Free NACHA file viewer & ACH validator
Drop in an ACH file to see every record decoded, color-coded and checked against the NACHA format — then build a reversal in a few clicks. Parsing happens entirely in your browser.
Drop a NACHA file here
Accepts .ach and .txt — any file of 94-character records
Your ACH file never leaves this device.
JavaScript on this page reads the file. Nothing is uploaded, stored or transmitted.
Viewing, validating and building reversals are free. No sign-up, ever.
Our public analytics show exactly what we count — never what your files contain.
Anatomy of a record
Every line of a NACHA file is a fixed-width record. Navigator names each field, colors it by what it holds and measures exactly where it sits — so you can see at a glance where the routing number ends and the amount begins.
Routing & IDs
Routing and account numbers, company, trace and batch IDs
Amounts & totals
Amounts in cents, counts and entry hashes
Dates
Creation, effective and settlement dates and times
Names & text
Company, receiver and description fields
Codes
Record, transaction, service-class and SEC codes
Reserved
Blank by specification; dots mark padding
Every record type, field by field: the NACHA file format reference
What it does
The same checks your bank runs before it accepts a file — record lengths, control totals, hashes and check digits — explained in plain language, line by line.
No. 01
Every record type — File Header (1), Batch Header (5), Entry Detail (6), Addenda (7), Batch Control (8) and File Control (9) — split into named, color-coded fields, with the right layout for PPD, CCD, CTX, WEB, TEL, IAT, returns and NOCs.
No. 02
Record length, control totals, entry hash, routing check digits, effective dates, SEC and transaction codes, and blocking-factor padding. Each problem is pinned to its line and column, with the expected value when there is a single right one.
No. 03
Pick the entries to undo — one, a whole batch or the entire file — and download a reversal file: transaction codes flipped, control totals recalculated and the REVERSAL company entry description set.
No. 04
Reconcile debit and credit totals, entry and addenda counts and entry hashes against your payment register before you send, then export the entries to CSV or JSON.
More samples
Each sample shows a different corner of the format. All names, account numbers and amounts are made up; nothing is uploaded either way.
CCD · Remittance addenda
A credits-only CCD batch paying vendors with one type 05 addenda each, and a debits-only CCD batch collecting invoices.
CTX · EDI 820
Two CTX payments whose ANSI X12 820 remittance advice spans several type 05 addenda records.
Returns · NOC
A file sent back by an RDFI: a PPD batch of returns (R01, R02, R03, R10, R15) and a COR batch of NOCs (C01, C02, C05).
Validation demo
A small payroll file damaged on purpose: totals that don’t add up, a bad check digit, an impossible date and more. Open it to see each problem pinned to its line and column, with the expected value when there is a single right one.
Reversal demo
Payroll credits, membership debits and a vendor payment, dated the previous banking day so the five-banking-day reversal window is open. Built in your browser for today’s date.
Building a file from scratch?
The NACHA Generator writes a valid file from a form or JSON — totals, entry hash and block fill included.
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Build a valid NACHA file in the visual builder — or send JSON to the free REST API. Control totals, entry hash and block padding are done for you, and the result opens right here in the viewer.
Questions
Short answers to what people ask most. The full answers, with real-world use cases for payroll, banking, treasury and compliance teams, are on the use cases page.
Looking for enterprise-grade NACHA file generation, batch processing, or automated ACH workflows? We’re developing advanced tools for financial institutions and treasury departments.