Fortnox Integration for Inventory: VNDLY Sync Guide [2026]

Your inventory should show what is actually on the shelf. Your accounting should show what the company has sold and invoiced. The moment the same customer, article, and invoice has to be typed into both systems, a third job appears: finding and fixing the differences.

A Fortnox integration for inventory should reduce that job, not create a murky two-way sync where nobody knows which system is in charge. So VNDLY keeps the inventory and order flow in VNDLY, and pushes selected records on to Fortnox.

This guide walks through exactly what gets sent, which switches you use, and which gaps exist in the current integration. It is based on the actual VNDLY code as of August 2026.

Two systems need a clear division of labor

Fortnox has a large ecosystem. On its own integrations page, Fortnox lists over 500 connections, and the Inventory & Purchasing category alone covers article registers, orders, stock, and stocktaking. That does not make all connections the same.

Some systems try to turn Fortnox into the master record for inventory. Others only send accounting material. VNDLY sits between those extremes:

• VNDLY handles products, variants, stock levels, purchasing, sales, and fulfillment work.
• Fortnox receives customers, issued invoices, and, if you choose, product variants as articles.
• The flow runs from VNDLY to Fortnox. It is not a general two-way sync.

That boundary is deliberate. A stock quantity edited in Fortnox should not, for example, overwrite a balance built from receipts, picks, and stock transfers in VNDLY.

What VNDLY sends to Fortnox

The integration card in VNDLY has four separate switches, so you can start with customers and invoices without automatically filling Fortnox's article register.

Customers: created once, then updated

The switch is called Sync Customers and is on by default. A full manual sync includes active customers that are not archived.

The following fields are sent when they exist in VNDLY:

• Customer number and name
• Organization or VAT number
• Regular email and a dedicated invoice email address
• Phone, website, and notes
• Default currency
• Street address, postal code, city, and country code

Once Fortnox has created the customer, VNDLY stores the Fortnox customer number as an external link. The next time the same customer syncs, VNDLY updates against that number instead of searching by company name.

That is a small technical detail with large practical consequences. A name can be re-spelled. Two customers can have nearly identical names. A stored external ID is a safer anchor than free text.

Invoices: issued documents only, created as drafts

The Push Invoices switch is also on by default. The UI text is explicit: Push finalized invoices to Fortnox as drafts.

The manual sync selects invoices that:

• Are not in draft status
• Are not archived
• Are not credit notes

VNDLY sends the customer link, invoice date, due date, currency, VNDLY's invoice number as the order reference, notes, and the invoice lines. A line can carry article number, description, delivered quantity, price, discount, and VAT.

If the customer has no Fortnox link yet, VNDLY tries to create or sync the customer first. The invoice is only pushed once a Fortnox customer number exists. When Fortnox returns an invoice number, that too is stored as an external link, so the same VNDLY invoice is not created again on the next batch.

Landing as a draft is a control point. The inventory and sales team never re-types the lines, while whoever owns the books can review VAT, accounts, and the underlying data before the invoice moves on.

Articles: optional and off by default

Sync Articles is off by default. When you enable it, active VNDLY variants are sent to Fortnox as articles.

The article number becomes the variant's SKU. If the SKU is missing, the variant's internal ID is used as a fallback. The description is built from the product name and variant name. VNDLY can also send sales price, purchase price, unit, customs number, weight, and EAN barcode.

This is article data, not stock levels. Quantities on hand, locations, batches, serial numbers, and stock transfers do not travel along. If you need an operational inventory flow across multiple locations, that work should stay in VNDLY. Our guide to multi-location stock visibility shows why a single accounting field is not enough for that job.

The data path, step by step

Event in VNDLY	Result in Fortnox	Guard against errors
Active customer syncs	Customer created or updated	Fortnox customer number stored for the next sync
Issued invoice syncs	Invoice draft with lines created	Customer syncs first, invoice mapped afterwards
Active variant syncs (optional)	Article created or updated	SKU or internal ID used as the article number

The unusual part here is the ordering. Many integration pages settle for saying they sync "customers and invoices". VNDLY treats the dependency as an actual flow: customer first, invoice second, and an article number on the invoice line only when an article link already exists.

