eth_getTransactionByBlockHashAndIndex — Polygon JSON-RPC

eth_getTransactionByBlockHashAndIndex looks up a Polygon block by its 32-byte hash and returns the one transaction sitting at the supplied zero-based index within that block. The transaction comes back as the standard Ethereum/Bor transaction object.

Use it when you already hold a block hash — from a log, a receipt's blockHash, or a prior eth_getBlockByHash response — and want to walk that block's transactions one at a time without downloading the full block body. It is a common primitive for block-by-block indexers: pair it with eth_getBlockTransactionCountByHash to read the transaction count, then iterate 0x0 … count-1, fetching each transaction by index. Addressing by hash (rather than by number) is unambiguous — a hash pins exactly one block even across a reorganization.

If the block hash is unknown to the node (for example a block it has not yet seen, or one orphaned by a reorg) or the index is out of range for the block, the method succeeds and returns null rather than an error. Always check for null before reading fields off the result.

Positional params array: [blockHash, index].

When the block hash is unknown or the index is out of range, the result is null:

{
  "jsonrpc": "2.0",
  "id": 1,
  "result": null
}

An unknown block hash or an out-of-range index is not an error — it is reported as result: null (see above). Every error follows the shared JSON-RPC error envelope — see Errors for the full structure and handling guidance.

JavaScript (fetch)

const res = await fetch("https://triport.io/polygon", {
  method: "POST",
  headers: {
    "Authorization": `Bearer ${process.env.TRIPORT_API_KEY}`,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    jsonrpc: "2.0",
    id: 1,
    method: "eth_getTransactionByBlockHashAndIndex",
    params: [
      "0x9b7f2a3c1d4e5f60718293a4b5c6d7e8f90123456789abcdef0123456789abcd",
      "0x0",
    ],
  }),
});


const { result } = await res.json();
console.log(result === null ? "no transaction at that index" : result.hash);

• index is hex, not decimal. Pass 0x0, 0x1, … — not 0, 1.
• Always handle null. An unknown block hash or an out-of-range index returns result: null rather than an error. Guard for it before reading any field.
• Indexer iteration pattern. Read the transaction count with eth_getBlockTransactionCountByHash, then request indices 0x0 through count-1. When you need every transaction in a block at once, fetching the full block with eth_getBlockByHash (fullTxBodies = true) is cheaper than many per-index calls.
• EIP-1559 fee fields. maxFeePerGas and maxPriorityFeePerGas appear only on type 0x2 transactions; legacy transactions expose gasPrice only.
• Rate limiting is RPS-per-tier with a burst allowance; there is no daily quota. An HTTP 429 rate_limited response means you should back off and retry shortly.
• Related methods: eth_getTransactionByBlockNumberAndIndex (same lookup by block number), eth_getTransactionByHash (look up directly by transaction hash), eth_getBlockTransactionCountByHash.