Authentication

API Key Authentication

All programmatic access to the Limitless Exchange API requires an API key.

Cookie-based session authentication is deprecated and will be removed soon. Migrate to API keys immediately.

Go to limitless.exchange and connect your wallet.

Open API key settings

Click your profile menu (top right) → select “Api keys”.

Generate a new key

Create a new key. It will start with lmts_....

Include the key in all requests via the X-API-Key header:

# REST API
curl -H "X-API-Key: lmts_your_key_here" https://api.limitless.exchange/markets

# WebSocket - pass as header during connection handshake

Method	Header	Status
API Key	`X-API-Key: lmts_...`	Required for programmatic access
Cookie Session	`Cookie: limitless_session=...`	Deprecated (removal imminent)

# Before (deprecated)
- Cookie: limitless_session=your_session_token

# After (recommended)
+ X-API-Key: lmts_your_key_here

No more login flow or cookie handling needed.

All Ethereum addresses in API requests must use checksummed format (EIP-55 mixed-case):

Example: 0x5aAeb6053F3E94C9b9A09f33669435E7Ef1BeAed

Your private key is still required for EIP-712 order signing, but the API key handles request authentication.