> For clean Markdown of any page, append .md to the page URL.
> For a complete documentation index, see https://docs.crisscross.money/api-reference/collect/payments/payment-initiation/initiate-transaction/llms.txt.
> For AI client integration (Claude Code, Cursor, etc.), connect to the MCP server at https://docs.crisscross.money/_mcp/server.

# Initiate Payment (Transaction)

POST https://api.crisscross.money/v1/payment
Content-Type: application/json

Initiates a payment transaction for an existing checkout session.
PayOS models a "payment" as a transaction; the primary identifier is `transactionId`.


Reference: https://docs.crisscross.money/api-reference/collect/payments/payment-initiation/initiate-transaction

## Request

### Body (application/json)

This endpoint expects an InitiateTransactionRequest.

- `paymentMethodId` (enum, required) — Payment method identifier.
  - Allowed values: `card`, `directcharge`, `mobilemoney`, `ieft`, `banktransfer`, `capitecpay`, `cardpresent`, `digitalwallet`, `bnpl`
- `sessionId` (string, required) — Unique identifier for the session.
- `paymentDetails` (PaymentDetails, required)
- `signature` (string, optional) — Optional signature used for hosted checkout verification.
- `attributes` (map from string to string, optional) — Optional transaction attributes.

## Response

### 201

Transaction initiated successfully.

- `transactionId` (string, required) — Unique identifier for the transaction.
- `status` (string, required) — Current transaction status.
- `message` (string, required) — Human-readable status message.
- `authState` (AuthState, optional) — Detail for the transaction's current state. When the transaction status is `AUTH_REQUIRED`, `authMethodType` says how the payer completes authentication, and a matching detail object (`redirect`, `fields`, `ussd`, `bankTransfer`) carries the specifics. Error states instead carry `code`, `message`, and the raw `connectorFailureCode`/`connectorFailureMessage`.

## Errors

### 400 Bad Request Error

Invalid request parameters.

- `message` (string, required) — Human-readable description of what went wrong.
- `error` (string, required) — Error category. Most endpoints return the HTTP reason phrase (e.g. "Bad Request", "Unauthorized", "Conflict", "Unprocessable Entity", "Internal Server Error"). Some return a machine-readable snake_case code instead — notably the FX and rate-lock rejections on checkout session creation and payment initiation, where several distinct codes share a single HTTP status. Where a code is present it is the finer discriminator and is safe to branch on.
- `statusCode` (integer, required) — HTTP status code, mirroring the response header. The response header is the source of truth.

### 401 Unauthorized Error

Unauthorized.

- `message` (string, required) — Human-readable description of what went wrong.
- `error` (string, required) — Error category. Most endpoints return the HTTP reason phrase (e.g. "Bad Request", "Unauthorized", "Conflict", "Unprocessable Entity", "Internal Server Error"). Some return a machine-readable snake_case code instead — notably the FX and rate-lock rejections on checkout session creation and payment initiation, where several distinct codes share a single HTTP status. Where a code is present it is the finer discriminator and is safe to branch on.
- `statusCode` (integer, required) — HTTP status code, mirroring the response header. The response header is the source of truth.

### 422 Unprocessable Entity Error

Unprocessable Entity. If the session carries a rate lock, the lock is re-verified here: one that is unknown, expired, or cancelled is rejected and a new lock must be fetched. Currency mismatches are not checked at this step. A lock's currencies are validated once, when it is attached at session creation, so only the two rejections below can occur here. Both share `422` — branch on `error`.

- `message` (string, required) — Human-readable description of what went wrong.
- `error` (string, required) — Error category. Most endpoints return the HTTP reason phrase (e.g. "Bad Request", "Unauthorized", "Conflict", "Unprocessable Entity", "Internal Server Error"). Some return a machine-readable snake_case code instead — notably the FX and rate-lock rejections on checkout session creation and payment initiation, where several distinct codes share a single HTTP status. Where a code is present it is the finer discriminator and is safe to branch on.
- `statusCode` (integer, required) — HTTP status code, mirroring the response header. The response header is the source of truth.

