Skip to content
NACHA Navigator
Donate

Use cases

NACHA File Viewer & ACH Validation — Real-World Use Cases

From payroll validation to reversal generation and compliance audits, here is how teams across banking, fintech, and finance use NACHA Navigator every day.

100% in-browser processing — your file never leaves your device

Open the free NACHA file viewer
No. 01

Payroll teams

Payroll Teams: Validate ACH Payroll Files Before Submission

The problem

A payroll run that fails at the bank means employees do not get paid on time. Payroll teams often receive NACHA files from payroll software or third-party processors and have no easy way to verify them before submission. A single unbalanced batch, an invalid effective entry date, or a truncated record can cause the whole file to be rejected — sometimes discovered only after the submission window has closed.

How NACHA Navigator helps

Drop the payroll file into NACHA Navigator before you send it. The parser immediately shows every batch, entry, and control record with labeled fields, and the validator recomputes each batch and file total and the entry hash, flagging any that don’t match. You can confirm the effective entry date lands on the right pay date, verify the total debit and credit dollar amounts in the File Control record match your payroll register, and spot-check individual employee entries — account numbers, amounts, and individual names — without counting characters in a text editor.

Key conceptsPPD entriesEffective entry dateBatch control totalsEntry hash
No. 02

Banks & credit unions

Banks & Credit Unions: Troubleshoot Rejected or Malformed NACHA Files

The problem

ACH operations staff at financial institutions regularly receive originated files that fail pre-processing edits: wrong record lengths, missing File Control records, invalid routing number check digits, or batches whose entry counts do not match their control records. The rejection notice usually cites a record position and an edit code — not much help when you are staring at thousands of 94-character lines.

How NACHA Navigator helps

NACHA Navigator turns the raw file into a color-coded, record-by-record breakdown. Each record type (1, 5, 6, 7, 8, 9) is labeled, and clicking any field shows its name, position, expected format, and purpose. Every failed check is listed with its line, columns and the value it expected, so it is fast to jump to the batch the edit report flagged, compare the Batch Control entry/addenda count against the actual entries, and verify the receiving DFI routing number check digit — all without exposing customer data to any external system.

Key conceptsRecord type codesBlocking factor and block countEntry hashTrace numbersABA check digit
No. 03

Treasury & finance

Treasury & Finance: Audit Entry Details, Batch Totals, and Control Records

The problem

Treasury teams are accountable for every dollar that leaves the company through ACH origination. Reconciling a NACHA file against an AP run or a treasury workstation export means verifying that batch totals, entry counts, and company identification fields are exactly right — a tedious, error-prone process when done by hand.

How NACHA Navigator helps

With NACHA Navigator, an analyst can open the origination file and read the File Control record totals directly: total entry and addenda count, total debit dollars, total credit dollars. Batch Header records show the company name, company ID, and standard entry class for each batch, so it is easy to confirm the right originating entity and transaction type. Individual entries can be inspected for receiver names, amounts, and transaction codes (checking vs. savings, debit vs. credit).

Key conceptsTransaction codes 22/27, 32/37Company ID and batch numberCCD vs. CTX entriesFile vs. batch control totals
No. 04

Fintech developers

Fintech Developers: Learn and Debug the NACHA File Format

The problem

If you are building ACH origination into a product, you have to produce byte-perfect NACHA files — and the specification is a fixed-width format where every field lives at an exact character position. Off-by-one padding errors, wrong justification (left vs. right), and missing filler characters are the classic bugs, and they are nearly invisible in a diff.

How NACHA Navigator helps

NACHA Navigator doubles as an interactive reference for the format. Load a known-good sample file (one is built in) and click through every field to see its exact position, length, and rules — then load your generated file next and compare. Because each field is individually selectable and labeled, you can pinpoint exactly which column your generator got wrong. It is a faster feedback loop than resubmitting to a bank sandbox. The NACHA file format reference lists every field of every record type, and the NACHA Generator builds a valid file to compare against.

Key concepts94-character recordsJustification and paddingAddenda records and indicatorTrace number constructionSEC codes
No. 05

Operations teams

Operations Teams: Generate ACH Reversal Files for Erroneous Entries

The problem

Duplicate payment runs, wrong amounts, and payments to the wrong account happen. Nacha rules allow originators to reverse erroneous entries, but only within five banking days of settlement, and the reversing file must be formatted precisely: opposite transaction codes, full original amounts, and “REVERSAL” in the company entry description. Building that file by hand under time pressure is risky.

How NACHA Navigator helps

NACHA Navigator generates the reversal for you. Load the original file, select the entries that need reversing, choose the reason, and the tool produces a correctly balanced NACHA reversal file — transaction codes flipped, control totals recalculated, description set — ready to download and submit to your bank within the reversal window. Try it on the demo file.

