ACH / NACHA Validator US
Check a US ACH (NACHA) file - structure, control totals, entry hash and ABA check digits - in your browser, nothing uploaded.
What is an ACH / NACHA file?
An ACH (NACHA) file is the fixed-width text format used for batch electronic payments in the United States — payroll, vendor payments and consumer debits. Every record is exactly 94 characters, grouped into a File Header, one or more batches of entries and control records. This free tool validates the record structure, the routing-number check digits, the entry hash and the control totals entirely in your browser — no file is ever uploaded.
About the ACH / NACHA validator
ACH (Automated Clearing House) is the batch electronic payment network used across the United States for payroll, vendor payments, and consumer collections. Files follow the Nacha format: fixed-width records of exactly 94 characters, grouped in blocks of 10, with a File Header (type 1), one or more batches (Batch Header 5, Entry Detail 6, optional Addenda 7, Batch Control 8) and a File Control record (type 9).
ValidateFin parses every record locally in your browser and checks the whole file: each record is 94 characters, the routing number check digit follows the ABA 3-7-1 algorithm, and the entry hash, total debits, total credits, entry/addenda count, batch count and block count in the Batch Control and File Control records all match what the detail records actually contain. No ACH file is ever uploaded to a server.
Key facts
- ACH files are fixed-width: every record is exactly 94 characters, in blocks of 10.
- Record types: 1 File Header, 5 Batch Header, 6 Entry Detail, 7 Addenda, 8 Batch Control, 9 File Control.
- The routing number check digit uses the ABA 3-7-1 weighting (mod 10).
- The entry hash is the sum of the 8-digit RDFI routing numbers, truncated to the last 10 digits.
- Batch and File Control records must match the real totals, counts and hash of the entries.
Frequently asked questions
What is an ACH / NACHA file?
It is the standard file format for electronic payments in the United States, defined by Nacha. It contains one or more batches of credit or debit entries in fixed-width 94-character records.
How is an ACH routing number validated?
The 9-digit routing number is checked with the ABA 3-7-1 algorithm: the first eight digits are weighted 3, 7, 1 repeating, and the ninth (check) digit makes the weighted sum a multiple of 10.
What is the entry hash?
The entry hash is the sum of the first 8 digits of every RDFI routing number in a batch (or the whole file), truncated to the rightmost 10 digits. It lets the receiving bank confirm no entries were lost or altered.
Is my ACH file uploaded anywhere?
No. The file is read and validated entirely in your browser using JavaScript. No ACH data is ever sent to a server.
Which record types does the validator check?
File Header (1), Batch Header (5), Entry Detail (6), Addenda (7), Batch Control (8) and File Control (9), including all control totals, counts and the entry hash.
Can I validate both credits and debits?
Yes. The validator recognises credit and debit transaction codes for checking, savings, general-ledger and loan accounts, and checks them against the batch service class code.