### 502 Bad Gateway Error

The rate-lock service could not be reached. Transient — retry with backoff. This is an upstream failure, not a problem with your request or your lock.

- `message` (string, required) — Human-readable description of what went wrong.
- `error` (string, required) — Error category. Most endpoints return the HTTP reason phrase (e.g. "Bad Request", "Unauthorized", "Conflict", "Unprocessable Entity", "Internal Server Error"). Some return a machine-readable snake_case code instead — notably the FX and rate-lock rejections on checkout session creation and payment initiation, where several distinct codes share a single HTTP status. Where a code is present it is the finer discriminator and is safe to branch on.
- `statusCode` (integer, required) — HTTP status code, mirroring the response header. The response header is the source of truth.

## Types

### PaymentDetails

- `type`: `card` (card)
  - `cardExpiryMonth` (string, required) — Expiry month (MM).
  - `cardExpiryYear` (string, required) — Expiry year (YYYY).
  - `cardHolderName` (string, required)
  - `encryptedCardCvv` (string, required) — Encrypted CVV token.
  - `encryptedCardNumber` (string, required) — Encrypted card number token.
  - `payerEmail` (string, required)
- `type`: `mobilemoney` (mobilemoney)
  - `payerMobileNumber` (string, required) — Payer mobile number.
  - `provider` (string, required) — Mobile money provider (varies by country).
  - `payerFullName` (string, optional) — Full name of the payer. Falls back to the checkout session payer name when omitted.
- `type`: `digitalwallet` (digitalwallet)
  - `deviceFingerprint` (string, required) — Base64-encoded device fingerprint from the wallets SDK, used for fraud screening. Omitting it will cause the payment to be rejected.
  - `encryptedWalletToken` (string, required) — Base64-encoded, single-use payment token released by the wallet. Short-lived and not reusable: a retry after a decline requires a new token from a new wallet interaction. Do not log it, and do not transform it.
  - `payerEmail` (string, required)
  - `provider` (enum, required) — The wallet that produced the token.
    - Allowed values: `apple-pay`, `google-pay`
- `type`: `bnpl` (bnpl)
  - `payerEmail` (string, required) — Identifies the customer within the instalment flow.
  - `payerMobileNumber` (string, optional) — Optional. Speeds up the instalment flow when supplied.
- `type`: `directcharge` (directcharge)
- `type`: `ieft` (ieft)
- `type`: `banktransfer` (banktransfer)
- `type`: `capitecpay` (capitecpay)
- `type`: `cardpresent` (cardpresent)

### AuthState

Detail for the transaction's current state. When the transaction status is `AUTH_REQUIRED`, `authMethodType` says how the payer completes authentication, and a matching detail object (`redirect`, `fields`, `ussd`, `bankTransfer`) carries the specifics. Error states instead carry `code`, `message`, and the raw `connectorFailureCode`/`connectorFailureMessage`.

- `state` (string, optional) — Transaction state name. In-flight states are uppercase (`PENDING`, `SCREENING_PENDING`, `SCREENING_COMPLETED`, `AUTH_REQUIRED`); terminal states are lowercase (`completed`, `failed`, `error`, `cancelled`, `expired`, `settled`). Match exact values, casing included.
- `transitionedAt` (string, optional) — ISO 8601 timestamp when the transaction entered this state.
- `authMethodType` (enum, optional) — How the payer completes authentication. Present on `AUTH_REQUIRED` states.
  - Allowed values: `redirect`, `fields`, `ussd`, `pendingApproval`, `bankTransfer`, `none`
- `redirect` (AuthStateRedirect, optional) — Present when `authMethodType` is `redirect` — send the payer to `url`.

### AuthStateRedirect

Present when `authMethodType` is `redirect` — send the payer to `url`.

- `url` (string, optional) — URL to redirect the payer to for authentication.
- `requiresTopLevel` (boolean, optional) — When true, the browser must navigate top-level to `url` rather than embedding it in an iframe.

