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REST API

Invoicing API for your own software

The Invoice Office invoicing API is a REST API that connects your webshop, CRM or ERP to your invoicing. Create invoices, quotes and credit notes, keep customers and products in sync, and log CRM activities — all over HTTPS in JSON, with an open, documented API reference.

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Docs open to everyone · API included in the Pro license · Free trial

The Invoice Office API documentation open on the Create an invoice endpoint, with the request body fields such as customerId, lines and status, a curl example sending the X-AUTH-TOKEN header, and the sidebar of invoice, order confirmation and packing note endpoints

What you can connect

What the invoicing API covers

The API works on the same records you see in the app — so a document created through the API is an ordinary invoice, quote or packing note in your account.

Documented API
REST + OpenAPI 3.1Documented API
Response formats
JSON, XML, CSVResponse formats
Authentication
API key or JWTAuthentication
Invoices and sales documents
A REST API for invoices and sales documents: list, create, update and delete invoices, quotes, order confirmations, credit notes, proforma invoices and packing notes. Recurring invoices and payment reminders can be read.
Customers and suppliers
Keep your customer and supplier records in sync with your CRM, webshop or ERP: create, update and delete accounts, and read their contact persons.
Products, stock and price lists
Create and update products, and read stock levels, stock mutations, price lists, product suppliers, dimensions and specifications.
Purchases and purchase orders
Push supplier costs in as purchases, create purchase orders, and read your recurring purchases.
CRM activities
Log calls, e-mails, meetings, notes, SMS, WhatsApp and LinkedIn messages against your customers, so every contact moment lands in one place.
Convert one document into another
Works like creating one document from another in the app: turn a quote into an order confirmation or invoice, an invoice into a packing note or credit note. Lines, customer and addresses are copied over.

API documentation

Read the API documentation before you sign up

The API reference is public — no account needed. Your developer can check every endpoint, field and response before you decide, and come back to the same page while building.

Open the Invoice Office API reference

  • Open, interactive API reference

    Every endpoint is documented with its parameters, request body and response schema. Search the reference, open the API client, or download the OpenAPI document to generate a client in your own language.

  • Two ways to authenticate

    Send your API secret in the X-AUTH-TOKEN header on each request, or exchange an e-mail address and password for a JWT at the Login Check endpoint and send it as a Bearer token.

  • The formats your system speaks

    Responses come as JSON, JSON-LD, XML, CSV or YAML. Updates use JSON merge patch, so you only send the fields that change.

  • Filter and page through results

    List endpoints are paginated with the _page parameter. Invoices can be filtered by document number and by document, delivery, payment or creation date ranges.

Integrations

What teams build with the API

Invoice orders from your webshop
Create the customer if they are new, then create the invoice with its lines — set createProducts and missing products are created for you as it goes.
Sync your CRM
Keep customers in one system of record and push changes to Invoice Office, with calls, meetings and notes logged as CRM activities.
Feed your own dashboards
Pull invoices, purchases and stock into a data warehouse, spreadsheet or BI tool on your own schedule, in JSON or CSV.
Automate the paperwork
When an order ships, convert its order confirmation into a packing note and an invoice from your own system — no copying between screens.

Getting started

Your first API call in three steps

  1. Step 1:Switch on the Pro license

    The REST API is part of the Pro license. Start a free trial, or buy Pro under Settings › Licenses.

  2. Step 2:Create your API key and secret

    Go to Settings › Security center › API key and secret, click Create, name the key and click Generate secret key. Your Client Id and Secret appear in the key list — treat the secret like a password.

  3. Step 3:Make your first call

    Send the secret in the X-AUTH-TOKEN header — for example to list your customers — and follow the API reference from there.

Invoicing API questions, answered

Does Invoice Office have an invoice API?
Yes. Invoice Office has a REST API that lets your own software work with your invoices, quotes, order confirmations, credit notes, customers, suppliers, products, purchases and CRM activities. All data endpoints live under /api/v1/.
Where is the API documentation?
The full API reference is public at https://app.invoiceoffice.com/api/v1/docs — you do not need an account to read it. It documents every endpoint, its parameters and its request and response schemas, and you can download the OpenAPI document from there.
Which plan includes the API?
The REST API is a Pro license feature (the Professional plan on our pricing page, €24.99 a month). Creating an API key and calling the API both require an active Pro license, and the Pro free trial includes it.
How do I authenticate with the API?
Create an API key and secret under Settings › Security center › API key and secret, then send the secret in the X-AUTH-TOKEN header on every request. Alternatively, exchange your e-mail address and password for a JWT at the Login Check endpoint and send it as a Bearer token.
Can I create invoices through the API?
Yes. You can create, update and delete invoices, and the same goes for quotes, order confirmations, credit notes, proforma invoices and packing notes. You can also convert a document into another type — a quote into an invoice, for example. A converted document starts as a concept, which you can then finalize.
Which data formats does the API support?
Responses are available as JSON, JSON-LD, XML, CSV and YAML. Updates use JSON merge patch, so you only send the fields you want to change.
Is there an OpenAPI (Swagger) specification?
Yes. The API is described in an OpenAPI 3.1 document, which you can download from the API reference and use to generate a client or import into a tool such as Postman.

More answers in our FAQ and help center.

Related

The records the API works with

Connect your software to Invoice Office

Browse the API reference, then start a free trial and create your API key. No credit card needed to try it.

Start free trialView the API docs