> ## Documentation Index
> Fetch the complete documentation index at: https://docs.whitebit.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Crypto Lending

> Earn yield on crypto assets through fixed-term and flexible lending plans with 13 API endpoints for full lifecycle management.

export const RegionBaseUrl = ({className = "", showBaseUrl = true}) => {
  const [region, setRegionState] = useState(() => {
    if (typeof window !== 'undefined') {
      return localStorage.getItem("api-region-preference") || "com";
    }
    return "com";
  });
  const [mounted, setMounted] = useState(false);
  const observerRef = useRef(null);
  const isSyncingRef = useRef(false);
  const updateAllContentOnPage = targetRegion => {
    try {
      const domainFrom = targetRegion === "eu" ? "whitebit.com" : "whitebit.eu";
      const domainTo = targetRegion === "eu" ? "whitebit.eu" : "whitebit.com";
      const links = document.querySelectorAll('a');
      links.forEach(link => {
        let href = link.getAttribute('href');
        if (href && href.includes(domainFrom)) {
          link.setAttribute('href', href.replace(domainFrom, domainTo));
        }
      });
      const walker = document.createTreeWalker(document.body, NodeFilter.SHOW_TEXT, {
        acceptNode: node => {
          if (node.parentElement?.closest('.region-toggle-component')) {
            return NodeFilter.FILTER_REJECT;
          }
          return node.textContent.includes(domainFrom) ? NodeFilter.FILTER_ACCEPT : NodeFilter.FILTER_REJECT;
        }
      });
      let currentNode;
      while (currentNode = walker.nextNode()) {
        currentNode.textContent = currentNode.textContent.replace(new RegExp(domainFrom, 'g'), domainTo);
      }
      console.log(`[RegionSync] Global content updated to ${domainTo}`);
    } catch (e) {
      console.error("[RegionSync] Error updating content:", e);
    }
  };
  const updateRegion = (newRegion, source) => {
    if (region === newRegion) return;
    console.log(`[RegionBaseUrl] Updating to "${newRegion}" (Source: ${source})`);
    if (source === 'observer') {
      isSyncingRef.current = true;
      setTimeout(() => isSyncingRef.current = false, 1000);
    }
    setRegionState(newRegion);
    localStorage.setItem("api-region-preference", newRegion);
    updateAllContentOnPage(newRegion);
    if (source === 'user-click') {
      window.dispatchEvent(new CustomEvent("regionChange", {
        detail: newRegion
      }));
      attemptToUpdateNativeDropdown(newRegion, 0);
      setTimeout(() => attemptToUpdateNativeDropdown(newRegion, 1), 500);
      setTimeout(() => attemptToUpdateNativeDropdown(newRegion, 2), 1500);
    }
  };
  const attemptToUpdateNativeDropdown = (targetRegion, attempt) => {
    if (isSyncingRef.current) return;
    try {
      const targetUrl = targetRegion === "eu" ? "https://whitebit.eu" : "https://whitebit.com";
      const targetDesc = targetRegion === "eu" ? "EU Server" : "Production Server";
      const selects = document.querySelectorAll('select');
      for (const select of selects) {
        if (select.innerHTML.includes('whitebit.com') || select.innerHTML.includes('whitebit.eu')) {
          select.value = targetUrl;
          select.dispatchEvent(new Event('change', {
            bubbles: true
          }));
          return;
        }
      }
      const buttons = Array.from(document.querySelectorAll('button, [role="combobox"]'));
      const serverSelector = buttons.find(btn => {
        if (btn.closest('a') || btn.closest('[class*="card"]') || btn.closest('nav')) {
          return false;
        }
        const txt = btn.textContent || "";
        const isServerDropdown = (txt.includes('Production Server') || txt.includes('EU Server') || txt.includes('WhiteBIT Global Server') || txt.includes('WhiteBIT EU Server')) && !txt.includes('Run') && !txt.includes('Send') || btn.getAttribute('role') === 'combobox';
        return isServerDropdown;
      });
      if (serverSelector) {
        const currentText = serverSelector.textContent || "";
        if (currentText.includes(targetDesc)) return;
        serverSelector.click();
        setTimeout(() => {
          const options = document.querySelectorAll('[role="option"], li, button');
          for (const opt of options) {
            const optText = opt.textContent || "";
            if (optText.includes(targetDesc) || optText.includes(targetUrl)) {
              opt.click();
              return;
            }
          }
        }, 100);
      }
    } catch (e) {
      console.error("[Sync] Error:", e);
    }
  };
  useEffect(() => {
    setMounted(true);
    updateAllContentOnPage(region);
    const handleStorageChange = e => {
      if (e.key === "api-region-preference" && e.newValue) {
        updateRegion(e.newValue, 'storage');
      }
    };
    const handleRegionChange = e => {
      if (e.detail !== region) {
        updateRegion(e.detail, 'event');
      }
    };
    window.addEventListener("storage", handleStorageChange);
