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

# Transaction Indexing

> How to integrate Relay’s transaction indexing APIs

## Overview

Relay provides two key APIs for transaction indexing:

* [transactions/single](/references/api/transactions-single) - For indexing same-chain transfers, wraps, and unwraps
* [transactions/index](/references/api/transactions-index) - For accelerating indexing of transactions with internal deposits

## API 1: transactions/single

### When to Use

Use this API for **same-chain actions** including:

* Token transfers
* Token wraps (e.g., ETH to WETH)
* Token unwraps (e.g., WETH to ETH)

Note: This is not required for same-chain swaps.

### Purpose

* Ensures same-chain actions are properly indexed
* Relay's indexer doesn't actively monitor same-chain actions by default
* Critical for applications supporting same-chain token operations

### API Reference

[Documentation](/references/api/transactions-single)

[Implementation Reference](https://github.com/reservoirprotocol/relay-kit/blob/main/packages/sdk/src/utils/transaction.ts#L122)

### Request Example

```bash theme={null}
curl -X POST 'https://api.relay.link/transactions/single' \
  -H 'Content-Type: application/json' \
  -d '{
  "tx": "{\"from\":\"0x03508bB71268BBA25ECaCC8F620e01866650532c\",\"to\":\"0x3c499c542cef5e3811e1192ce70d8cc03d5c3359\",\"data\":\"0xa9059cbb00000000000000000000000036329d1ff4b31ec85280a86e7cf58fca7c005ed000000000000000000000000000000000000000000000000000000000000f4240\",\"value\":\"0\",\"chainId\":137,\"gas\":\"94464\",\"maxFeePerGas\":\"34643644476\",\"maxPriorityFeePerGas\":\"34180692255\",\"txHash\":\"0x935be17e13f1dc4aee15e75cc9c119f2d639e58b061a54246843f2ddf1052f7c\"}",
  "chainId":"137",
  "requestId":"0xcb6bec4106d2bc6f692831e00445f843fa39239ca61bc304486b0c96e1d531a9"
}'
```

## API 2: transactions/index

### When to Use

Use this API for transactions that contain internal deposits that need to be detected through trace analysis. This is particularly important for teams using their own proxy contracts.

### Purpose

* Accelerates the indexing process by triggering indexing before transaction validation completes
* Ensures Relay fetches transaction traces to detect internal deposits
* Recommended for custom proxy contract implementations

### API Reference

[Documentation](/references/api/transactions-index)

[Implementation Reference](https://github.com/reservoirprotocol/relay-kit/blob/main/packages/sdk/src/utils/transaction.ts#L113)

### Request Example

```bash cURL theme={null}
curl -X POST 'https://api.relay.link/transactions/index' \
  -H 'Content-Type: application/json' \
  -d '{
  "txHash": "0x9f2c5e8b1d4a7f0c3e6b9d2f5a8c1e4b7d0a3f6c9e2b5d8a1f4c7e0b3d6a9f2c",
  "chainId": 8453
}'
```

### Integration

Call this API immediately after submitting a transaction, before waiting for confirmation.

## Decision Matrix

| Transaction Type            | API Endpoint          | Reason                                             |
| --------------------------- | --------------------- | -------------------------------------------------- |
| Cross-chain transactions    | `transactions/index`  | Accelerates indexing before validation             |
| Proxy contract transactions | `transactions/index`  | Detects internal deposits via trace analysis       |
| Same-chain swaps            | `transactions/index`  | Accelerates indexing and detects internal deposits |
| Same-chain token transfers  | `transactions/single` | Not actively monitored by default indexer          |
| ETH ↔ WETH wraps/unwraps    | `transactions/single` | Same-chain operations need explicit indexing       |

## Key Takeaways

1. **transactions/single** is essential for same-chain operations that aren't automatically monitored
2. **transactions/index** is for accelerating indexing of transactions with internal deposits
3. Call these APIs immediately after transaction submission for optimal indexing performance
4. Choose the appropriate API based on your transaction type using the decision matrix above

For detailed implementation examples, refer to the Relay SDK source code links provided above.