Skip to content
NACHA Navigator
Donate

Free X9.37 check image viewer

Open X9 files and see every check, front and back.

Drop in an X9.37 image cash letter to see each item’s front and back images, its MICR line and every record behind it — with bundle and cash letter totals checked. Parsing happens entirely in your browser.

  • Front & back check images
  • MICR line decoded
  • Control totals checked

Drop an X9 file here

Accepts .x9, .x937, .icl and .dat — any X9.37 file, EBCDIC or ASCII

Your file never leaves your browser

100% in-browser.

Your X9 file never leaves this device.

Secure processing

Your data never leaves your browser: the file is read and its check images are decoded on this device. Nothing is uploaded, stored or sent.

Fast analysis

Immediate parsing of your X9.37 files, with no upload limit. Files over 1 MB are parsed in a background thread so the page stays responsive.

Open about usage

Our public analytics count how often the viewer is used — never what your files contain.

0 bytes of your file are uploaded; the only requests are anonymous counters (a page view, a file opened). Check it yourself in your browser’s developer tools (Network tab).

Anatomy of an X9 file

Every check, as paper and as data.

An X9 file carries each check twice: the MICR line in an 80-character Check Detail record (type 25), and the front and back images in Image View records (50 and 52). The viewer lines the two up, field by field.

Record 04Check 1001 and its Check Detail record, from the sample file80 characters · 15 fields
  • Auxiliary On-Us check number3–17
  • Payor bank routing and check digit19–27
  • On-Us account number28–47
  • Item amount in cents48–57
04Check Detail
25 001001 053000125 4410023301/0000123456202610260000001G 1Y010B
  • Routing & IDs
  • Amounts
  • Dates
  • Names & text
  • Codes
  • Reserved

File structure

Cash letters, bundles, checks and images.

X9.37 files nest like the paper they replaced. Each control record states the counts and totals of what it closes; the viewer adds them up again from the items themselves and shows you any that disagree.

  1. Type01File HeaderOrigin, destination, test or production
  2. Type10Cash Letter HeaderOne business day’s deposit
  3. Type20Bundle HeaderA batch of items
  4. Type25Check DetailThe MICR line and amountper check
  5. Type26Check Addendum ABank of first deposit endorsement
  6. Type50Image View DetailFront, then backper side
  7. Type52Image View DataThe TIFF image bytesper side
  8. Type70Bundle ControlItems, amount and images in the bundle
  9. Type90Cash Letter ControlBundles, items, amount, images
  10. Type99File ControlCash letters, records, items, amount

Totals that must add up

Bundle Control (70)
items, amount, MICR-valid amount and images in its bundle
Cash Letter Control (90)
bundles, items, amount and images in its cash letter
File Control (99)
cash letters, records, items and the file total amount
Check Detail (25)
addendum count, and the routing number’s ABA check digit

Read as it was written

EBCDIC or ASCII, with 4-byte length prefixes, IBM record descriptor words or none at all — the framing is detected from the bytes, not the file name. Image data is never decoded as text.

What you get

Everything in the file, nothing made up.

The X9 Viewer replaces X9 Navigator, and every figure on screen now comes from your file: decoded records, real check images and totals recomputed from the items.

No. 01

Check image viewing

Front and back of every item, decoded from the TIFF Group 4 data in the file. Zoom, rotate, invert, compare sides and save any image as a PNG.

No. 02

Every record, decoded

All record types of X9.100-187 and DSTU X9.37-2003, field by field: MICR line, routing check digit, amounts, dates and code meanings, in EBCDIC or ASCII.

No. 03

Checked to the standard

Bundle, cash letter and file controls recomputed from the items — counts, amounts and image counts — with the value expected when one is off.

No. 04

Exports

Items as CSV or JSON, and every image as a PNG in one ZIP with a manifest. Account numbers stay masked unless you turn masking off.

Record types

Twenty-five record types, all decoded.

Each one is read with its own layout for the file’s standard level (X9.100-187-2008, 2013/2016 or DSTU X9.37-2003). Unknown types are kept and flagged, never dropped.

  • Type01File HeaderOpens the file: standard level, test or production, immediate destination and origin, and creation date and time.
  • Type10Cash Letter HeaderOpens a cash letter: the bundles sent together for one business day, with collection type, routing numbers and cash letter ID.
  • Type20Bundle HeaderOpens a bundle of items within a cash letter, with its business date, ID and sequence number.
  • Type25Check DetailOne check presented for payment: MICR line data (routing number, On-Us, Auxiliary On-Us), amount and item sequence number.
  • Type26Check Addendum ABank of first deposit (BOFD) endorsement: return location, BOFD business date, deposit account and payee.
  • Type27Check Addendum BImage archive reference for the check: microfilm sequence number and a variable-length image reference key.
  • Type28Check Addendum CA subsequent endorsement, one record per endorsing bank after the BOFD.
  • Type31ReturnOne returned item: payor bank routing number, On-Us, amount, return reason and forward bundle date.
  • Type32Return Addendum ABOFD endorsement on the returned item (same layout as type 26).
  • Type33Return Addendum BPayor bank details for the return: bank name, item sequence number, business date and payor account name.
  • Type34Return Addendum CImage archive reference for the returned item (same layout as type 27).
  • Type35Return Addendum DAn endorsing bank on the returned item (same layout as type 28).
  • Type40Account TotalsItem count and amount for a key account or account range.
  • Type41Non-Hit TotalsItem count and amount for items that matched no key account.
  • Type50Image View DetailDescribes one image view of the item (front or back): format, compression, creator and digital-signature settings. Its Image View Data record follows.
  • Type52Image View DataCarries the image bytes of the preceding Image View Detail, with the image reference key and optional digital signature.
  • Type54Image View AnalysisImage quality and usability test results for the preceding image view.
  • Type61Credit ReconciliationA credit for the deposit, within a cash letter or bundle.
  • Type62CreditA credit item (100 bytes).
  • Type68User RecordData defined by the record owner: the general format, or format 001 for a payee endorsement.
  • Type70Bundle ControlCloses a bundle with its item count, total amount, MICR-valid amount and image count.
  • Type75Box SummaryTotals for a box of bundles: destination, bundle count and box total.
  • Type85Routing SummaryItem count and amount totals for one routing number within the cash letter.
  • Type90Cash Letter ControlCloses a cash letter with its bundle, item and image counts, total amount, ECE institution name and settlement date.
  • Type99File ControlCloses the file with its cash letter, record and item counts and the file total amount.
Positions, data types and code values for every field.

Related tools

More free tools for payment files.

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

  • ACH · NACHA files

    NACHA Viewer

    Decode every record field by field, check control totals, hashes and routing check digits, and build reversal files.

    .ach · .txt

    Open the NACHA 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