Start a new bank connection

curl --request POST \
  --url https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "institution_id": "<string>",
  "redirect_url": "<string>",
  "credentials": {}
}
'

import requests

url = "https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections"

payload = {
    "institution_id": "<string>",
    "redirect_url": "<string>",
    "credentials": {}
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({institution_id: '<string>', redirect_url: '<string>', credentials: {}})
};

fetch('https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections', 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-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'institution_id' => '<string>',
    'redirect_url' => '<string>',
    'credentials' => [
        
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections"

	payload := strings.NewReader("{\n  \"institution_id\": \"<string>\",\n  \"redirect_url\": \"<string>\",\n  \"credentials\": {}\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	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-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"institution_id\": \"<string>\",\n  \"redirect_url\": \"<string>\",\n  \"credentials\": {}\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"institution_id\": \"<string>\",\n  \"redirect_url\": \"<string>\",\n  \"credentials\": {}\n}"

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

{
  "operation_id": "op_01HXYZ8A6N7K2W9PQ4T5Z3V6E0",
  "status": "queued",
  "poll_url": "https://api-sandbox.ledgersyncappv2.com/v3/operations/op_01HXYZ8A6N7K2W9PQ4T5Z3V6E0",
  "estimated_seconds": 123
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

Connections

Start a new bank connection

Kick off a connection between a Client and a bank. Send only institution_id (a v3 catalog id from GET /v3/institutions). LedgerSync’s router picks the underlying source (Finicity vs MX) per its routing rules — integrators don’t pick a source.

The response:

Finicity / MX — we hand back a widget URL. Open it in the user’s browser (or your mobile webview) and they’ll finish linking. For MX the URL points at a LedgerSync-hosted wrapper page (GET /connections/mx-wrapper) that embeds the MX widget and gives you the same redirect_url + ls_token completion hop as Finicity (verify it at POST /connections/redirect-token/verify).
FDE — we return a widget_url to a LedgerSync-hosted connect page where the end user enters their bank credentials and answers any security questions in-session. Raw credentials are never sent to the API.

This one’s genuinely async — the bank or document pipeline takes a few seconds to a minute. You get 202 Accepted and an operation_id right away; the connection.active (or connection.requires_action / connection.failed) webhook fires when it’s done. Poll GET /operations/{operation_id} if you can’t run a webhook handler.

Note on connection.id. While this operation is queued/running, the embedded result.connection.id is a UUID-prefixed placeholder (con_<uuid>) and cannot be used with any other endpoint. The canonical id — con_<SOURCE>_<bankAccountId> such as con_FINICITY_41294 or con_MX_1224 — is only assigned once the user finishes the widget and the source pushes its first callback. Read the canonical id from GET /operations/{operation_id} once status=succeeded, or from the connection.active webhook. See the Connection lifecycle section at the top of this reference for the full handshake.

POST

clients

{client_id}

connections

Start a new bank connection

curl --request POST \
  --url https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "institution_id": "<string>",
  "redirect_url": "<string>",
  "credentials": {}
}
'

import requests

url = "https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections"

payload = {
    "institution_id": "<string>",
    "redirect_url": "<string>",
    "credentials": {}
}
headers = {
    "Authorization": "Bearer <token>",
    "Content-Type": "application/json"
}

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

print(response.text)

const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: JSON.stringify({institution_id: '<string>', redirect_url: '<string>', credentials: {}})
};

fetch('https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections', 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-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections",
  CURLOPT_RETURNTRANSFER => true,
  CURLOPT_ENCODING => "",
  CURLOPT_MAXREDIRS => 10,
  CURLOPT_TIMEOUT => 30,
  CURLOPT_HTTP_VERSION => CURL_HTTP_VERSION_1_1,
  CURLOPT_CUSTOMREQUEST => "POST",
  CURLOPT_POSTFIELDS => json_encode([
    'institution_id' => '<string>',
    'redirect_url' => '<string>',
    'credentials' => [
        
    ]
  ]),
  CURLOPT_HTTPHEADER => [
    "Authorization: Bearer <token>",
    "Content-Type: application/json"
  ],
]);

$response = curl_exec($curl);
$err = curl_error($curl);

curl_close($curl);

if ($err) {
  echo "cURL Error #:" . $err;
} else {
  echo $response;
}

package main

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

func main() {

	url := "https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections"

	payload := strings.NewReader("{\n  \"institution_id\": \"<string>\",\n  \"redirect_url\": \"<string>\",\n  \"credentials\": {}\n}")

