LMEX provides three API protocols for programmatic access to its spot and futures markets: REST, WebSocket, and FIX. Each serves a different role in a trading system’s architecture, and choosing the right combination for your use case is the first decision any developer or algorithmic trader should make.
This article is an overview of the available protocols, their primary use cases, and the key endpoint and authentication conventions. Full technical documentation is at docs.lmex.io.
REST API
The REST API is the standard choice for order management, account queries, and operations where a confirmed response is required before proceeding. It operates on a request-response model — your application sends an HTTP request to an endpoint, the server returns a structured response.
LMEX’s REST API covers:
- Order placement, modification, and cancellation (spot and futures)
- Account and wallet data queries
- Market data including order book snapshots, trade history, and pricing
- Position and margin information
- OTC desk operations
- Earn programme endpoints
Current base URLs:
- Spot:
https://api.lmex.io/spot/api/v3.3/ - Futures:
https://api.lmex.io/futures/api/v2.3/
The futures API version is v2.3, applicable to accounts that have upgraded to the Unified Futures Wallet. The spot API is v3.3. Market summary data is publicly accessible without authentication at these endpoints; private endpoints require signed requests.
WebSocket API
The WebSocket protocol maintains a persistent connection between your client and the LMEX server, enabling the server to push real-time data without repeated polling from your application. This makes WebSocket the appropriate choice for:
- Live order book streaming
- Real-time trade feed subscriptions
- Mark price and index price updates
- Account balance and position change notifications
- Funding rate updates
For any strategy that depends on real-time market data — grid bots, momentum strategies, arbitrage systems — WebSocket is the preferred data source. Polling the REST API for order book updates at high frequency is both inefficient and subject to rate limiting. WebSocket solves this cleanly with a persistent, low-overhead connection.
Public WebSocket channels (market data) do not require authentication. Private channels (account data, position updates, order events) require HMAC SHA256 authentication.
FIX API
FIX (Financial Information eXchange) is the protocol standard used by institutional traders, prime brokers, and professional execution infrastructure. LMEX supports FIX API for both spot and futures, enabling integration with standard institutional connectivity layers.
For retail and algorithmic traders, FIX is generally only relevant if you are connecting existing institutional infrastructure that mandates the protocol. For most use cases, REST and WebSocket provide everything needed with simpler implementation.
Authentication
Private API endpoints require authentication via HMAC SHA256:
- Construct the message string: typically timestamp + HTTP method + endpoint path + request body.
- Sign using your API secret as the HMAC key.
- Include the API key, signature, and timestamp in the request headers.
API keys are generated from your account settings page. Each key supports granular permission scoping — read-only, trading, or withdrawal. For any key used by a trading bot, never grant withdrawal permissions. Restrict permissions to the minimum required for the bot’s function and whitelist specific IP addresses where possible.
Futures Symbol Conventions
All futures symbols on the v2.3 API use the XXX-PERP format for perpetual contracts:
- BTC perpetual:
BTC-PERP - ETH perpetual:
ETH-PERP - SOL perpetual:
SOL-PERP
Time-based (quarterly) contracts use a date suffix format, as seen in the live market data: BTC-260327 (expiring 27 March 2026), BTC-260626 (expiring 26 June 2026).
Market fields in responses use XXX-PERP-USDT. Isolated wallet names use ISOLATED@XXX-PERP-USDT. Ensure your parsing logic accounts for these formats if you are migrating from older API versions.
Rate Limits and Spam Prevention
LMEX operates a spam order prevention mechanism on the matching engine to protect overall market performance. Accounts sending high volumes of small orders in rapid succession may have rate limits, position limits, or API access restricted.
Strategies generating many small orders — particularly grid bots with very narrow spacing — should implement appropriate throttling and minimum order sizing to avoid triggering this mechanism. For detailed rate limit specifications, refer to docs.lmex.io.
Public Market Data Endpoints
Two public REST endpoints provide live market summary data without requiring authentication:
- Spot markets:
https://api.lmex.io/spot/api/v3.3/market_summary - Futures markets:
https://api.lmex.io/futures/api/v2.3/market_summary
These return comprehensive data per symbol including last price, bid/ask, 24-hour volume, open interest, funding rate (futures), contract size, available settlement currencies, and position limits. They are useful for monitoring available markets and building market overview tools without requiring an account.
Getting Support
For technical API queries, use the LMEX support portal at lmex.freshdesk.com. For institutional API arrangements — custom rate limits, co-location, or bespoke integrations — contact business@lmex.io.
Frequently Asked Questions
Which API version should I use for futures? v2.3 is the current live version for accounts on the Unified Futures Wallet. Full documentation is at docs.lmex.io.
How do I generate an API key? Log in to LMEX, navigate to account settings, and find the API key management section. Create a key, assign permissions, optionally whitelist IPs, and store your secret securely — it is displayed only once at creation.
Does LMEX support market data access without authentication? Yes. Public endpoints for spot and futures market summaries, order book snapshots, and recent trade data are accessible without authentication.
Are WebSocket and REST available for both spot and futures? Yes. Both protocols cover spot and futures markets. FIX is also supported across both. See docs.lmex.io for the full endpoint reference.