## Examples

**Request**

```json
{
  "paymentMethodId": "card",
  "sessionId": "0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a",
  "paymentDetails": {
    "type": "card",
    "cardExpiryMonth": "12",
    "cardExpiryYear": "2028",
    "cardHolderName": "Chinwe Okafor",
    "encryptedCardCvv": "ev-cvv-token",
    "encryptedCardNumber": "ev-token",
    "payerEmail": "chinwe.okafor@example.com"
  }
}
```

**Response**

```json
{
  "transactionId": "9f3e4b2c-1a6d-4e88-9d3a-ff1234567890",
  "status": "AUTH_REQUIRED",
  "message": "Authorization required",
  "authState": {
    "state": "AUTH_REQUIRED",
    "transitionedAt": "2026-06-02T10:30:14Z",
    "authMethodType": "redirect",
    "redirect": {
      "url": "https://example.com/redirect"
    }
  }
}
```

**SDK Code**

```python
import requests

url = "https://api.crisscross.money/v1/payment"

payload = {
    "paymentMethodId": "card",
    "sessionId": "0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a",
    "paymentDetails": {
        "type": "card",
        "cardExpiryMonth": "12",
        "cardExpiryYear": "2028",
        "cardHolderName": "Chinwe Okafor",
        "encryptedCardCvv": "ev-cvv-token",
        "encryptedCardNumber": "ev-token",
        "payerEmail": "chinwe.okafor@example.com"
    }
}
headers = {"Content-Type": "application/json"}

response = requests.post(url, json=payload, headers=headers)

print(response.json())
```

```javascript
const url = 'https://api.crisscross.money/v1/payment';
const options = {
  method: 'POST',
  headers: {'Content-Type': 'application/json'},
  body: '{"paymentMethodId":"card","sessionId":"0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a","paymentDetails":{"type":"card","cardExpiryMonth":"12","cardExpiryYear":"2028","cardHolderName":"Chinwe Okafor","encryptedCardCvv":"ev-cvv-token","encryptedCardNumber":"ev-token","payerEmail":"chinwe.okafor@example.com"}}'
};

try {
  const response = await fetch(url, options);
  const data = await response.json();
  console.log(data);
} catch (error) {
  console.error(error);
}
```

```go
package main

import (
	"fmt"
	"strings"
	"net/http"
	"io"
)

func main() {

	url := "https://api.crisscross.money/v1/payment"

	payload := strings.NewReader("{\n  \"paymentMethodId\": \"card\",\n  \"sessionId\": \"0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a\",\n  \"paymentDetails\": {\n    \"type\": \"card\",\n    \"cardExpiryMonth\": \"12\",\n    \"cardExpiryYear\": \"2028\",\n    \"cardHolderName\": \"Chinwe Okafor\",\n    \"encryptedCardCvv\": \"ev-cvv-token\",\n    \"encryptedCardNumber\": \"ev-token\",\n    \"payerEmail\": \"chinwe.okafor@example.com\"\n  }\n}")

	req, _ := http.NewRequest("POST", url, payload)

	req.Header.Add("Content-Type", "application/json")

	res, _ := http.DefaultClient.Do(req)

	defer res.Body.Close()
	body, _ := io.ReadAll(res.Body)

	fmt.Println(res)
	fmt.Println(string(body))

}
```

```ruby
require 'uri'
require 'net/http'

url = URI("https://api.crisscross.money/v1/payment")

http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true

request = Net::HTTP::Post.new(url)
request["Content-Type"] = 'application/json'
request.body = "{\n  \"paymentMethodId\": \"card\",\n  \"sessionId\": \"0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a\",\n  \"paymentDetails\": {\n    \"type\": \"card\",\n    \"cardExpiryMonth\": \"12\",\n    \"cardExpiryYear\": \"2028\",\n    \"cardHolderName\": \"Chinwe Okafor\",\n    \"encryptedCardCvv\": \"ev-cvv-token\",\n    \"encryptedCardNumber\": \"ev-token\",\n    \"payerEmail\": \"chinwe.okafor@example.com\"\n  }\n}"

