NACHA File Validator

Inspect and validate ACH/NACHA files directly inside Visual Studio Code.

NACHA File Validator helps developers, QA teams, payment operations, and analysts quickly understand ACH files and identify structural or control-total problems before a file moves to the next stage of a payment workflow.

Open your ACH file → Validate → Review results → Fix → Validate again.

Why use NACHA File Validator?

ACH/NACHA files are fixed-width payment files. A small formatting mistake or incorrect control total can be difficult to find by simply opening the file as text.

NACHA File Validator turns that raw file into a clear validation report directly inside VS Code.

Key benefits

• Find problems quickly — See validation issues without manually searching through the file.
• Jump directly to errors — Validation issues include line numbers that take you directly to the relevant record.
• Understand the file — Review file headers, batches, entries, and control records in an easier-to-read format.
• Reconcile control totals — Compare calculated values with the totals declared in File Control and Batch Control records.
• Explore transactions — Filter entries by batch, debit, or credit and inspect transaction details.
• Keep sensitive data local — ACH file processing is performed locally by the extension.
• Read-only validation — Your original ACH file is not modified.
• Stay in VS Code — Validate files without switching to another application.

What does it validate?

NACHA File Validator currently focuses on structural validation and important ACH control information.

File structure

Checks include:

• ACH record structure
• Record length
• File Header structure
• File Control structure
• Batch structure
• Entry records
• Addenda records
• Record sequencing and relationships

File Control reconciliation

The validator analyzes File Control information including:

• Batch count
• Block count
• Entry/Addenda count
• Entry hash
• Total debits
• Total credits

Calculated values are compared with the values reported by the ACH file.

Batch Control reconciliation

For each batch, the validator checks information including:

• Service class
• Entry/Addenda count
• Entry hash
• Total debits
• Total credits
• Company identification
• ODFI identification
• Batch number

Entry and transaction validation

The validator also examines information such as:

• Transaction codes
• Routing numbers and check digits
• Trace numbers
• Trace ODFI information
• Entry amounts
• SEC codes
• Addenda relationships
• Entry sequencing

Results at a glance

After validation, the results view provides several useful sections.

File Summary

Quickly see important information about the ACH file and its structure.

File Control Reconciliation

Compare calculated File Control values against the values contained in the file.

Batch Explorer

Select a batch and inspect its details without manually navigating through the raw file.

Entry Explorer

Browse entries and filter them by:

• All
• Credits
• Debits

Large entry lists can be explored progressively instead of displaying everything at once.

Validation Issues

Problems are presented in a dedicated table with useful information such as:

• Line number
• Record type
• Issue type
• Description
• Expected value
• Actual value

Click a Line button to jump directly to the corresponding line in the ACH file.

How to use it

1. Install NACHA File Validator

Install NACHA File Validator from the Visual Studio Code Marketplace.

2. Open an ACH/NACHA file

Open the file in Visual Studio Code.

3. Run the validator

Open the Command Palette:

Cmd+Shift+P on macOS
Ctrl+Shift+P on Windows/Linux

Then run:

NACHA Validator: Validate NACHA File

4. Review the results

The validator opens a results view containing the file summary, reconciliation information, batches, entries, and validation issues.

5. Fix and validate again

If problems are found, use the reported line numbers to locate the relevant records, make your changes, and run the validator again.

Who is it for?

Developers

Validate ACH files while developing payment or banking integrations.

QA and test teams

Catch structural problems and incorrect control totals during testing.

Payment and operations teams

Quickly inspect ACH files without manually decoding fixed-width records.

Analysts and business users

Understand the contents of an ACH file without needing to interpret every field manually.

Privacy and sensitive payment data

Your ACH file is processed locally by the extension.

NACHA File Validator is designed so that the ACH file content being validated is not transmitted to an external validation service.

The extension:

• Processes validation locally.
• Does not require uploading an ACH file to a website.
• Does not modify the original ACH file.
• Displays validation results inside VS Code.
• Masks account-number information in the results where applicable.

Important

ACH files can contain highly sensitive financial information.

Do not share production ACH files publicly when reporting an issue.

When requesting support, use synthetic or properly redacted data whenever possible.

Important scope

NACHA File Validator is a structural and validation aid.

A successful validation means that the checks currently implemented by this extension passed. It does not mean that the file has been certified as fully compliant with every requirement of the Nacha Operating Rules, a financial institution, or a particular ACH processing environment.

Different ACH use cases can have additional requirements that are outside the current scope of the extension.

For production payment processing, continue to follow the applicable Nacha Rules, financial-institution requirements, and your organization's controls.

Planned improvements

The goal is to make ACH development and testing easier over time.

Potential future improvements include:

• VS Code Problems integration for easier issue navigation.
• ACH file comparison for regression testing.
• CI/CD validation for automated payment-file checks.
• Configurable validation profiles for different workflows.
• Additional SEC-code rules and transaction-specific validation.
• Synthetic ACH file generation for safe development and testing.
• More detailed issue explanations and remediation guidance.
• Additional payment-file analysis and safety checks.

Feedback helps determine which improvements are most useful.

Help make it better

Found a bug, missing validation rule, or useful idea?

I'd love to hear from you.

Email: nchendu.ai@gmail.com

You can also report issues or suggest improvements through the project's GitHub repository.

When reporting an issue:

• Please use synthetic or redacted ACH data.
• Never include real account numbers.
• Never include production payment files containing sensitive information.
• Include the validation message and relevant record type when possible.

If you find it useful

If NACHA File Validator saves you time:

• Install it and try it with test or synthetic ACH files.
• Share it with teammates who work with ACH files.
• Report bugs you encounter.
• Suggest validation rules that would make your workflow easier.
• Send feedback about what you'd like to see next.

The best improvements will come from real-world developer and payment-workflow feedback.

Technical reference

The extension is based on publicly documented ACH/NACHA file structures and conventions.

For authoritative ACH requirements, always refer to the applicable Nacha Rules and your financial institution or ACH processor requirements.

This extension is not affiliated with or endorsed by Nacha unless explicitly stated otherwise.

License

This project is licensed under the MIT License.

Copyright © 2026 NChendu Software.