Open the bank account (ACH) session
Resolves the bank account (ACH) payment account for the cart and returns
the ACH session: the provider the account runs on, the amount the debit
will ask for, and what that provider’s collector mounts with. The
checkout calls it when the shopper looks at bank account and mounts the
provider’s collector from the answer. No request body. It only reads: it
does not set the cart’s payment method, create a payment method, register
a webhook or void an open charge, so calling it again is safe and a
shopper who looks at bank account and goes back to another method is
unaffected. PUT payment_method with type ach records the choice when
the shopper pays. A cart that cannot pay by bank account is refused with
422 and meta.code = ach_points or ach_unavailable, the same codes
as that write. Cart-token authenticated. Returns 404 when the cart is not
found and 410 when the cart has already been processed or holds an
authorized enrollment.
curl --request POST \
--url https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-sessionimport requests
url = "https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session"
response = requests.post(url)
print(response.text)const options = {method: 'POST'};
fetch('https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"net/http"
"io"
)
func main() {
url := "https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session"
req, _ := http.NewRequest("POST", url, nil)
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.post("https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Post.new(url)
response = http.request(request)
puts response.read_body{
"ach": {
"provider": "stripe",
"amount_cents": 3999,
"currency": "usd",
"mandate_text": null,
"client": {
"publishable_key": "pk_test_51Abc"
}
},
"meta": {
"request_id": "018f2c1a-8b3a-7e6d-9f10-2a3b4c5d6e7f",
"timestamp": "2026-04-01T12:00:00Z"
}
}{
"error_message": "<string>",
"errors": "<string>",
"meta": {
"request_id": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}{
"error_message": "<string>",
"errors": "<string>",
"meta": {
"request_id": "<string>",
"timestamp": "2023-11-07T05:31:56Z",
"shop_url": "<string>",
"cart": {}
}
}{
"error_message": "<string>",
"errors": {
"payment_method": [
"<string>"
]
},
"meta": {
"request_id": "<string>",
"timestamp": "2023-11-07T05:31:56Z",
"code": "ach_points"
}
}Headers
Optional non-authorizing checkout journey UUID. Use with X-Checkout-Attempt-Id. Capture is disabled by default; malformed or incomplete pairs are ignored without changing checkout behavior. Cart scope comes from the authenticated cart token, never these headers.
Optional customer-submission UUID paired with X-Checkout-Journey-Id. Retain it for transport retries and originating continuations; use a new UUID for a new customer submission. It does not replace payment or order idempotency keys. Invalid pairs are ignored rather than rejecting payment.
Path Parameters
Opaque cart token returned by the create-cart response. It scopes the request to a single cart and is the credential for these endpoints — cart-token authentication carried in the path, with no bearer token or API key.
Response
The ACH session
Success body for the ACH session.
The ACH session. Routing has chosen the account behind it, and the checkout mounts that provider's collector from this object alone. The payment-method list carries no provider credentials.
Show child attributes
Show child attributes
Standard response metadata included on every response.
Show child attributes
Show child attributes
curl --request POST \
--url https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-sessionimport requests
url = "https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session"
response = requests.post(url)
print(response.text)const options = {method: 'POST'};
fetch('https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session', options)
.then(res => res.json())
.then(res => console.log(res))
.catch(err => console.error(err));<?php
$curl = curl_init();
curl_setopt_array($curl, [
CURLOPT_URL => "https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session",
CURLOPT_RETURNTRANSFER => true,
CURLOPT_ENCODING => "",
CURLOPT_MAXREDIRS => 10,
CURLOPT_TIMEOUT => 30,
CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
CURLOPT_CUSTOMREQUEST => "POST",
]);
$response = curl_exec($curl);
$err = curl_error($curl);
curl_close($curl);
if ($err) {
echo "cURL Error #:" . $err;
} else {
echo $response;
}package main
import (
"fmt"
"net/http"
"io"
)
func main() {
url := "https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session"
req, _ := http.NewRequest("POST", url, nil)
res, _ := http.DefaultClient.Do(req)
defer res.Body.Close()
body, _ := io.ReadAll(res.Body)
fmt.Println(string(body))
}HttpResponse<String> response = Unirest.post("https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session")
.asString();require 'uri'
require 'net/http'
url = URI("https://api.fluid.app/api/payments/v2026-04/carts/{cart_token}/ach-session")
http = Net::HTTP.new(url.host, url.port)
http.use_ssl = true
request = Net::HTTP::Post.new(url)
response = http.request(request)
puts response.read_body{
"ach": {
"provider": "stripe",
"amount_cents": 3999,
"currency": "usd",
"mandate_text": null,
"client": {
"publishable_key": "pk_test_51Abc"
}
},
"meta": {
"request_id": "018f2c1a-8b3a-7e6d-9f10-2a3b4c5d6e7f",
"timestamp": "2026-04-01T12:00:00Z"
}
}{
"error_message": "<string>",
"errors": "<string>",
"meta": {
"request_id": "<string>",
"timestamp": "2023-11-07T05:31:56Z"
}
}{
"error_message": "<string>",
"errors": "<string>",
"meta": {
"request_id": "<string>",
"timestamp": "2023-11-07T05:31:56Z",
"shop_url": "<string>",
"cart": {}
}
}{
"error_message": "<string>",
"errors": {
"payment_method": [
"<string>"
]
},
"meta": {
"request_id": "<string>",
"timestamp": "2023-11-07T05:31:56Z",
"code": "ach_points"
}
}