00% and sells 0.42% to 1.50% depending on price. Makers pay nothing.
Is there a Limitless SDK?
Yes: @limitless-exchange/sdk for TypeScript, limitless-sdk for Python, plus official Go and Rust SDKs.
Official APIs for building. One book for trading.
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