ksef

A lightweight, framework-agnostic Python client for the Polish National e-Invoicing System (Krajowy System e-Faktur - KSeF) API 2.0.

This library is designed to be simple, synchronous (ideal for frameworks like Django or Flask), and relies on requests for HTTP communication and cryptography for RSA token encryption required by the authentication process.

Features

• Full implementation of the KSeF API 2.0 endpoints (Auth, Sessions, Invoices, Certificates, Permissions, Batch, Limits).
• Built-in automatic handling of the complex token authentication flow (Challenge -> RSA Encryption -> Init -> Wait -> Redeem).
• Automatic KSeF error parsing into readable Python exceptions (Error, AuthError, TimeoutError).
• Clean, Pythonic syntax with proper type hinting and Context Manager support.

Installation

Install the package and its dependencies using pip:

pip install ksef

(Note: If installing from source, you can run pip install -e . in the directory containing pyproject.toml)

Quick Start & Example Usage

Here are some common examples of how to use the client using Python best practices (context managers and specific exceptions).

1. Initialization, Authentication & Context Management

To connect to KSeF, you need your NIP (Tax Identification Number) and an Authorisation Token generated in the KSeF portal. It is recommended to use the client as a Context Manager (with block) to ensure the underlying HTTP session is correctly closed.

fromksefimportClientfromksef.exceptionsimportAuthError, Error# By default, test=True connects to the test environment (api-test.ksef.mf.gov.pl)withClient(test=True) asclient:
try:
print("Logging into KSeF...")
client.login(nip='1111111111', token='YOUR_KSEF_AUTHORISATION_TOKEN')
print(f"Login successful! Active Token: {client.token}")
# You can now safely make other KSeF calls...status=client.session_status()
print(f"Session reference: {status.get('referenceNumber') ifstatuselse'None'}")
exceptAuthErrorase:
print(f"Authentication failed: {e}")
exceptErrorase:
print(f"KSeF API Error: {e}")

2. Sending an Invoice (Online Mode)

You no longer need to extract tokens manually; the client automatically uses its authenticated token for the required Session-Token header.

fromksefimportClientfromksef.exceptionsimportErrorinvoice_payload= {
"invoiceHash": {
"hashSHA": {
"algorithm": "SHA-256",
"encoding": "Base64",
"value": "base64_encoded_sha256_hash_of_xml"
},
"fileSize": 1024
},
"invoicePayload": {
"type": "plain",
"invoiceBody": "base64_encoded_xml_invoice_content"
}
}
withClient(test=True, nip='1111111111', ksef_token='YOUR_TOKEN') asclient:
try:
client.login() # Authenticates using credentials from initializationresponse=client.invoices.send_online(invoice_data=invoice_payload)
print("Invoice sent successfully!")
print(f"Reference Number: {response.get('referenceNumber')}")
exceptErrorase:
print(f"Failed to send invoice: {e}")

3. Querying Invoices

You can search for invoices within a specific date range:

search_criteria= {
"queryCriteria": {
"subjectType": "subject1",
"type": "incremental",
"acquisitionTimestampThresholdFrom": "2023-10-01T00:00:00Z",
"acquisitionTimestampThresholdTo": "2023-10-31T23:59:59Z"
}
}
withClient(test=True) asclient:
client.login(nip='1111111111', token='YOUR_TOKEN')
response=client.invoices.query_metadata(
filters=search_criteria, params={"PageSize": 10, "PageOffset": 0}
)
print(f"Found {len(response.get('items', []))} invoices in the current page.")

4. Terminating the Session

It's good practice to terminate your session when you're done, even when using the context manager.

withClient(test=True) asclient:
client.login(nip='1111111111', token='YOUR_TOKEN')
# ... perform operations ...print("Terminating KSeF session...")
client.sessions.terminate_current()

Architecture

The client is split into modular managers mimicking the KSeF domain logic:

• client.auth - Authentication flows
• client.sessions - Session management
• client.invoices - Invoice sending, querying, and downloading
• client.certificates - Certificate operations
• client.permissions - Permission management
• client.batch - Batch operations
• client.limits - API limit inquiries