FastACH

.NET library for reading and writing ACH files

Continuous integration

Branch	Build status
master

Installation

.NET 8.0, .NET 9.0, .NET 10.0

PM> Install-Package FastACH

Add namespace to the program

using FastACH;
using FastACH.Builders; // For using AchFileBuilder

Usage

Reading ACH file

var achFile = await AchFile.Read("ACH.txt");

achFile.WriteToConsole(); // Output to console

// Line map can be used for the error reporting
var lineMap = new List<(IRecord record, uint line)>();
var achFile = await AchFile.Read("ACH.txt", lineMap);

Reading ACH file to colorful console

var achFile = await AchFile.Read(name);
achFile.WriteToConsole();

Writing ACH file using AchFileBuilder (Recommended)

The AchFileBuilder provides a fluent API for building ACH files with less boilerplate code.

Simple Example - Credit and Debit Transactions

var achFile = new AchFileBuilder()
    .With(
        ImmediateDestination: "123456789",
        ImmediateOrigin: "987654321",
        ImmediateDestinationName: "Bank of America",
        ImmediateOriginName: "My Corporation")
    .WithBatch(batch => batch
        .With(
            CompanyId: "1234567890",
            OriginatingDFIID: "12345678",
            CompanyEntryDescription: "PAYROLL",
            CompanyName: "My Company")
        .WithCreditTransaction(
            amount: 1500.00m,
            routingNumber: "111111111",
            accountNumber: "987654321",
            receiverName: "John Doe")
        .WithDebitTransaction(
            amount: 500.00m,
            routingNumber: "222222222",
            accountNumber: "123456789",
            receiverName: "Jane Smith"))
    .Build();

await achFile.WriteToFile("ACH.txt");

Advanced Example - With All Optional Fields

var achFile = new AchFileBuilder()
    .With(
        ImmediateDestination: "123456789",
        ImmediateOrigin: "987654321",
        ImmediateDestinationName: "PNC Bank",
        ImmediateOriginName: "Microsoft Inc.",
        ReferenceCode: "REF12345",
        FileIdModifier: 'A')
    .WithBatch(batch => batch
        .With(
            CompanyId: "1234567890",
            OriginatingDFIID: "12345678",
            CompanyEntryDescription: "PAYROLL",
            CompanyName: "My Company",
            ServiceClassCode: 200,
            entryClassCode: "PPD",
            CompanyDiscretionaryData: "DISCRETIONARY",
            CompanyDescriptiveDate: new DateOnly(2024, 1, 15),
            EffectiveEntryDate: new DateOnly(2024, 1, 31),
            OriginatorsStatusCode: '1',
            BatchNumber: 1)
        .WithCreditTransaction(
            amount: 1500.00m,
            routingNumber: "111111111",
            accountNumber: "987654321",
            receiverName: "Employee One",
            receiverId: "EMP001",
            discretionaryData: "PAY")
        .WithAddenda(
            addendaTypeCode: 5,
            addendaInformation: "Salary payment for January 2024",
            addendaSequenceNumber: 1))
    .Build();

await achFile.WriteToFile("ACH.txt");

Multiple Batches Example

var achFile = new AchFileBuilder()
    .With("123456789", "987654321")
    .WithBatch(batch => batch
        .With("1234567890", "12345678", "PAYROLL", "Company A")
        .WithCreditTransaction(1000.00m, "111111111", "ACCT001", "Employee 1")
        .WithCreditTransaction(1200.00m, "222222222", "ACCT002", "Employee 2"))
    .WithBatch(batch => batch
        .With("0987654321", "87654321", "INVOICE", "Company B")
        .WithDebitTransaction(500.00m, "333333333", "ACCT003", "Customer 1")
        .WithDebitTransaction(750.00m, "444444444", "ACCT004", "Customer 2"))
    .Build();

await achFile.WriteToFile("ACH.txt");

Writing ACH file (Manual Approach)

var achFile = new AchFile()
{
    FileHeader = new FileHeaderRecord()
    {
        ImmediateDestination = "123456789",
        ImmediateOrigin = "123456789",
        FileCreationDate = DateOnly.FromDateTime(DateTime.Now),
        FileCreationTime = TimeOnly.FromDateTime(DateTime.Now),
        FileIdModifier = 'A',
        ImmediateDestinationName = "PNC Bank",
        ImmediateOriginName = "Microsoft Inc.",
        ReferenceCode = "00000000"
    },
    BatchRecordList =
    {
        new BatchRecord()
        {
            BatchHeader = new BatchHeaderRecord()
            {
                ServiceClassCode = 200,
                CompanyName = "companyName",
                CompanyDiscretionaryData = "companyDiscretionary",
                CompanyId = "companyID",
                CompanyEntryDescription = "EntryDescr",
                CompanyDescriptiveDate = new DateOnly(2011, 02, 03),
                EffectiveEntryDate = new DateOnly(2011, 01, 02),
                OriginatingDFIID = "DFINumber"
            },
            TransactionRecords =
            {
                new TransactionRecord
                {
                    EntryDetail = new EntryDetailRecord()
                    {
                        TransactionCode = 22,
                        ReceivingDFIID = 12345678,
                        CheckDigit = '9',
                        DFIAccountNumber = "1313131313",
                        Amount = 22M,
                        ReceiverIdentificationNumber = "ID Number",
                        ReceiverName = "ID Name",
                        DiscretionaryData = "Desc Data",
                        AddendaRecordIndicator = true,
                    },
                    AddendaRecords = new List<AddendaRecord>
                    {
                        new AddendaRecord()
                        {
                            AddendaInformation = "Monthly bill"
                        }
                    }
                },
                new TransactionRecord()
                {
                    EntryDetail = new EntryDetailRecord()
                    {
                        TransactionCode = 27,
                        ReceivingDFIID = 12345678,
                        CheckDigit = '9',
                        DFIAccountNumber = "1313131313",
                        Amount = 27M,
                        ReceiverIdentificationNumber = "ID Number",
                        ReceiverName = "ID Name",
                        DiscretionaryData = "Desc Data",
                        AddendaRecordIndicator = false,
                    }
                }
            }
        }
    }
};

await achFile.WriteToFile("ACH.txt");

Perfomance results

I created a benchmark to compare reading performance between FastACH and very popular ChoETL.Nacha library.

Method	NumberOfEntries	Mean	Error	Gen0	Gen1	Gen2	Allocated
FastACH	1000	11.62 ms	NA	-	-	-	949.88 KB
ChoetlNacha	1000	908.52 ms	NA	561000.0000	555000.0000	555000.0000	3770936.66 KB
FastACH	10000	31.50 ms	NA	-	-	-	9297.73 KB
ChoetlNacha	10000	5,316.70 ms	NA	2485000.0000	2427000.0000	2425000.0000	37579633.04 KB
FastACH	100000	214.57 ms	NA	7000.0000	6000.0000	2000.0000	92815.55 KB
ChoetlNacha	100000	43,563.12 ms	NA	31105000.0000	30491000.0000	30491000.0000	375791391.55 KB