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Vasu KasipuriNetSuite Architect · Agentic AI

Tools / TOOL-001Status · In service

NACHA file validator

A free NACHA file validator for ACH payment files: it checks the structure, routing numbers, and control totals that banks verify on receipt, and tells you what to fix in NetSuite when something fails.

Runs entirely in your browser. Your file never leaves your computer. This is a pre-flight check to catch common rejections, not a substitute for your bank's or Nacha's compliance validation.

Drop a NACHA file here

.ach or .txt · max 10 MB · processed on this page, never uploaded

Paste file contents instead

What is a NACHA file?

A NACHA file is the plain-text format used to send batches of ACH payments to a bank. Nacha, the body that governs the ACH network in the United States, defines it down to the character: every line is a record of exactly 94 characters, and every field lives at fixed positions inside that line.

A file opens with a file header, then one or more batches. Each batch has a header, entry records that carry the individual payments, and a control record with totals. The file closes with a file control record that totals everything, padded with lines of 9s until the line count is a multiple of ten.

That rigidity is the point. The receiving bank does not parse your intent; it reads position 30 through 39 and expects an amount. One character out of place and the whole file can bounce.

What this NACHA file validator checks

The checks mirror what receiving banks verify first: record structure and ordering, the 94-character rule, file header constants, service class and SEC codes, transaction codes, the ABA check digit on every routing number, amount formats, addenda consistency, and every control total: entry counts, entry hash, debit and credit totals, batch and block counts.

Every finding names the line, the field, and the exact character positions, so you can see the problem in the raw record instead of guessing. Files generated by NetSuite's Electronic Bank Payments also get a targeted fix hint, because I have spent enough hours on the wrong side of a bank rejection notice to know the fix is rarely in the file itself.

Why banks reject ACH files

In practice, rejections cluster around a few mechanical causes. A hand-edited file whose control totals no longer reconcile. A vendor routing number with a typo that fails its check digit. A file saved through an editor that trimmed the trailing spaces every record needs. A company ID that does not match the bank's setup. An effective date that is not a real banking day.

All of these are visible in the file before you upload it. That is the gap this tool covers: thirty seconds of validation against the published format, on your own machine, before the bank's nightly cycle finds the problem for you.

Frequently asked questions

Is my file uploaded anywhere?
No. The validator is JavaScript running on this page. Your file is read in your browser's memory, checked there, and never sent over the network, logged, or stored. You can verify this in your browser's developer tools: the network tab stays silent while you validate.
Why did my bank reject my ACH file?
The most common causes are mechanical: control totals that do not match the entries, a routing number that fails its check digit, lines that are no longer exactly 94 characters after someone edited the file, a company ID that does not match what the bank has on file, or an invalid effective entry date. This validator catches that whole class of problem before the bank does.
What does the entry hash check?
The entry hash is a checksum built from routing numbers. You add up the first 8 digits of the routing number of every entry in a batch, keep the rightmost 10 digits of the sum, and write the result in the batch control record. The file control record carries the same calculation across all batches. Banks recompute it on receipt; if it does not match, an entry was altered, added, or dropped after the totals were written.
What does this tool not check?
Anything only your bank can know. It cannot confirm that an account exists, that funds are available, that you are inside your bank's processing window, or that your company is authorized for a given SEC code. It also does not validate every rule for less common SEC codes such as IAT. Treat a clean result as a pre-flight pass, not as compliance approval.
Does it work with NetSuite Electronic Bank Payments files?
Yes, that is the workflow it was built around. ACH files generated by NetSuite's Electronic Bank Payments SuiteApp validate like any other NACHA file, and most findings include a specific fix: which vendor record, company bank detail, or EFT template field to correct in NetSuite before regenerating the file from Payment File Administration.

All sample data on this page is fictional. Routing numbers are fabricated to pass or fail the check digit deliberately and belong to no real bank.

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