    window.addEventListener("regionChange", handleRegionChange);
    observerRef.current = new MutationObserver(mutations => {
      if (isSyncingRef.current) return;
      updateAllContentOnPage(region);
      for (const mutation of mutations) {
        if (mutation.type !== 'childList' && mutation.type !== 'characterData') continue;
        const target = mutation.target;
        const el = target.nodeType === Node.TEXT_NODE ? target.parentElement : target;
        if (el && (el.getAttribute('role') === 'option' || el.closest('[role="listbox"]'))) continue;
        const text = target.textContent || "";
        if (text.includes('WhiteBIT EU Server') || text.includes('https://whitebit.eu') && text.includes('Server')) {
          if (el && el.tagName !== 'A' && !el.closest('.region-toggle-component')) {
            if (region !== 'eu') updateRegion('eu', 'observer');
          }
        } else if (text.includes('WhiteBIT Global Server') || text.includes('https://whitebit.com') && text.includes('Server')) {
          if (el && el.tagName !== 'A' && !el.closest('.region-toggle-component')) {
            if (region !== 'com') updateRegion('com', 'observer');
          }
        }
      }
    });
    observerRef.current.observe(document.body, {
      childList: true,
      subtree: true,
      characterData: true
    });
    if (typeof window !== 'undefined') {
      const current = localStorage.getItem("api-region-preference");
      if (current) attemptToUpdateNativeDropdown(current, 'init');
    }
    return () => {
      window.removeEventListener("storage", handleStorageChange);
      window.removeEventListener("regionChange", handleRegionChange);
      if (observerRef.current) observerRef.current.disconnect();
    };
  }, [region]);
  const apiBaseUrl = region === "eu" ? "https://whitebit.eu" : "https://whitebit.com";
  if (!mounted) return null;
  return <div className={`flex items-center gap-2 flex-wrap my-4 region-toggle-component ${className}`}>
            <span className="text-sm text-gray-500 dark:text-gray-400 font-mono">
                Base URL
            </span>
            <span className="text-sm text-gray-400">(</span>
            <div className="inline-flex bg-gray-100 dark:bg-gray-800 rounded-lg p-0.5 border border-gray-200 dark:border-gray-700">
                <button onClick={() => updateRegion("com", "user-click")} className={`px-2 py-0.5 text-xs font-medium rounded-md transition-all ${region === "com" ? "bg-white dark:bg-gray-700 text-gray-900 dark:text-gray-100 shadow-sm" : "text-gray-500 dark:text-gray-400 hover:text-gray-900 dark:hover:text-gray-200"}`}>
                    .com
                </button>
                <button onClick={() => updateRegion("eu", "user-click")} className={`px-2 py-0.5 text-xs font-medium rounded-md transition-all ${region === "eu" ? "bg-white dark:bg-gray-700 text-gray-900 dark:text-gray-100 shadow-sm" : "text-gray-500 dark:text-gray-400 hover:text-gray-900 dark:hover:text-gray-200"}`}>
                    .eu
                </button>
            </div>
            <span className="text-sm text-gray-400">)</span>
            {showBaseUrl && <>
                    <span className="text-sm text-gray-400">:</span>
                    <a href={apiBaseUrl} target="_blank" rel="noopener noreferrer" className="text-sm font-mono text-primary dark:text-primary-light hover:underline">
                        {apiBaseUrl}
                    </a>
                </>}
        </div>;
};

<RegionBaseUrl />

Earn yield on crypto assets through fixed-term and flexible lending plans -- 13 API endpoints for full lifecycle management.

## 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](/concepts/balances) assets to work in Flex plans between active trading periods.

## Common Integration Patterns

**Yield-as-a-service** -- Fetch available Flex plans via `POST /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](/concepts/balances) 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                    |

<Note>
  **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.
</Note>

## Technical Overview

* **13 endpoints** total (5 fixed + 8 flex), all `POST`, all authenticated
* **Authentication:** HMAC-SHA512 ([guide](/api-reference/authentication))
* **Rate limits:** 1000 requests per 10 seconds per endpoint ([details](/api-reference/rate-limits))

For full endpoint documentation, see the [Crypto Lending API Reference](/api-reference/account-wallet/overview).

## 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](https://whitebit.com), not the API.

## What's Next

<CardGroup cols={2}>
  <Card title="Quickstart" icon="rocket" href="/products/lending/quickstart">
    Create a first Flex investment in under 5 minutes.
  </Card>

  <Card title="API Reference" icon="square-terminal" href="/api-reference/account-wallet/overview">
    Full endpoint documentation for all 13 lending endpoints.
  </Card>
</CardGroup>