Connect VNDLY to Fortnox in five steps

1. Open Settings > Integrations

Log in to VNDLY and go to Settings > Integrations. Find the Fortnox card with the description "Swedish Accounting. Sync customers and invoices."

A user needs at least member permissions in VNDLY to connect and run the sync. Fortnox states on its integrations page that an integration license is included in the business packages and is used to connect external systems. Check your Fortnox agreement if the connection cannot be approved.

2. Click Connect Fortnox

VNDLY sends you to Fortnox's OAuth page. You approve the access at Fortnox, which means you never hand your Fortnox password to VNDLY.

After approval, the status shows Connected together with Company, Connected since, and Last sync. Check the company name before moving on, especially if you have access to several companies.

3. Choose exactly what may be sent

Start with Sync Customers and Push Invoices. Leave Sync Articles off until you and whoever owns the books have decided which system maintains the article register.

Auto Sync is off from the start. That is wise for the initial setup. An automatic process should be a repetition of a tested workflow, not the test itself.

4. Click Sync Now

The Sync Now button runs the selected parts. When the run completes, Last sync updates.

Under Recent Activity you see date, type, status, and the number of synced records. Status can be success, partial, or error. Partial means some records went through and others failed, so you can check the affected type without assuming the whole batch is lost.

5. Review the result in Fortnox

Run the first test with five customers and a handful of ordinary invoices. Check customer numbers, addresses, currency, invoice dates, due dates, VAT, prices, discounts, and quantities. If article sync is on, also check SKU, EAN, unit, and prices.

Only then decide about Auto Sync. Companies that want a clear approval point can happily keep using Sync Now manually.

From the founder: the draft is a safety valve

If your invoices start life as sales orders, read our guide to partial sales order fulfillment. It covers the steps before the invoice, where actual delivered quantity matters more than originally ordered quantity. For companies that want to reduce errors already at receiving, there is also the guide to receiving purchase orders in VNDLY.

Limitations to know before enabling auto sync

VNDLY's Fortnox connection does not do everything the Fortnox API technically can.

• Outbound only. VNDLY does not pull customers, invoices, or changes from Fortnox.
• No payment status back. A payment registered in Fortnox does not mark the VNDLY invoice as paid.
• No stock level sync. Article sync carries article information, not quantities or stock movements.
• No credit notes in version 1. Credit notes are filtered out of the batch and rejected by the invoice function.
• No VNDLY drafts. An invoice must be issued before it can be pushed.
• No automatic bookkeeping. The invoice is created as a draft in Fortnox and needs to be handled through your finance flow.

Fortnox's own documentation on inventory bookkeeping also distinguishes between the regular stock flow and bookkeeping with the Incoming Goods feature. VNDLY's connection does not try to replace or drive that Fortnox feature. Decide together with your accountant where inventory valuation and inventory bookkeeping should happen.

If you need to compare workflows across accounting systems, we have guides for VNDLY and Xero and VNDLY and QuickBooks. Fields and limitations differ, even when the heading "accounting integration" looks the same.

Common questions about VNDLY and Fortnox

Does VNDLY sync stock levels to Fortnox?

No. VNDLY can send active product variants as Fortnox articles, but not quantities on hand, locations, batches, serial numbers, or stock transfers.

Are invoices sent automatically?

That is your choice. You can run Sync Now manually or enable Auto Sync once the first batch has been reviewed. Push Invoices must be enabled.

What happens if the customer does not exist in Fortnox yet?

VNDLY tries to sync the customer before pushing the invoice. The invoice only proceeds once a Fortnox customer number has been stored.

Can the same invoice be created twice?

VNDLY stores the Fortnox invoice number as an external link after a successful sync. Later runs recognize that link and do not create the invoice again.

Can VNDLY import payments or credit notes from Fortnox?

No. Payments are not imported, and credit notes are not supported in the current version of the integration.

One inventory flow and one finance flow, without double typing

The best integration is not the one promising the most arrows between two logos. It is the one where the team can answer three questions: Which system owns the record? When is it sent? Where does the final check happen?

For VNDLY and Fortnox, the answers are concrete. VNDLY owns the inventory and order work. Customers, issued invoices, and optional articles are pushed out. Fortnox receives invoices as drafts for financial review.

---

Henrik Åberg is the founder of VNDLY. Before building inventory software, he ran a product company for 13 years with multiple warehouses and a growing order operation.