A free ACH validator and a paid one usually run the same checks. What you pay for is volume, integration and the tools around the check, not a better answer about whether the file is valid. This post sets out what a validator can check at all, what free tools cover, what paid tools add, and how to decide.
What any validator can check
A NACHA file is a fixed-width text file with rules that are either met or not. A validator can check every one of them:
- Record lengths, record order, and the block padding at the end of the file.
- Required fields present, reserved fields blank, dates in the right format and on banking days.
- Routing number check digits.
- Entry counts, entry hashes, and debit and credit totals in every batch control and the file control.
- SEC code, service class and transaction code agreement, including which codes require or forbid addenda records.
- Trace numbers that follow the originating bank's routing prefix and do not repeat.
The 12-point checklist walks through these by hand. A validator does them in seconds and tells you which record and field failed.
What no validator can check
Free or paid, a validator reads the file. It cannot see the bank.
- It cannot confirm an account exists, belongs to the named person, or has funds. A prenote or an account validation service does that.
- It cannot confirm your bank will accept the file. Banks add their own requirements on top of the NACHA rules, such as a specific immediate origin format or a cutoff time, and the bank makes the final decision on every file and every payment.
- It cannot tell you the amounts are right. A file that pays the wrong amount to the right account is perfectly valid.
Any tool that implies otherwise is describing a different product.
What free validators cover
Free validators come in three forms.
Online validators such as the FiSTWorks ACH Validator: upload a file, read the results. The FiSTWorks one runs the same rule engine as its paid plans, checks files containing any of the 12 NACHA SEC codes, and reports errors (the bank will reject), warnings (the bank may question) and information by line and field, in plain language. It needs no account. There is a monthly allowance per visitor, and a free account carries its own allowance; both are listed on the pricing page.
Open-source libraries for developers: a parser you call from your own code. Thorough when well maintained, but you are responsible for keeping the rules current and for building the reporting around it.
Your bank's upload check. Most portals reject a malformed file at upload. This is a validator too, but the slowest kind: you find out after you have built the file and often after the cutoff.
What paid tools add
Paid validation, whether a plan on a tool like FiSTWorks or a module in a larger payments platform, generally adds some of the following:
- Volume. Higher or unlimited monthly validation counts for teams that check many files.
- An API. Validation inside your own software or portal, so files are checked before a person ever sees them. FiSTWorks offers this to software platforms and banks.
- Generation. Software that builds the file from your data and checks it before it exists, so there is nothing to validate after the fact. That is what ACH Drafter does.
- Delivery and returns. Sending the checked file to the bank over SFTP and reading the bank's return and NOC files back.
- Team controls. Seats, roles, approval steps and an audit trail.
Notice that none of these is a stricter check. The rules are the rules.
How to decide
- You already produce ACH files and want them checked before upload, a few times a month. A free online validator is the right tool. There is no paid check it is missing.
- You check files every day, or several people do. The free allowance will run out; a paid plan is a volume purchase.
- You want validation inside your own product or customer portal. You need an API or an embeddable widget, which is a paid or contract arrangement everywhere.
- The files you are validating are built by hand and keep failing. The problem is upstream of validation. Software that generates the file correctly removes most of the checking.
Whichever you choose, validate before every upload. The cost of a check is seconds; the cost of a rejection is a day.