response = http.request(request)
puts response.read_body
```

```java
import com.mashape.unirest.http.HttpResponse;
import com.mashape.unirest.http.Unirest;

HttpResponse<String> response = Unirest.post("https://api.crisscross.money/v1/payment")
  .header("Content-Type", "application/json")
  .body("{\n  \"paymentMethodId\": \"card\",\n  \"sessionId\": \"0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a\",\n  \"paymentDetails\": {\n    \"type\": \"card\",\n    \"cardExpiryMonth\": \"12\",\n    \"cardExpiryYear\": \"2028\",\n    \"cardHolderName\": \"Chinwe Okafor\",\n    \"encryptedCardCvv\": \"ev-cvv-token\",\n    \"encryptedCardNumber\": \"ev-token\",\n    \"payerEmail\": \"chinwe.okafor@example.com\"\n  }\n}")
  .asString();
```

```php
<?php
require_once('vendor/autoload.php');

$client = new \GuzzleHttp\Client();

$response = $client->request('POST', 'https://api.crisscross.money/v1/payment', [
  'body' => '{
  "paymentMethodId": "card",
  "sessionId": "0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a",
  "paymentDetails": {
    "type": "card",
    "cardExpiryMonth": "12",
    "cardExpiryYear": "2028",
    "cardHolderName": "Chinwe Okafor",
    "encryptedCardCvv": "ev-cvv-token",
    "encryptedCardNumber": "ev-token",
    "payerEmail": "chinwe.okafor@example.com"
  }
}',
  'headers' => [
    'Content-Type' => 'application/json',
  ],
]);

echo $response->getBody();
```

```csharp
using RestSharp;

var client = new RestClient("https://api.crisscross.money/v1/payment");
var request = new RestRequest(Method.POST);
request.AddHeader("Content-Type", "application/json");
request.AddParameter("application/json", "{\n  \"paymentMethodId\": \"card\",\n  \"sessionId\": \"0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a\",\n  \"paymentDetails\": {\n    \"type\": \"card\",\n    \"cardExpiryMonth\": \"12\",\n    \"cardExpiryYear\": \"2028\",\n    \"cardHolderName\": \"Chinwe Okafor\",\n    \"encryptedCardCvv\": \"ev-cvv-token\",\n    \"encryptedCardNumber\": \"ev-token\",\n    \"payerEmail\": \"chinwe.okafor@example.com\"\n  }\n}", ParameterType.RequestBody);
IRestResponse response = client.Execute(request);
```

```swift
import Foundation

let headers = ["Content-Type": "application/json"]
let parameters = [
  "paymentMethodId": "card",
  "sessionId": "0d3f1d6c-1c49-4b89-9db6-1fdc06f24c8a",
  "paymentDetails": [
    "type": "card",
    "cardExpiryMonth": "12",
    "cardExpiryYear": "2028",
    "cardHolderName": "Chinwe Okafor",
    "encryptedCardCvv": "ev-cvv-token",
    "encryptedCardNumber": "ev-token",
    "payerEmail": "chinwe.okafor@example.com"
  ]
] as [String : Any]

let postData = JSONSerialization.data(withJSONObject: parameters, options: [])

let request = NSMutableURLRequest(url: NSURL(string: "https://api.crisscross.money/v1/payment")! as URL,
                                        cachePolicy: .useProtocolCachePolicy,
                                    timeoutInterval: 10.0)
request.httpMethod = "POST"
request.allHTTPHeaderFields = headers
request.httpBody = postData as Data

let session = URLSession.shared
let dataTask = session.dataTask(with: request as URLRequest, completionHandler: { (data, response, error) -> Void in
  if (error != nil) {
    print(error as Any)
  } else {
    let httpResponse = response as? HTTPURLResponse
    print(httpResponse)
  }
})

dataTask.resume()
```