Sellsy integration mapping

Connection to Sellsy

Follow this guide to establish the connection to the Sellsy API.

Synchronized data

Entity

Synchronized key fields

Customers

id, name, email

Products

id, name_or_reference

Prices

id, amount_excl_tax, currency

Invoices

id, linked_client, issue_date, status, number, quantity, amount_excl_tax, discounts, VAT, period, currency, description

Credit Notes (Credit Notes)

same structure as invoices but with negative amounts

Detailed operation of the integration

• Structured mapping: each Sellsy entity is translated according to a field-by-field mapping
• Intelligent product filtering: only non-archived and compatible-type items 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 returned in the base currency
• Billing periods: Fincome identifies periods (period_start / period_end) when they are provided in Sellsy
• Credit note import: credit notes are imported with their lines and associated with their original invoices

Note

• Duration of the first synchronization: a few minutes to several hours depending on volume
• Daily synchronization: every night automatically
• Manual changes: never overwritten by a resynchronization
• Sellsy API rate limit: managed automatically by Fincome
• Negative amounts for credit notes: interpreted automatically

Integration overview

Item

Detail

Integration method

OAuth 2.0 or API token

Supported entities

Clients, Products, Prices, Invoices, Credit notes

Sync frequency

Daily (night)

Scope of initial import

All data available in Sellsy

Synchronization method

REST API + pagination

Deletion of Sellsy data

Not propagated (deletions in Sellsy are not replicated)

Data settings

Behavior / Setting

Operation in Fincome

Archived products

Automatic exclusion

Invoice lines

Full import with discounts, VAT, periods, descriptions

Excl. tax and incl. tax calculations

Automatic (field amount_tax_exc, tax_amount)

Currency conversion

Applied based on the currency_code field + invoice date

Handling of credit notes

Amounts reversed, but 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

email

email

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 (Credit Notes)

Same structure as invoices, with:

• Negative amounts
• Statuses specific to credit notes
• References to the same types of lines

Next steps

• View your KPIs in the MRR, Churn, and Cohorts 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: 01/06/2026