ACH File Parser

A robust Python-based parser for ACH (Automated Clearing House) transaction report files with fixed-width format.

Features

✅ Flexible Field Extraction

• Parses delimiter-separated fields (using - as separator)
• Extracts last column as remarks to handle any pattern (P-pattern or C-pattern)
• Supports multi-page reports (form feed separated)

✅ Comprehensive Data Extraction

• Report metadata (Report ID, Bank Name, Branch, Currency, Maker/Checker IDs)
• Transaction details (SNO, Account, Customer Name, Amount, Date, Status)
• Summary totals (Transaction counts and amounts)

✅ Robust Logging

• Console output with timestamps
• Rolling file logs (10MB max per file, 5 backups)
• Debug logging for troubleshooting

✅ Multiple Output Formats

• Console display with formatted tables
• JSON export for data processing
• Extensible for CSV/Excel export

File Structure

ach_ui_dbtl_file_based/
├── main.py                    # Application entry point
├── ach_parser.py              # ACH parser logic
├── export_to_json.py          # JSON export utility
├── logging_config.py          # Logging configuration
├── requirements.txt           # Python dependencies
├── .gitignore                 # Git ignore rules
├── .env.example              # Environment variables template
└── parsed_ach_data.json      # Exported transaction data

Installation & Setup

1. Create Virtual Environment

python3 -m venv venv
source venv/bin/activate

2. Install Dependencies

pip install -r requirements.txt

3. Configure Environment (Optional)

cp .env.example .env
# Edit .env with your settings

Usage

View Parsed Data in Console

source venv/bin/activate
python ach_parser.py

Output:

REPORT METADATA
================================================================================
REPORT_ID           : TF0504-01
BANK_NAME           : MURSHIDABAD D C C B LTD.
RUN_DATE            : 19/01/2026  10:32
BRANCH              : 99944
CURRENCY            : INR
MAKER_ID            : 0009991
CHECKER_ID          : 0000000

SNO    CUST ACCT          CUSTOMER NAME                            DATE         AMOUNT       REMARKS
================================================================================
1      122001447784       Mr. ATUL  DEY                            19/01/26     26.26        P0126049D07E0?IOCL LPG SUBSIDY
2      122005893950       Mr. SUMEJAHAN  BIBI                      19/01/26     26.25        P01260491D89C?HPCL LPG SUBSIDY
...

Export to JSON

python export_to_json.py

Output: parsed_ach_data.json

{
  "metadata": {
    "report_id": "TF0504-01",
    "bank_name": "MURSHIDABAD D C C B LTD.",
    ...
  },
  "summary": {
    "tot_processed": {
      "debit_count": "0",
      "credit_count": "178",
      "credit_amount": "41132.29"
    }
  },
  "transactions": [
    {
      "sno": "1",
      "cust_acct": "122001447784",
      "lpg_susp": "93615999445",
      "customer_name": "Mr. ATUL  DEY",
      "jrnl_no": "514103",
      "date": "19/01/26",
      "amount": "26.26",
      "sys": "23-DEP-PROCESSED",
      "message": "23-DEP-PROCESSED",
      "cr_suspense": "",
      "suspense_msg": "",
      "remarks": "P0126049D07E0?IOCL LPG SUBSIDY"
    },
    ...
  ]
}

Transaction Field Details

Field	Description	Example
SNO	Serial Number	1, 2, 3...
CUST_ACCT	Customer Account Number	122001447784
LPG_SUSP	LPG Suspense Code	93615999445
CUSTOMER_NAME	Customer Name	Mr. ATUL DEY
JRNL_NO	Journal Number	514103
DATE	Transaction Date	19/01/26
AMOUNT	Transaction Amount	26.26
SYS	System Status Code	23-DEP-PROCESSED
MESSAGE	Processing Message	23-DEP-PROCESSED
REMARKS	Remarks/Reference Code	P0126049D07E0?IOCL LPG SUBSIDY

Supported Remarks Patterns

The parser flexibly handles different remarks patterns:

• P-pattern: P0126049D07E0?IOCL LPG SUBSIDY
• C-pattern: C012634266856?MDM BURWAN BLOCK
• Any pattern: Takes the last column regardless of prefix

Logging

Logs are written to:

• Console: Real-time output during execution
• File: logs/app.log (rotating, 10MB max, 5 backups)

Log levels can be configured in logging_config.py:

from logging_config import setup_logging
setup_logging(log_level=logging.DEBUG)  # Change to DEBUG for verbose output

Example: Using in Your Code

from ach_parser import ACHParser, get_logger
from logging_config import setup_logging

# Setup logging
setup_logging()
logger = get_logger(__name__)

# Parse ACH file
parser = ACHParser('path/to/ach_file.txt')
transactions, metadata, summary = parser.parse()

# Access data
print(f"Parsed {len(transactions)} transactions")
for txn in transactions:
    print(f"{txn['sno']}: {txn['customer_name']} - ₹{txn['amount']}")

# Export to JSON
from export_to_json import export_to_json
export_to_json(transactions, metadata, summary, 'output.json')

Testing

To test with sample data:

python ach_parser.py

The parser includes debug logging for troubleshooting:

logger = get_logger(__name__)
logger.debug(f"Parsing transaction: {line}")

Known Limitations

• Assumes fixed-width format with - delimiters between main fields
• Remarks must be the last column (no fields after remarks)
• Form feeds (\f) are used to separate pages

Future Enhancements

• CSV export support
• Excel export support
• Database storage integration
• Validation and error correction
• Support for different ACH report formats
• Batch processing multiple files
• Web API for file upload and parsing

Dependencies

• python-dotenv: Environment variable management
• pytest: Testing framework
• black: Code formatting
• flake8: Code linting

See requirements.txt for exact versions.

License

Internal use only.

Support

For issues or questions, check the logs in logs/app.log for detailed error information.