Free ACH & NACHA File Validator
Our free NACHA file validator is a powerful tool for finding and fixing errors in ACH files. It runs in your browser and sends no file data to our servers.
If you're looking for an on-premise or whitelabel version, please see our validator product page and contact us for more information.
What is an ACH Validator
An ACH file validator checks that a NACHA-formatted ACH file is structured correctly before you send it to your bank. ACH files use a fixed-width format where every record must follow exact rules — a single misaligned field, bad check digit, or incorrect total can cause your bank to reject the entire file. Our free ACH validator finds these errors instantly so you can fix them before submitting.
What Our ACH Validator Checks
The validator reviews your ACH file against NACHA formatting rules, including:
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Record structure — confirms File Header, Batch Header, Entry Detail, Addenda, Batch Control, and File Control records are present and correctly formatted
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Routing number check digits — verifies each routing number using the ABA check-digit algorithm to catch typos
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Entry hash and control totals — recalculates aggregate fields so you can confirm batch and file totals match
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Field-level formatting — flags fields that are the wrong length, type, or alignment
Hover over any field to see its meaning, and click an error to jump straight to the affected line.
Common ACH File Errors
Most ACH file rejections come from a handful of recurring issues:
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Incorrect entry hash or batch/file control totals
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Invalid or mistyped routing numbers
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Misaligned fields or records that aren't exactly 94 characters
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Missing or malformed batch/file control records
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Wrong service class or transaction codes
The validator identifies each of these with a description and the exact line, so troubleshooting takes seconds instead of hours.
Your ACH Files Stay Private
The ACH validator runs entirely in your browser. Your file is never uploaded to our servers — all validation happens on your own device, so sensitive payment data never leaves your computer.
Frequently Asked Questions
Is the ACH file validator free?
Yes. Our ACH validator is completely free to use, with no signup required.
Do you store my ACH file?
No. The validator runs entirely in your browser and never sends your file data to our servers. Your file stays on your device.
What file formats does the ACH validator support?
It validates standard NACHA-formatted ACH files — the fixed-width format U.S. banks use for ACH payments like payroll, vendor payments, and collections.
What does the validator check?
It verifies record structure, routing number check digits, entry hashes, control totals, and field-level formatting against NACHA rules.
Can I use this for large ACH files?
Yes. The validator handles files with tens of thousands of lines and errors in seconds.