alchemy-rate-limits

# Alchemy Rate Limits ## Overview Alchemy uses Compute Units (CU) to measure API usage. Different methods cost different CU amounts. Rate limits are per-second, and exceeding them returns 429 errors. ## Compute Unit Costs | Method | CU Cost | Category | |--------|---------|----------| | `eth_blockNumber` | 10 | Core | | `eth_getBalance` | 19 | Core | | `eth_call` | 26 | Core | | `eth_getTransactionReceipt` | 15 | Core | | `getTokenBalances` | 50 | Enhanced | | `getTokenMetadata` | 50 | Enhanced | | `getAssetTransfers` | 150 | Enhanced | | `getNftsForOwner` | 50 | NFT | | `getNftMetadataBatch` | 50 | NFT | | `getContractMetadata` | 50 | NFT | ## Plan Limits | Plan | CU/sec | Monthly CU | Price | |------|--------|------------|-------| | Free | 330 | 300M | $0 | | Growth | 660 | 1.2B | $49/mo | | Scale | Custom | Custom | Custom | ## Instructions ### Step 1: CU-Aware Request Throttler ```typescript // src/alchemy/throttler.ts import Bottleneck from 'bottleneck'; const CU_COSTS: Record<string, number> = { 'eth_blockNumber': 10, 'eth_getBalance': 19, 'eth_call': 26, 'getTokenBalances': 50, 'getAssetTransfers': 150, 'getNftsForOwner': 50, }; // Free tier: 330 CU/sec = ~16 getBalance calls/sec const limiter = new Bottleneck({ reservoir: 330, // CU budget per interval reservoirRefreshInterval: 1000, // Refresh every second reservoirRefreshAmount: 330, // Reset to max CU/sec maxConcurrent: 10, // Max parallel r...