Sellsy integration mapping
Connecting to Sellsy
Follow this guide to establish the connection to the Sellsy API.
Synchronized data
Entity | Key synchronized fields |
|---|---|
Customers | id, name, email |
Products | id, name_or_reference |
Prices | id, amount_excl_tax, currency |
Invoices | id, linked_customer, issue_date, status, number, quantity, amount_excl_tax, discounts, VAT, period, currency, description |
Credit Notes | same structure as invoices but with negative amounts |
How the integration works in detail
- Structured mapping: each Sellsy entity is translated according to a field-by-field mapping
- Smart product filtering: only non-archived items of a compatible type are imported
- Invoice lines: each line is analyzed individually to detect discounts, VAT, quantity, description, etc.
- Converted amounts: amounts excl. tax and discounts are also rendered in the base currency
- Billing periods: Fincome identifies the periods (period_start / period_end) when they are filled in Sellsy
- Credit note retrieval: credit notes are imported with their lines and associated with their original invoices
Good to know
- Duration of the first synchronization: a few minutes to several hours depending on the volume
- Daily synchronization: every night automatically
- Manual changes: never overwritten by a re-synchronization
- Sellsy API rate limit: handled automatically by Fincome
- Negative amounts for credit notes: interpreted automatically
Integration overview
Element | Detail |
|---|---|
Integration method | OAuth 2.0 or API token |
Supported entities | Customers, Products, Prices, Invoices, Credit notes |
Synchronization frequency | Daily (at night) |
Scope of the initial import | All the data available in Sellsy |
Synchronization method | REST API + pagination |
Sellsy data deletion | Not propagated (deletions in Sellsy are not replicated) |
Data settings
Behavior / Setting | How it works in Fincome |
|---|---|
Archived products | Automatic exclusion |
Invoice lines | Full import with discounts, VAT, periods, descriptions |
Excl./incl. tax calculations | Automatic (amount_tax_exc, tax_amount fields) |
Currency conversion | Applied according to the currency_code field + invoice date |
Credit note handling | Inverted amounts, but a structure identical to invoices |
Manual data | Editable without being overwritten during a new sync |
Technical mapping (Sellsy → Fincome)
Customers
Sellsy field | Fincome field |
|---|---|
id | original_id |
name | name |
Products & Prices
Sellsy field | Fincome field |
|---|---|
id (product) | original_id |
name or reference | name |
price_excl_tax | amount |
currency_code | currency_code |
id | product_id (price) |
Invoices
Sellsy field | Fincome field |
|---|---|
id | original_id |
date | date |
number | invoice_number |
status | status |
company_id | customer_id |
Invoice lines
Sellsy field | Fincome field |
|---|---|
id | original_id (line) |
quantity | quantity |
amount_tax_exc | amount_excluding_tax_after_discount |
tax_amount | tax_amount |
description | description |
period_start | period_start |
period_end | period_end |
currency_code | currency_code |
Credit Notes
Same structure as invoices, with:
- Negative amounts
- Credit-note-specific statuses
- References to the same types of lines
Next steps
- Check your KPIs in the MRR, Churn, and Cohort views
- Add other billing sources (Stripe, Chargebee, etc.)
- Enrich your customer data (segmentation, company size...)
- Schedule a session with your Customer Success to go further
Updated on: 03/07/2026
Thank you!