easy-fints

Python library with an optional FastAPI HTTP API adapter around python-fints.

PyPI package:

• easy-fints

Python import package:

• easy_fints

It currently supports:

• anonymous bank info lookup
• account listing
• balances
• transactions
• SEPA transfers
• TAN / decoupled confirmation flows
• payee verification (VoP) continuation

The package can be used in three ways:

• as a Python library
• as a FastAPI-based REST server
• as a Dockerized REST server

Quick Start

Requirements:

• Python 3.11+
• a bank account with FinTS/HBCI access
• valid FinTS credentials and server URL

Install from PyPI:

pip install easy-fints

For local development:

python -m venv .venv
source .venv/bin/activate
pip install -e .[dev]

Minimal .env:

FINTS_PRODUCT_ID=YourProductID
FINTS_PRODUCT_NAME=YourProductName
FINTS_PRODUCT_VERSION=YourProductVersion
FINTS_SESSION_TTL_SECONDS=300
FINTS_DEBUG_LEVEL=off
FINTS_DEBUG_FAIL_ONLY=0

A FinTS product ID can be requested via the official registration page:

• https://www.fints.org/de/hersteller/produktregistrierung

Usage Modes

• Library: import FinTS directly in your Python application
• REST server: run the built-in FastAPI service locally
• Docker: run the REST server through Dockerfile or docker-compose.yml

Library

Use the package directly in Python:

from easy_fints import (
    FinTS,
    TanRequiredError,
)

with FinTS(
    product_id="YourProductID",
    bank="12345678",
    user="your-user",
    pin="your-pin",
    server="https://bank.example/fints",
) as fints:
    try:
        accounts = fints.accounts()
        transactions = fints.transactions(days=30)
    except TanRequiredError as exc:
        print(exc.challenge.message)

REST Server

Run the optional local HTTP server with the bundled CLI:

fints-rest-server start
fints-rest-server status
fints-rest-server stop

Configuration priority for the CLI:

• explicit CLI flags like --host or --port
• values loaded from --env-file
• process environment variables
• built-in defaults

Installed CLI defaults:

• server host: 0.0.0.0
• server port: 8000
• PID file: .fints-rest-server.pid
• log file: .fints-rest-server.log

CLI examples:

fints-rest-server start --host 127.0.0.1 --port 9686
fints-rest-server start --env-file /etc/easy-fints.env
fints-rest-server stop

OpenAPI:

• http://127.0.0.1:8000/docs
• http://127.0.0.1:8000/openapi.json

Docker

The repository includes both Dockerfile and docker-compose.yml.

Start the REST server with Docker Compose:

docker compose up --build -d
docker compose logs -f api
docker compose down

Current Docker defaults:

• container port: 9686
• published port: 9686
• env file: .env
• log volume: ./logs:/app/logs

Docker OpenAPI:

• http://127.0.0.1:9686/docs
• http://127.0.0.1:9686/openapi.json

REST API

Optional HTTP endpoints:

• GET /health
• POST /readiness
• POST /bank-info
• POST /accounts
• POST /balance
• POST /transactions
• POST /transfer
• POST /transfer/retry-with-name
• POST /confirm
• GET /sessions/{session_id}
• DELETE /sessions/{session_id}

All operation endpoints accept a JSON body with a config object. Request values override env defaults.

Supported config fields:

• bank
• user
• pin
• server

Transfer Support

POST /transfer supports a single SEPA credit transfer per request.

Transfer request fields:

• source_account
• account_name
• recipient_name
• recipient_iban
• recipient_bic
• amount
• purpose
• endtoend_id
• instant_payment
• execution_date

Current behavior:

• account_name is required because python-fints.simple_sepa_transfer(...) expects the sender name explicitly
• instant_payment=true requests SCT Inst when the bank supports it
• execution_date=YYYY-MM-DD requests a dated transfer
• instant_payment and execution_date cannot be combined
• unsupported transfer products return HTTP 422 with error="unsupported_transfer_product"
• transfer challenge responses and final transfer responses include transfer_overview

Confirmation Flow

The API uses a session-based confirmation flow.