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

	req.Header.Add("Authorization", "Bearer <token>")
	req.Header.Add("Content-Type", "application/json")

	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-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections")
  .header("Authorization", "Bearer <token>")
  .header("Content-Type", "application/json")
  .body("{\n  \"institution_id\": \"<string>\",\n  \"redirect_url\": \"<string>\",\n  \"credentials\": {}\n}")
  .asString();

require 'uri'
require 'net/http'

url = URI("https://api-sandbox.ledgersyncappv2.com/v3/clients/{client_id}/connections")

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

request = Net::HTTP::Post.new(url)
request["Authorization"] = 'Bearer <token>'
request["Content-Type"] = 'application/json'
request.body = "{\n  \"institution_id\": \"<string>\",\n  \"redirect_url\": \"<string>\",\n  \"credentials\": {}\n}"

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

{
  "operation_id": "op_01HXYZ8A6N7K2W9PQ4T5Z3V6E0",
  "status": "queued",
  "poll_url": "https://api-sandbox.ledgersyncappv2.com/v3/operations/op_01HXYZ8A6N7K2W9PQ4T5Z3V6E0",
  "estimated_seconds": 123
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

{
  "error": {
    "code": "unknown_api_key",
    "message": "The API key you presented doesn't match any active key.",
    "type": "auth_error",
    "doc_url": "https://portal.ledgersyncappv2.com/errors/unknown_api_key",
    "category": "AUTH_ERROR",
    "is_user_actionable": true,
    "source_diagnostic_code": "FIN-103",
    "param": "client.email",
    "trace_id": "4bf92f3577b34da6a3ce929d0e0e4736",
    "errors": [
      {
        "param": "client.email",
        "message": "must be a valid email address",
        "code": "invalid_email"
      }
    ]
  }
}

Authorizations

Authorization

string

header

required

Pass your secret key in the Authorization header as a Bearer token: Authorization: Bearer sk_test_... (sandbox) or Bearer sk_live_... (production).

Keys are created in the developer portal and the plaintext secret is shown exactly once at creation. Treat them like passwords — never embed them in mobile apps or front-end code.

Headers

Idempotency-Key

string

Safe-retry key for POSTs. Send any unique string per logical request (a UUIDv4 is great). If the network drops and you retry with the same Idempotency-Key within 24 hours, you get the exact same response back instead of creating a duplicate.

Cached responses include failures (4xx and 5xx) too. If a call failed because of a bad input and you want to try again with the corrected input, use a fresh key — otherwise you'll keep getting the cached failure.

Maximum string length: 255

Example:

"6f1a8c50-3e9c-4d4a-b1f5-2c5b9a2f7d11"

Path Parameters

client_id

string

required

Body

application/json

Source-hiding initiate-connection shape. The integrator passes only institution_id (a v3 catalog id from GET /v3/institutions); LedgerSync's router picks the underlying source. No source field.

institution_id

string

required

A v3 catalog id (e.g., ins_01HZX9CHASE) from GET /v3/institutions.

redirect_url

string<uri> | null

URL the widget redirects to on completion.

credentials

object | null

deprecated

Ignored. FDE connects via a LedgerSync-hosted page, so raw bank credentials are never accepted over the API. Retained only so a body that still carries it is not rejected.

Response

The request was accepted but the underlying work runs asynchronously. Use the returned operation_id to poll GET /operations/{operation_id} or just wait for the matching webhook event.

Returned with 202 Accepted for async operations.

operation_id

string

required

Example:

"op_01HXYZ8A6N7K2W9PQ4T5Z3V6E0"

status

enum<string>

required

Available options:

queued

poll_url

string<uri>

required

Example:

"https://api-sandbox.ledgersyncappv2.com/v3/operations/op_01HXYZ8A6N7K2W9PQ4T5Z3V6E0"

estimated_seconds

integer

Rough ETA for completion. Best-effort.

Health

Clients

Connections

Settings

Institutions

Accounts

Transactions

Statements

Checks

Operations

Webhooks

ApiKeys

Sandbox

Metrics

PortalGating

Start a new bank connection

Authorizations

Headers

Path Parameters

Body

Response