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Project Documentation · Quickstart Guide · Community · Blog

GoDoc Build Status Coverage Status Go Report Card Apache 2 licensed


A configurable FTP/SFTP server and Go library to interactively test ACH scenarios to replicate real world originations, returns, changes, prenotes, and transfers.

If you believe you have identified a security vulnerability please responsibly report the issue as via email to Please do not post it to a public issue tracker.

Project status

This project is used in production at an early stage and might undergo breaking changes to reach a stable status. We are looking for community feedback so please try out our code or give us feedback!

Getting started

We publish a public Docker image moov/ach-test-harness from Docker Hub or use this repository. No configuration is required to serve on :2222 and metrics at :3333/metrics in Prometheus format.

Pull & start the Docker image:

$ docker-compose up
harness_1  | ts=2021-03-24T20:36:10Z msg="loading config file" component=Service level=info app=ach-test-harness version=v0.3.0 file=/configs/config.default.yml
harness_1  | ts=2021-03-24T20:36:10Z msg="Loading APP_CONFIG config file" app=ach-test-harness version=v0.3.0 APP_CONFIG=/examples/config.yml component=Service level=info
harness_1  | ts=2021-03-24T20:36:10Z msg="loading config file" component=Service level=info app=ach-test-harness version=v0.3.0 APP_CONFIG=/examples/config.yml file=/examples/config.yml
harness_1  | ts=2021-03-24T20:36:10Z msg="matcher: enable debug logging" level=info app=ach-test-harness version=v0.3.0
harness_1  | 2021/03/24 20:36:10   Go FTP Server listening on 2222
harness_1  | ts=2021-03-24T20:36:10Z msg="listening on [::]:3333" level=info app=ach-test-harness version=v0.3.0

You can then use an FTP client that connects to localhost:2222 with a username of admin and password of secret. Upload files to the outbound/ directory and watch for any responses.

After setup inspect the configuration file in ./examples/config.yml and setup some scenarios to match uploaded files.

      RootPath: "./data"
      Hostname: ""
      Port: 2222
        Username: "admin"
        Password: "secret"
      PassivePorts: "30000-30009"
        Files: "/outbound/"
        Return: "/returned/"
        Address: ":3333"
    Debug: false
  # ValidateOpts can use all values from
  ValidateOpts: {}
    # Entries that match both the DFIAccountNumber and TraceNumber will be returned with a R03 return code.
    - match:
        accountNumber: "12345678"
        traceNumber: "121042880000001"
          code: "R03"

The full config for Responses is below:

# All populated fields must match for the action to be applied to the EntryDetail
  # Match the DFIAccountNumber on the EntryDetail
  accountNumber: <string>
    min: <integer>
    max: <integer>
    value: <integer>       # Either min AND max OR value is used
  individualName: <string> # Compare the IndividualName on EntryDetail records
  routingNumber: <string>  # Exact match of ABA routing number (RDFIIdentification and CheckDigit)
  traceNumber: <string>    # Exact match of TraceNumber
  entryType: <string>      # Checks TransactionCode. Accepted values: credit, debit or prenote.
  # Copy the EntryDetail to another directory
    path: <string> # Filepath on the FTP server

  # Send the EntryDetail back with the following ACH change code
    code: <string>
    data: <string>

  # Send the EntryDetail back with the following ACH return code
    code: <string>


Return debits between two values

  - match:
      entryType: "debit"
        min: 100000 # $1,000
        max: 120000 # $1,200
        code: "R01"

Return a specific TraceNumber

  - match:
      # This matches ./examples/ppd-debit.ach
      traceNumber: "121042880000001"
        code: "R03"

Correct an account number

  - match:
      # This matches ./examples/utility-bill.ach
      accountNumber: "744-5678-99"
        code: "C01"
        data: "744567899"

Copy debit entries for a routing number

  - match:
      entryType: "debit"
      routingNumber: "111222337"
        path: "/fraud-doublecheck/"

Getting help

channel info
Project Documentation Our project documentation available online.
Twitter @moov You can follow's Twitter feed to get updates on our project(s). You can also tweet us questions or just share blogs or stories.
GitHub Issue If you are able to reproduce a problem please open a GitHub Issue under the specific project that caused the error.
moov-io slack Join our slack channel (#ach) to have an interactive discussion about the development of the project.

Supported and tested platforms

  • 64-bit Linux (Ubuntu, Debian), macOS, and Windows


Yes please! Please review our Contributing guide and Code of Conduct to get started! Checkout our issues for first time contributors for something to help out with.

This project uses Go Modules and uses Go 1.14 or higher. See Golang's install instructions for help setting up Go. You can download the source code and we offer tagged and released versions as well. We highly recommend you use a tagged release for production.

Test coverage

Improving test coverage is a good candidate for new contributors while also allowing the project to move more quickly by reducing regressions issues that might not be caught before a release is pushed out to our users. One great way to improve coverage is by adding edge cases and different inputs to functions (or contributing and running fuzzers).

Tests can run processes (like sqlite databases), but should only do so locally.


Apache License 2.0 See LICENSE for details.