Capabilities
The Crypto Lending API supports two plan types with distinct yield mechanics.- Fixed plans — lock assets for 10-360 day terms. Interest paid at maturity. Interest ratio conversion when target currency differs from source currency.
- Flexible plans — deposit and withdraw anytime. Interest calculated hourly, credited daily. Auto-reinvestment option compounds returns.
- ~90 supported assets — invest in a wide range of crypto assets (check available plans dynamically via the plans endpoint)
- Auto-invest — configure automatic recurring investments into Flex plans
- Full lifecycle API — create, monitor, withdraw, and close investments programmatically
Who Uses This
- Yield integrators — fintechs and platforms offering lending products to end users via API. Fetch available plans, create investments on behalf of customers, track earnings.
- Treasury operations — exchanges and trading firms putting idle Main balance assets to work in Flex plans between active trading periods.
Common Integration Patterns
Yield-as-a-service — Fetch available Flex plans viaPOST /api/v4/main-account/smart-flex/plans. Present plan options (asset, interest rate) to end users. Create investments via POST /api/v4/main-account/smart-flex/investments/invest. Track earnings through POST /api/v4/main-account/smart-flex/investments/payment-history. Enable auto-reinvestment for compounding.
Idle asset management — Monitor Main balance for idle assets. Invest surplus into Flex plans (withdraw anytime, no lock-up). Set up auto-invest for recurring allocation. Withdraw back to Main balance before trading.
Plan Types
| Feature | Fixed Plans | Flex Plans |
|---|---|---|
| Lock-up | 10, 20, 30, 90, 180, or 360 days | None (withdraw anytime) |
| Interest | Paid at maturity | Calculated hourly, credited daily |
| Early withdrawal | Allowed — but interest is forfeited | Allowed — accrued interest is retained |
| Auto-reinvest | N/A | Available |
| Auto-invest | N/A | Available |
| API access | B2B partners only | All authenticated users |
Fixed plan API access: Fixed lending endpoints (
/api/v4/main-account/smart/) require B2B partner
permissions. Complete the institutional services form to request access. Flex endpoints
(/api/v4/main-account/smart-flex/) are available to all authenticated users.Technical Overview
- 13 endpoints total (5 fixed + 8 flex), all
POST, all authenticated - Authentication: HMAC-SHA512 (guide)
- Rate limits: 1000 requests per 10 seconds per endpoint (details)
Platform Context
The WhiteBIT platform brands lending products as U EARN. The platform also offers Staking and Auto-Invest for recurring purchases — available via the platform UI, not the API.What’s Next
Quickstart
Create a first Flex investment in under 5 minutes.
API Reference
Full endpoint documentation for all 13 lending endpoints.