# Look up a transfer with the bank

Source: https://checkslip.com/en/docs/lookup-slip

POST `https://api.checkslip.com/api/slips/lookup`

API key

Send the QR text read from the slip, or the slip image, and we ask the sending bank for the transfer it holds and return that data. We return what the bank has; the decision to accept the payment is yours, against your own order. The result is in outcome, e.g. FOUND, NOT_FOUND, DUPLICATE, PENDING. One credit is used only when outcome is FOUND. We never store the slip image, only the QR text. Images up to 10 MB and 50 megapixels, JPEG, PNG or WebP only (HEIC, GIF and PDF get 422 invalid-file, no credit). Always send an Idempotency-Key; a retry with the same value returns the same result and never charges twice. Needs an API key with slip:lookup.

## Parameters

| Field | In | Type | Required |
| --- | --- | --- | --- |
| `Idempotency-Key` | header | `string` | no |

## Request body

`application/json` Also accepts: `multipart/form-data`

| Field | Type | Required |
| --- | --- | --- |
| `qr` | `string` | yes |
| `client_reference` | `string \| null` | no |

## Responses

### 200 `application/json`

| Field | Type | Required |
| --- | --- | --- |
| `request_id` | `string (uuid)` | yes |
| `outcome` | `FOUND \| NOT_FOUND \| DUPLICATE \| PENDING` | yes |
| `checked_at` | `string (date-time)` | yes |
| `slip` | `Slip \| SlipSummary` | yes |
| `duplicate_of` | `DuplicateOf` | no |
| `duplicate_of.request_id` | `string (uuid)` | yes |
| `duplicate_of.checked_at` | `string (date-time)` | yes |
| `client_reference` | `string \| null` | no |

### 202 `application/json`

| Field | Type | Required |
| --- | --- | --- |
| `request_id` | `string (uuid)` | yes |
| `outcome` | `FOUND \| NOT_FOUND \| DUPLICATE \| PENDING` | yes |
| `checked_at` | `string (date-time)` | yes |
| `slip` | `Slip \| SlipSummary` | yes |
| `duplicate_of` | `DuplicateOf` | no |
| `duplicate_of.request_id` | `string (uuid)` | yes |
| `duplicate_of.checked_at` | `string (date-time)` | yes |
| `client_reference` | `string \| null` | no |

### Possible errors

400 401 402 403 409 413 415 422 429 500 503

An error as Problem Details. All codes are listed at [Error codes](https://checkslip.com/en/docs/errors)

**cURL**

```bash
curl https://api.checkslip.com/api/slips/lookup \
  -H "Authorization: Bearer $CHECKSLIP_API_KEY" \
  -H "Idempotency-Key: order-1042-slip-1" \
  -H "Content-Type: application/json" \
  -d '{"qr":"00330006000001010306902126302105340875102TH9104F86F"}'
```

**Node.js**

```javascript
const res = await fetch("https://api.checkslip.com/api/slips/lookup", {
  method: "POST",
  headers: {
    Authorization: `Bearer ${process.env.CHECKSLIP_API_KEY}`,
    "Idempotency-Key": "order-1042-slip-1",
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    qr: "00330006000001010306902126302105340875102TH9104F86F",
  }),
});
const data = await res.json();
```

**Python**

```python
import os

import requests

res = requests.post(
    "https://api.checkslip.com/api/slips/lookup",
    headers={
        "Authorization": f"Bearer {os.environ['CHECKSLIP_API_KEY']}",
        "Idempotency-Key": "order-1042-slip-1",
    },
    json={
        "qr": "00330006000001010306902126302105340875102TH9104F86F",
    },
)
data = res.json()
```