Key conceptsFive-banking-day windowPermissible reasons: duplicate, wrong Receiver, wrong amount, wrong dateFlipped transaction codes“REVERSAL” entry description
No. 06

Compliance & audit

Compliance & Audit: Review ACH Origination Files

The problem

Auditors and compliance officers reviewing ACH origination need to verify that files match approved payment instructions, that company identification fields are correct, and that no unauthorized entries slipped into a batch. Requesting screenshots from operations or opening raw files in a text editor makes evidence-gathering slow, and uploading sensitive files to third-party web tools may violate data-handling policy.

How NACHA Navigator helps

Because NACHA Navigator runs entirely in the browser, compliance teams can inspect origination files on their own machines without any data leaving the device — consistent with strict data-handling requirements. The structured view makes it straightforward to document batch composition, originating company IDs, effective dates, and dollar totals for workpapers, and to trace any individual entry by its trace number.

Key conceptsCompany ID and nameImmediate origin and destinationTrace number audit trailBatch segregation

Privacy by design: your file never leaves your device

Every use case above shares one property: NACHA Navigator parses your ACH file entirely in your browser with client-side JavaScript. Nothing is uploaded, stored, or transmitted. That makes it safe to inspect production payment files containing real account and routing numbers — even under strict bank and enterprise data-handling policies.

You can check it: the viewer’s security policy only lets it talk to this site, and your browser’s developer tools (Network tab) show that opening a file sends nothing. Read the privacy page.

Try it with your own file

Upload a NACHA file (or explore the built-in sample) and see a field-by-field breakdown in seconds. Need to undo an erroneous entry? Generate a compliant ACH reversal file in a few clicks.

Analyze a NACHA fileGenerate an ACH reversal

Related tools

More free tools for payment files.

The same private, in-browser approach for the other formats that land on an operations desk.

  • New

    X9.37 · Image cash letter

    X9 Viewer

    Open X9.37 check image files in your browser: every item’s front and back images, its MICR line and the records behind it.

    .x9 · .x937 · .icl

    Open X9 Viewer

  • BAI2 · Balance reporting

    BAI2 Viewer

    Turn BAI2 bank reports into readable account summaries and transaction detail, with every type code explained.

    .bai · .bai2 · .txt

    Open BAI2 Viewer

  • Build files · REST API

    NACHA Generator

    Build a valid NACHA file with a visual form, or from JSON with the REST API. Control totals, entry hash and block padding are done for you.

    Read the API docs

    Open the generator

FAQ

Frequently Asked Questions

Something else? Email us or read the NACHA file format reference.

What is a NACHA file?

A NACHA file is a fixed-width text file format defined by Nacha (the National Automated Clearing House Association) for submitting ACH payments in the United States. Every line is exactly 94 characters and represents a record: a File Header (type 1), Batch Headers (type 5), Entry Details (type 6), optional Addenda (type 7), Batch Controls (type 8), and a File Control (type 9). Banks and payment processors use this format to originate direct deposits, vendor payments, debits, and other electronic transfers.

How do I read or open a NACHA file?

Because a NACHA file is plain text with fixed-width fields, it is technically readable in any text editor — but interpreting it by counting character positions is slow and error-prone. A NACHA file viewer like NACHA Navigator parses each record type automatically, labels every field (routing numbers, amounts, trace numbers, effective dates), and lets you click any field to see its meaning, position, and validation rules.

How do ACH reversals work?

Under Nacha rules, an originator may reverse an erroneous entry (duplicate, wrong amount, wrong account, or wrong date) by submitting a reversing entry within five banking days of the settlement date of the original entry. The reversal must be for the full amount, flow in the opposite direction, and include "REVERSAL" in the company entry description. NACHA Navigator can generate a properly formatted reversal file from your original entries, with the transaction codes flipped, the control totals recalculated and the REVERSAL description set.

Is my ACH file data secure when I use NACHA Navigator?

Yes. NACHA Navigator parses your file entirely in your browser using client-side JavaScript. The file is never uploaded to a server, never stored, and never transmitted over the network. Your account numbers, routing numbers, and payment data stay on your device the whole time.

Why was my NACHA file rejected by my bank?

Common rejection causes include incorrect record lengths (lines must be exactly 94 characters), unbalanced batch or file control totals, invalid routing number check digits, bad effective entry dates, missing blocking-factor padding (files must contain a multiple of 10 records), and malformed Standard Entry Class (SEC) codes. Loading the file into a viewer that labels every field makes these problems visible in seconds instead of hours, and NACHA Navigator checks for each of them automatically.

Does NACHA Navigator cost anything?

No. NACHA Navigator is free to use for viewing, validating, and generating reversal files, and so are the X9 Viewer, the BAI2 Viewer and the NACHA Generator. If it saves you time, donations are welcome but never required.