Flint Books APIDeveloper Reference

Flint Books REST API

Push and pull accounting data from external systems. Authenticate with a per-company API key, then send standard HTTP requests to the function endpoint.

Authentication

Every request must include an x-api-key header. Generate a key from Settings → API Access inside your Flint Books account. The key is scoped to a single company — it can only read and modify that company's records.

curl -H "x-api-key: <YOUR_API_KEY>" "<YOUR_FUNCTION_URL>?resource=transactions"

Endpoint

All requests go to a single endpoint — the deployed URL of the ledgerflowApi backend function. Find it under Dashboard → Code → Functions → ledgerflowApi. The desired resource is selected via a resource query param (GET / DELETE) or in the JSON body (POST / PUT).

POST / GET / PUT / DELETE <YOUR_FUNCTION_URL>

Resources

transactionsTransaction

Bank feed and manual ledger entries

invoicesInvoice

Sales and purchase invoices

clientsClient

Customer / client contacts

suppliersSupplier

Supplier contacts

expensesExpense

Employee-submitted expenses

vat_returnsVatReturn

Period VAT returns

bank_accountsBankAccount

Connected and manual bank accounts

Operations

Method	Purpose	Where to specify
GET	List records or get one by `id`	?resource=&id=&limit=&cursor=&filters
POST	Create a new record	body: { resource, data }
PUT	Update an existing record	body: { resource, id, data }
DELETE	Delete a record	?resource=&id=

Pagination

List responses return up to limit records (max 500) and a cursor:

{
  "data": [ /* records */ ],
  "count": 50,
  "has_more": true,
  "next_cursor": "REC_ID_STR"
}

When has_more is true, request the next page by addingcursor=<next_cursor> to the URL.

Examples

List with filters

# List transactions (with pagination)
curl -H "x-api-key: <YOUR_API_KEY>" \
  "<YOUR_FUNCTION_URL>?resource=transactions&limit=50"

# Filter by status / type
curl -H "x-api-key: <YOUR_API_KEY>" \
  "<YOUR_FUNCTION_URL>?resource=transactions&status=uncategorised&transaction_type=debit"

Get a single record

# Get a single transaction
curl -H "x-api-key: <YOUR_API_KEY>" \
  "<YOUR_FUNCTION_URL>?resource=transactions&id=<ID>"

Create

# Create a transaction
curl -X POST -H "x-api-key: <YOUR_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "resource": "transactions",
    "data": {
      "date": "2026-07-29",
      "description": "Office supplies",
      "amount_pence": 5000,
      "transaction_type": "debit",
      "status": "uncategorised"
    }
  }' \
  "<YOUR_FUNCTION_URL>"

Update

# Update an invoice to paid
curl -X PUT -H "x-api-key: <YOUR_API_KEY>" \
  -H "Content-Type: application/json" \
  -d '{
    "resource": "invoices",
    "id": "<INVOICE_ID>",
    "data": { "status": "paid" }
  }' \
  "<YOUR_FUNCTION_URL>"

Delete

# Delete a client
curl -X DELETE -H "x-api-key: <YOUR_API_KEY>" \
  "<YOUR_FUNCTION_URL>?resource=clients&id=<CLIENT_ID>"

Pagination

# Pagination — pass next_cursor to fetch the next page
curl -H "x-api-key: <YOUR_API_KEY>" \
  "<YOUR_FUNCTION_URL>?resource=transactions&limit=100&cursor=<next_cursor>"

Errors

Status	Meaning
400	Malformed body or missing resource
401	Missing or invalid API key
404	Record not found, or belongs to another company
405	Method not allowed
500	Internal error

Flint Books API · provided by Flint Digital