From vendor bank details to ACH deadlines and ISO 20022 status codes, here is how treasury, AP/AR, payment operations, engineering and audit teams — and the AI agents working with them — use PayOps Kit.
Pages compute in your browser · the API stores nothing
Treasury: plan funding around banking days on both sides of the Atlantic
The problem
A payment that settles a day later than planned leaves an account short or cash idle. Treasury teams juggle the Federal Reserve calendar, TARGET2 for euro flows and UK bank holidays, and a Saturday holiday is observed differently by each: the Fed stays open the Friday before, while England and Wales take the next Monday.
How PayOps Kit helps
The business day calculator answers “is this a banking day?”, adds or counts business days and lists a year’s holidays for each calendar, with every holiday named and every observed day explained. Download the year as a calendar file for the team calendar. For US ACH, the ACH date calculator shows whether a file still makes a Same Day ACH window and when it settles.
Accounts payable: catch bad bank details before the payment run, not after the return
The problem
Vendor master data collects typos: a transposed digit in a routing number, an IBAN copied without its last character, a BIC with the wrong branch. Each one becomes a rejected payment, a return fee and a vendor asking where their money is — usually days later.
How PayOps Kit helps
Paste the whole list into the routing number, IBAN or BIC tool and see every line checked at once: ABA check digits, Federal Reserve prefixes and the bank behind each routing number where public data names it, IBAN length, BBAN structure and mod-97 check digits for every registry country, BIC format and country. Bank and branch codes are pulled out of each IBAN so they can be compared with the vendor’s letter. A pass proves the number is well formed, not that the account exists, so keep verifying new payees the usual way.
Accounts receivable: work ACH returns and NOCs with the deadlines in front of you
The problem
A debit comes back R10 or R07, a Notification of Change arrives with C01, and the question is always the same: what does the code mean, may the customer still dispute it, and by when do we have to act? The answers sit in the Nacha Operating Rules, which most AR teams don’t keep open.
How PayOps Kit helps
The code lookup explains every ACH return reason code, NOC code and SEC code, with each return code’s timeframe and whether it applies to consumer or corporate accounts. The ACH date calculator turns a settlement date into concrete deadlines: two banking days for most returns, 60 calendar days for unauthorized consumer debits, NOC timing and the five-banking-day reversal window. Both are informational and point back to the Rules and your ODFI agreement.
Payment operations: answer the questions that arrive every afternoon
The problem
Will a file sent at 2:50 p.m. Eastern settle today? Is a $1.2 million entry eligible for Same Day ACH? What does a pain.002 status of AC04 or AM04 mean, and how many decimals does a currency take? These questions interrupt the day, and the answers are scattered across operator schedules, ISO code lists and old emails.
How PayOps Kit helps
The ACH date calculator works out settlement from a submission time and an effective date: which Same Day window it makes, or why it settles the next banking day (the window closed, the amount is over the $1,000,000 limit — $10,000,000 from September 17, 2027 — or it is an IAT entry). The code lookup covers common ISO 20022 status reason codes and ISO 4217 currencies with their minor units, next to the ACH codes.
Payments engineers: the same checks from a script, a test or a service
The problem
Every payments codebase reimplements IBAN validation, an ABA check digit and a holiday table, and each copy drifts: a country added to the IBAN registry, a new Federal Reserve holiday, a Saturday rule handled the wrong way.
How PayOps Kit helps
Every tool is also a REST endpoint under /api/v1/, documented in an OpenAPI 3.1 file: GET for one value, POST for a batch. No key and no account, a per-visitor rate limit, and inputs that are never stored or logged. Each tool page shows the curl command for what you just typed, so going from the page to code takes one copy.
AI agents: give an assistant real checks instead of guesses
The problem
A language model asked whether an IBAN is valid, when an ACH return is due or whether Friday is a banking day will often answer confidently and wrongly: check digits and holiday rules are arithmetic, not language.
How PayOps Kit helps
PayOps Kit runs an MCP server at /mcp with a tool for each check — validate_routing_number, lookup_bank_by_routing_number, validate_iban, parse_bic, business_day_math, ach_return_deadline and more — each with a precise description and input schema, marked read-only. Connect Claude Code, Claude Desktop, Cursor or VS Code in one step; agents that prefer HTTP can read /llms.txt and call the REST API instead.
Tools and conceptsMCP serverllms.txtRead-only tools
No. 07
Audit & compliance
Audit and compliance: verify identifiers without sending them anywhere
The problem
Workpapers are full of LEIs, ISINs, CUSIPs and SEDOLs copied by hand, and check images whose written amount must match the figure. Pasting them into random websites can breach data-handling policy.
How PayOps Kit helps
The identifier tool verifies LEI, ISIN, CUSIP and SEDOL check digits (and a Luhn check) and detects the type for you; the check amount tool writes an amount in words and cross-checks written words against the figure. Tool pages compute in your browser and send nothing you type, which the site’s security policy enforces.
Every tool page computes its results in your browser with the page’s own JavaScript: nothing you type is sent anywhere, and the page’s security policy lets it talk only to this site. That makes it safe to check real routing numbers, IBANs and amounts.
The REST API and MCP server answer each request in memory and never store or log what you send. The only records kept are anonymous counters. Read the privacy page.
Try it with your own data
Paste a list of routing numbers or IBANs, work out an ACH return deadline, or connect your AI assistant to the MCP server in one command.
PayOps Kit is a free set of everyday payment-operations checks: US routing numbers, IBAN and BIC, banking-day calendars (US Federal Reserve, TARGET2, UK), ACH settlement and return deadlines, payment code lookups, and check digits for LEI, ISIN, CUSIP and SEDOL. Each tool has a page for people, a REST endpoint for scripts and an MCP tool for AI agents, all backed by the same code.
Is it free, and do I need an API key?
Yes, it is free, and no key or account is needed for the pages, the REST API or the MCP server. The API is rate-limited per visitor (about 120 requests a minute) so it stays available to everyone. Donations are welcome but never required.
Do you store what I check?
No. Tool pages compute every result in your browser and send nothing you type; to name a bank, the routing number page downloads the public list for the number’s first four digits, never the full number. The REST API and MCP server answer each request in memory and never store or log the inputs. The site keeps only anonymous counters, such as how many times a tool was used, never the values.
Does a valid IBAN or routing number mean the account exists?
No. A pass means the number is well formed: the right length and structure, and correct check digits. It does not prove that the account exists, is open, or belongs to the person you expect. Keep verifying new payees with your bank’s usual controls.
Where does the routing number tool get bank names?
From public data: the primary routing numbers banks report in FFIEC Call Reports, joined to FDIC BankFind for the legal name, headquarters and status, plus the routing numbers banks publish on their own websites. Every answer shows its source and date. The authoritative list, the Federal Reserve’s E-Payments Routing Directory, may not be redistributed, so it isn’t used: a valid number missing from our data can still be real, and you should confirm a number with the receiving bank or the Fed directory before sending funds.
Are the ACH deadlines official?
They are informational. The ACH date calculator applies the timeframes of the Nacha Operating Rules and the Federal Reserve’s Same Day ACH schedule to the dates you give it, but it is not a substitute for the Rules, your ACH operator’s schedule or your agreement with your bank, which may set earlier cut-off times.
How do I connect an AI agent?
Add the MCP server at /mcp to your client: in Claude Code, run claude mcp add --transport http payops-kit followed by the server URL; Claude Desktop, claude.ai, Cursor and VS Code accept it as a remote (Streamable HTTP) server. The API page has copy-ready snippets for each, and /llms.txt describes every tool for agents that use plain HTTP.