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

# tryLocateSourceTx | TON v2

> The tryLocateSourceTx method attempts to locate the source transaction in the TON blockchain based on the source address, destination address.

The `tryLocateSourceTx` method attempts to locate the source transaction in the TON blockchain based on the source address, destination address, and the logical time of a result transaction. This method is useful for tracing back the origin of a transaction.

<Note>
  **TON billing: full (1 RU)**

  This method is always billed as full. See [Request units — TON method scope](/docs/request-units#ton-method-scope).
</Note>

## Parameters

* `source` (string, required) — The source address of the result transaction. Example: `UQAX2d4C2d48JeA-0y2_peGabRVumnKY22xPvkuEayC3zTI1`.
* `destination` (string, required) — The destination address of the result transaction. Example: `UQBP4mzpDIywL1SV-Wp9ZuBBlzprR9eXQgSYGEXiUEHm73vA`.
* `created_lt` (string, required) — The logical time when the result transaction was created. Example: `47597573000002`.

## JSON-RPC example

```shell Shell theme={"system"}
curl -X POST \
  'https://ton-mainnet.core.chainstack.com/f2a2411bce1e54a2658f2710cd7969c3/api/v2/jsonRPC' \
  -H 'Content-Type: application/json' \
  -d '{
    "jsonrpc": "2.0",
    "id": 1,
    "method": "tryLocateSourceTx",
    "params": {
      "source": "UQAX2d4C2d48JeA-0y2_peGabRVumnKY22xPvkuEayC3zTI1",
      "destination": "UQBP4mzpDIywL1SV-Wp9ZuBBlzprR9eXQgSYGEXiUEHm73vA",
      "created_lt": "47597573000002"
    }
  }'
```

## Response

* `block` (object) — Information about the block containing the source transaction:
  * `workchain` (integer) — The workchain ID of the block.
  * `shard` (string) — The shard ID of the block.
  * `seqno` (integer) — The sequence number of the block.
  * `root_hash` (string) — The root hash of the block.
  * `file_hash` (string) — The file hash of the block.
* `transaction_id` (object) — The identifier of the source transaction:
  * `lt` (string) — The logical time of the source transaction.
  * `hash` (string) — The hash of the source transaction.

## Use case

A possible use case for the `tryLocateSourceTx` method in TON is for applications or services that need to trace the origin of transactions. This method can be used to:

1. Implement transaction history tracing in blockchain explorers.
2. Analyze the chain of events leading to a specific transaction.
3. Verify the authenticity of a transaction by tracing it back to its source.
4. Debug smart contract interactions by identifying the initiating transaction.


## OpenAPI

````yaml openapi/ton_node_api/v2/tryLocateSourceTx.json GET /tryLocateSourceTx
openapi: 3.0.0
info:
  title: tryLocateSourceTx example
  version: 1.0.0
  description: >-
    This is an API example for tryLocateSourceTx, a method to locate the source
    transaction in the TON blockchain based on source, destination, and logical
    time of a result transaction.
servers:
  - url: >-
      https://ton-mainnet.core.chainstack.com/f2a2411bce1e54a2658f2710cd7969c3/api/v2
security: []
paths:
  /tryLocateSourceTx:
    get:
      tags:
        - TON Operations
      summary: tryLocateSourceTx
      operationId: tryLocateSourceTx
      parameters:
        - name: source
          in: query
          required: true
          description: The source address of the result transaction
          schema:
            type: string
            default: UQAX2d4C2d48JeA-0y2_peGabRVumnKY22xPvkuEayC3zTI1
          example: UQAX2d4C2d48JeA-0y2_peGabRVumnKY22xPvkuEayC3zTI1
        - name: destination
          in: query
          required: true
          description: The destination address of the result transaction
          schema:
            type: string
            default: UQBP4mzpDIywL1SV-Wp9ZuBBlzprR9eXQgSYGEXiUEHm73vA
          example: UQBP4mzpDIywL1SV-Wp9ZuBBlzprR9eXQgSYGEXiUEHm73vA
        - name: created_lt
          in: query
          required: true
          description: The logical time when the result transaction was created
          schema:
            type: string
            default: '47597573000002'
          example: '47597573000002'
      responses:
        '200':
          description: Information about the located source transaction
          content:
            application/json:
              schema:
                type: object
                properties:
                  block:
                    type: object
                    properties:
                      workchain:
                        type: integer
                        description: >-
                          The workchain ID of the block containing the source
                          transaction
                      shard:
                        type: string
                        description: >-
                          The shard ID of the block containing the source
                          transaction
                      seqno:
                        type: integer
                        description: >-
                          The sequence number of the block containing the source
                          transaction
                      root_hash:
                        type: string
                        description: >-
                          The root hash of the block containing the source
                          transaction
                      file_hash:
                        type: string
                        description: >-
                          The file hash of the block containing the source
                          transaction
                  transaction_id:
                    type: object
                    properties:
                      lt:
                        type: string
                        description: The logical time of the source transaction
                      hash:
                        type: string
                        description: The hash of the source transaction

````