SIE
The SIE format is an open standard for transferring accounting data between different softwares by different software vendors. SIE has been adopted by software suppliers in Sweden to become a de facto standard for transferring accounting data.
The SIE file format used by Fortnox is based on version 4. Version 4 is a text based foramt using IBM PC8-bits extended ASCII (codepage 437). There is also a version 5 of SIE defined, but it seems not to be supported with Fortnox.
Specifications of the SIE 4 file format are available at:
Specifications of the SIE 5 file format are available at:
Fortnox
Fortnox provides real-time and high performance access to accounting data in SIE format through APIs.
The performance is at least an order of magnitude better than accessing the same data through regular APIs. In a test case, 27 years worth of annual balances could be retrieved in 10 seconds. 27 years of transactions could be retrieved also in 10 seconds, with a size of approximately 12 MB.
Invantive Fortnox-driver
The Invantive Fortnox-driver has as of June 6, 2025 limited support for SIE files through the following views and table function:
- View
SieTypes: a list of SIE file types (1 = Annual balances, 2 = Period balances, 3 = Item balances, 4 = Transactions). - View
SieAnnualBalanceFiles: a list of annual balances in SIE format. - View
SiePeriodBalanceFiles: a list of period balances in SIE format. - View
SieItemBalanceFiles: a list of annual balances in SIE format. - View
SieTransactionFiles: a list of annual balances in SIE format. - Table function
SieFileByType: base of the previous four views.
Currently Invantive does not yet provide parsed access to the data in the SIE format. Invantive studies whether a parser can and will be added to split the data in:
- Generic and identification information
- Chart of accounts
- Balance items / verification items
Availability
The SIE file view will be available starting release 24.0.730 of Invantive UniversalSQL.