Elastic License 2.0 (ELv2)
OpenKSeF is released under the Elastic License 2.0.
What you can do
- Use OpenKSeF for internal purposes (business and personal)
- Modify the source code
- Distribute modified versions
- Self-host at no cost
Limitation
You may not offer OpenKSeF as a hosted or managed service (SaaS) to third parties. If you want to offer OpenKSeF commercially as a service, contact the author -- see COMMERCIAL.md.
Contributor License Agreement (CLA)
Contributions require signing a CLA. Details: CLA.md.
Full license text
Elastic License 2.0
URL: https://www.elastic.co/licensing/elastic-license
Acceptance
By using the software, you agree to all of the terms and conditions below.
Copyright License
The licensor grants you a non-exclusive, royalty-free, worldwide,
non-sublicensable, non-transferable license to use, copy, distribute, make
available, and prepare derivative works of the software, in each case subject to
the limitations and conditions below.
Limitations
You may not provide the software to third parties as a hosted or managed
service, where the service provides users with access to any substantial set of
the features or functionality of the software.
You may not move, change, disable, or circumvent the license key functionality
in the software, and you may not remove or obscure any functionality in the
software that is protected by the license key.
You may not alter, remove, or obscure any licensing, copyright, or other notices
of the licensor in the software. Any use of the licensor's trademarks is subject
to applicable law.
Patents
The licensor grants you a license, under any patent claims the licensor can
license, or chooses to license, to make, have made, use, sell, offer for sale,
import and have imported the software, in each case subject to the limitations
and conditions in this license. This license does not cover any patent claims
that you cause to be infringed by modifications or additions to the software. If
you or your company make any written claim that the software infringes or
contributes to infringement of any patent, your patent license for the software
granted under these terms ends immediately. If your company makes such a claim,
your patent license ends immediately for work on behalf of your company.
Notices
You must ensure that anyone who gets a copy of any part of the software from you
also gets a copy of these terms.
If you modify the software, you must include in any modified copies of the
software prominent notices stating that you have modified the software.
No Other Rights
These terms do not imply any licenses other than those expressly granted in
these terms.
Termination
If you use the software in violation of these terms, such use is not licensed,
and your licenses will automatically terminate. If the licensor provides you
with a notice of your violation, and you cease all violation of this license no
later than 30 days after you receive that notice, your licenses will be
reinstated retroactively. However, if you violate these terms after such
reinstatement, any additional violation of these terms will cause your licenses
to terminate automatically and permanently.
No Liability
As far as the law allows, the software comes as is, without any warranty or
condition, and the licensor will not be liable to you for any damages arising
out of these terms or the use or nature of the software, under any kind of
legal claim.
Copyright (c) 2026 OpenKSeF
Data and security disclaimer
OpenKSeF is software provided "as is" (AS IS), without any warranty.
In particular:
- The authors do not guarantee the security of data stored in your OpenKSeF instance
- The authors bear no responsibility for data loss, security breaches, or system malfunctions
- The user is fully responsible for configuring, securing, and maintaining their instance
- The authors have no access to data stored on self-hosted instances
OpenKSeF operates on tax data (invoices from KSeF). Before production deployment, we recommend:
- Security configuration review by a qualified person
- Implementing HTTPS, backups, and monitoring
- Compliance with data protection regulations (GDPR)
- Regular updates to the latest versions
warning
OpenKSeF is in beta. Use in a production environment with real tax data is at the user's own risk and responsibility. There may be changes in the API and data structure between versions.