**200 found**

```json
{
  "request_id": "0192d4e0-7c1a-7b3e-9f00-1a2b3c4d5e6f",
  "outcome": "FOUND",
  "checked_at": "2026-10-29T10:41:02+07:00",
  "slip": {
    "trans_ref": "630210534087",
    "transferred_at": "2026-10-29T10:33:30+07:00",
    "amount": {
      "satang": 5000,
      "currency": "THB"
    },
    "sender": {
      "bank": {
        "code": "KKP",
        "bot_code": "069",
        "name_th": "ธนาคารเกียรตินาคินภัทร",
        "name_en": "Kiatnakin Phatra Bank"
      },
      "name_th": "นาย สมชาย ใ",
      "name_en": "MR. SOMCHAI J",
      "account": "0439"
    },
    "receiver": {
      "kind": "BANK_ACCOUNT",
      "bank": {
        "code": "GSB",
        "bot_code": "030",
        "name_th": "ธนาคารออมสิน",
        "name_en": "Government Savings Bank"
      },
      "name_th": "นางสาว สมหญิง ร",
      "name_en": "MISS SOMYING R",
      "account": "9681"
    }
  }
}
```

**200 found_bill_payment**

```json
{
  "request_id": "0192d4e0-7c1a-7b3e-9f00-1a2b3c4d5e70",
  "outcome": "FOUND",
  "checked_at": "2026-10-29T10:41:02+07:00",
  "slip": {
    "trans_ref": "630210534088",
    "transferred_at": "2026-10-29T10:33:30+07:00",
    "amount": {
      "satang": 125050,
      "currency": "THB"
    },
    "sender": {
      "bank": {
        "code": "KKP",
        "bot_code": "069",
        "name_th": "ธนาคารเกียรตินาคินภัทร",
        "name_en": "Kiatnakin Phatra Bank"
      },
      "name_th": "นาย สมชาย ใ",
      "name_en": "MR. SOMCHAI J",
      "account": "0439"
    },
    "receiver": {
      "kind": "BILL_PAYMENT",
      "bank": null,
      "name_th": "บริษัท ตัวอย่าง จำกัด",
      "name_en": null,
      "account": null
    }
  }
}
```

**200 duplicate**

```json
{
  "request_id": "0192d4e2-1111-7c00-8000-000000000002",
  "outcome": "DUPLICATE",
  "checked_at": "2026-10-29T10:45:10+07:00",
  "slip": {
    "trans_ref": "630210534087",
    "sender_bank": {
      "code": "KKP",
      "bot_code": "069",
      "name_th": "ธนาคารเกียรตินาคินภัทร",
      "name_en": "Kiatnakin Phatra Bank"
    },
    "receiver_bank": {
      "code": "GSB",
      "bot_code": "030",
      "name_th": "ธนาคารออมสิน",
      "name_en": "Government Savings Bank"
    },
    "transferred_at": "2026-10-29T10:33:30+07:00",
    "amount": {
      "satang": 5000,
      "currency": "THB"
    }
  },
  "duplicate_of": {
    "request_id": "0192d4e0-7c1a-7b3e-9f00-1a2b3c4d5e6f",
    "checked_at": "2026-10-29T10:41:02+07:00"
  }
}
```

**202**

```json
{
  "request_id": "0b6c2f5e-8a41-4d1e-9c3a-5f7e2d18a6b4",
  "outcome": "FOUND",
  "checked_at": "2026-11-05T09:30:00+07:00",
  "slip": {
    "trans_ref": "630210534087",
    "transferred_at": "2026-10-29T10:33:30+07:00",
    "amount": {
      "satang": 5000,
      "currency": "THB"
    },
    "sender": {
      "bank": {
        "code": "KKP",
        "bot_code": "069",
        "name_th": "ธนาคารเกียรตินาคินภัทร",
        "name_en": "Kiatnakin Phatra Bank"
      },
      "name_th": "นาย สมชาย ใ",
      "name_en": "MR. SOMCHAI J",
      "account": "0439"
    },
    "receiver": {
      "kind": "BANK_ACCOUNT",
      "bank": {
        "code": "KKP",
        "bot_code": "069",
        "name_th": "ธนาคารเกียรตินาคินภัทร",
        "name_en": "Kiatnakin Phatra Bank"
      },
      "name_th": "ร้าน ทดสอบ",
      "name_en": "TEST S",
      "account": "0439"
    },
    "names_erased": true
  },
  "duplicate_of": {
    "request_id": "0b6c2f5e-8a41-4d1e-9c3a-5f7e2d18a6b4",
    "checked_at": "2026-11-05T09:30:00+07:00"
  },
  "client_reference": "ORDER-10023"
}
```