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Base Chain On-Chain Event Log Decoder
x402
Base Chain On-Chain Event Log Decoder is a paid API for AI agents from x402-endpoints.onrender.com, paid per call via x402, $0.05/call, status unknown (last checked 2026-09-14).
Query and decode on-chain event logs for any contract on Base, returning normalized human-readable events (Transfer, Approval, Swap, Mint, Burn, ERC-1155, Uniswap V2/V3) without requiring RPC setup.
Price / call$0.05
Success—
StatusUnknown
How this service works
On-demand, decoded on-chain events for AI agents: query a contract's event logs on Base (eth_getLogs) and get normalized, human-readable events — Transfer, Approval, ERC-1155 TransferSingle/Batch, Uniswap V2/V3 Swap, Sync, Mint, Burn — with raw topics for unknown signatures. Filter by event name, full signature or topic0, and by block range or lookback. Decoded event feed with no RPC setup, block span capped.
Output
A list of decoded, human-readable on-chain events from the specified contract on Base, including event name, parsed arguments, block number, transaction hash, and log index. Known event types (Transfer, Approval, Swap, Mint, Burn, Sync, TransferSingle, TransferBatch) are fully decoded; unknown signatures return raw topic arrays.
Example use cases
Example prompt
“Can you pull the last 50 decoded Transfer events for contract 0xd9aAEc86B65D86f6A7B5B1b0c42FFA531710b6CA on Base, looking back 3000 blocks?”
Technical details
Endpoint
GEThttps://x402-endpoints.onrender.com/chain/eventsWhen to prefer
Use this endpoint when you need decoded, human-readable on-chain events from a Base contract without managing your own RPC node or writing eth_getLogs queries. Ideal for AI agents that need to understand token transfers, DeFi swap activity, NFT mints/burns, or ERC-1155 batch transfers for a specific contract, especially when you want normalized output rather than raw hex logs.
Side effects
- Invalid contract address format (must be 0x + 40 hex chars) — returns 400
- Block range exceeds cap — returns error with allowed span limit
- No events found in the specified range — returns empty list
- Lookback value out of range (must be 1–5000) — returns 400
- Limit out of range (must be 1–100) — returns 400
- Network or RPC backend error — returns 5xx
Input
Schema · Request body
| Field | Type | Description |
|---|---|---|
| inputrequired | object | |
| output | object |
Output
Schema · Response
{
"type": "json",
"example": {
"rpc": {
"provider": "alchemy",
"fallback_used": false
},
"count": 1,
"query": {
"event": "Transfer",
"limit": 10,
"topic0": "0xddf252ad...b3ef",
"contract": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"lookback": 500,
"to_block": 33810500,
"from_block": 33810000
},
"cached": false,
"events": [
{
"event": "Transfer",
"params": {
"to": "0x2222...",
"from": "0x1111...",
"value": 1500000
},
"topic0": "0xddf252ad...b3ef",
"address": "0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913",
"decoded": true,
"tx_hash": "0xabc...",
"log_index": 12,
"signature": "Transfer(address,address,uint256)",
"block_number": 33810480
}
],
"source": "Base JSON-RPC eth_getLogs (Alchemy, fallback public RPC)",
"decoders": [
"Approval",
"Burn",
"Mint",
"Swap(V2)",
"Swap(V3)",
"Sync",
"Transfer",
"TransferBatch",
"TransferSingle"
],
"timestamp": "2026-07-02T12:00:00Z",
"truncated": false,
"disclaimer": "Decoded from public on-chain logs; unknown event signatures are returned raw. Block span and result count are capped.",
"block_range": {
"span": 500,
"to_block": 33810500,
"from_block": 33810000,
"latest_block": 33810500
},
"total_in_range": 1
}
}Tags
x402
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