Typical sequence:

1. POST /transfer or another operation endpoint
2. either immediate 200, or a challenge response like 409 tan_required
3. continue with POST /confirm
4. repeat /confirm for decoupled app confirmation if needed
5. for payee verification, call /confirm with approve_vop=true
6. if the recipient name should be corrected after VoP, call POST /transfer/retry-with-name

Session helpers:

• GET /sessions/{session_id} inspects the current state
• DELETE /sessions/{session_id} cancels the active session

Session states currently used:

• awaiting_tan
• awaiting_decoupled
• awaiting_vop
• running
• resuming

Sessions are:

• stored in memory only
• process-local
• expired after an inactivity TTL

The TTL defaults to 300 seconds and can be changed with FINTS_SESSION_TTL_SECONDS.

Examples

The repository includes small scripts for manual API testing:

Library examples:

• examples/bank_info_lib.py
• examples/accounts_lib.py
• examples/balance_lib.py
• examples/transactions_lib.py
• examples/single_account_lib.py
• examples/transfer_lib.py

They use examples/lib_helper.py and talk directly to FinTS.

REST API examples:

• examples/bank_info_api.py
• examples/accounts_api_tan.py
• examples/balance_api_tan.py
• examples/transactions_api_tan.py
• examples/single_account_api_tan.py
• examples/transfer_api_tan.py

They use examples/api_tan_helper.py and read credentials from .env.

Optional helper-script env vars for manual transfer runs only:

• FINTS_TRANSFER_INSTANT_PAYMENT=true
• FINTS_TRANSFER_EXECUTION_DATE=YYYY-MM-DD

Documentation

Detailed REST API reference:

• docs/API.md

Transfer workflow:

• POST_transfer_workflow.md

High-level testing/verification notes:

• USECASE.md
• VERIFICATION.md

Development

Canonical entry points:

• easy_fints/library.py for Python callers
• easy_fints/api.py for the FastAPI/ASGI app

Core internal layering:

• easy_fints/client.py keeps the public FinTSClient facade stable
• easy_fints/_client_runtime.py, easy_fints/_client_reads.py, easy_fints/_client_transfer.py, and easy_fints/_client_confirmation.py split the main FinTS workflows by responsibility
• easy_fints/transaction_mapping/ contains the transaction normalization modules and debug source tracking

Important files:

• easy_fints/library.py
• easy_fints/api.py
• easy_fints/client.py
• easy_fints/helpers.py
• easy_fints/models.py
• easy_fints/transaction_mapping/

Basic checks:

python -m compileall easy_fints examples
.venv/bin/python -m pytest tests -q

Package build:

python -m build

GitHub Actions:

• CI runs on pushes to main and on pull requests
• publishing to PyPI runs when a GitHub Release is published

Packaging

Package name on PyPI:

• easy-fints

Import package in Python:

• easy_fints

Install from PyPI after the first published release:

pip install easy-fints

Deployment Notes

This project intentionally keeps the API simple:

• no server-side profile model
• no persistent credential store
• no server-managed account data
• no built-in authentication layer

Recommended deployment style:

• trusted network only
• TLS at the edge
• optional reverse proxy, VPN, mTLS, or network isolation depending on your stack
• operation logs are sanitized by default and do not store raw PINs, TANs, or raw FinTS payloads

Current limitation:

• active confirmation sessions are in-memory and process-local, so the simplest supported runtime is a single API process

Debug Logging

Optional transaction debugging can be enabled with environment variables:

• FINTS_DEBUG_LEVEL=off|summary|mapping|record_raw
• FINTS_DEBUG_FAIL_ONLY=1 to emit debug output only when a transaction is missing dates or amount after normalization

Debug entries are written to logs/debug.log.

Recommended troubleshooting setup for normalization issues:

FINTS_DEBUG_LEVEL=record_raw
FINTS_DEBUG_FAIL_ONLY=1

Notes:

• summary writes one compact entry per transaction fetch
• mapping adds selected field sources and visible raw key names per record
• record_raw also includes the raw transaction payload/representation and may contain sensitive bank data
• normalization happens through the modules in easy_fints/transaction_mapping/