OnlineCheckWriter

OnlineCheckWriter, powered by Zil Money, prints, mails, and electronically sends payments from your own bank accounts. Agents create and mail checks, send ACH, wire, RTP, and virtual card payouts, manage payees and wallets, and collect money through payment links.

Verified 144 actions API key available

OnlineCheckWriter website Platform Documentation Capability data verified 2026-08-25

An approved bill reaches its payment date in the accounting system

Agent reads the payee, the amount, the terms, and the supporting invoice

Agent resolves the payee's stored bank account and picks a rail from the terms

Get Payment Info confirms no payment already exists against this bill reference

Reversible rails send unattended, with the invoice in the same envelope or attachment

An instant payment proposal posts to the accounts payable channel instead of sending

The controller approves any instant payment, because that rail has no reversal

What This Integration Enables

OnlineCheckWriter, powered by Zil Money, is not a gateway. It is an outbound payments desk that draws on your own bank accounts, and it is unusual in how many rails it puts behind one payee record. The same supplier can be paid by a printed check, a check you post through the carrier with an invoice in the envelope, an emailed check they print themselves, ACH, wire, real-time payments, or a single-use virtual card sent to their email when you have no bank details at all. On top of that sits a document mailing service, a spend card program with network-enforced restrictions, gift cards, and inbound collection through payment links and manual ACH debits.

Breadth like that is a liability when a person is clicking through it and an asset when an agent is choosing. FlowRunner agents resolve the payee, pick the rail from the invoice terms, attach the supporting documents, and track the payment to settlement through one status route that covers every rail. What they do not do is pick the irreversible rail on their own, which is where FlowRunner's human-in-the-loop discipline sits on this connector.

Without FlowRunner

One rail for everything Every supplier gets a check because that is what the process has always produced

Invoices mailed separately The remittance detail arrives in a different envelope than the payment it explains

Deleted rather than voided A check is removed to fix a mistake, and the audit trail loses the record with it

With FlowRunner

Rail chosen from the terms Each payment takes the rail its terms and its urgency actually call for

Documents travel with payment The invoice and the remittance stub go in the same envelope as the check

Voided with the record intact A printed or mailed check is voided so it cannot be cashed and the history survives

Use Case Scenarios

A bill run that mails the invoice with the check

Approved bills come out of QuickBooks Online on the payment date. For each one the agent uploads the supporting invoice with Upload Attachment, creates a remittance voucher itemizing what the payment covers, and calls Send Check Mail Payment with both attached, so the supplier receives the check and the paperwork that explains it in the same envelope. Where one supplier is owed for several invoices, Quick Pay Bundle Mail posts the checks together in one envelope rather than paying carrier fees per check. Calculate Mail Check Fee runs first whenever the shipping type comes from a rule, because express delivery can cost more than the check.
Onboarding a payee so the first payment does not bounce back

A new supplier submits their details. The agent runs Validate Routing Number before anything is stored, since a wrong routing number is accepted at creation and only fails when money moves. It creates the payee and their bank account, and it treats the bank account holder name as the field that matters most, because a name that does not match what the receiving bank holds is what returns an ACH days later. Where the supplier will be paid from a wallet rather than directly from a bank account, Fund Wallet By ACH runs ahead of the payment date, since it settles over several business days and the balance does not rise immediately.
Spend cards with limits the network enforces

A project needs a card for a contractor. The agent issues one with Create Spend Card against a funded wallet, setting a limit that resets on the chosen interval and restrictions on merchant names, category codes, countries, cities, and permitted hours. Those restrictions are enforced by the card network rather than by the flow, which means they hold even when nothing is watching. Transactions come back through List Card Transactions and post to Xero. When the project closes, Update Spend Card Status suspends the card, and closure happens only on a deliberate instruction, since closing is not reversible.

Human-in-Loop Highlight

Read this connector's action list for what is missing. A check that has been printed or posted can be stopped with Void Check, and Track Mail Check will tell you where it is. An ACH that goes to the wrong account comes back with a returned status, late and annoying but recoverable. A virtual card can simply not be used. Send Instant Payment (RTP) has none of that. Funds land in seconds, the transfer is irrevocable, and across all 144 operations there is no reverse, no recall, and no void that reaches it. So the agent proposes the rail and the fastest one stops for a person: "Bill 8812 for Harbor Supply, 14,750 dollars, terms say due today. Proposed rail is instant payment to their RTP-enabled account. This cannot be recalled once sent. Approve, or fall back to same-day ACH?" The controller answers. Every other rail on this connector runs unattended, because every other rail leaves the company somewhere to stand.

Agent processes routinely

Detects exception requiring judgment

Clear match Continues automatically

Ambiguous Routes to human via preferred channel

Human decides

Agent resumes with decision

Agent Capabilities

144 actions

Your Bank Accounts

List Bank Accounts Lists the bank accounts you pay from, newest first, with optional keyword search. These are your accounts, not payee accounts.
Get Bank Account Retrieves one bank account in full, including its bank details, address, and approval status.
Create Bank Account Adds a bank account to pay from. The vendor's route is a batch accepting up to twenty accounts at once, so the reply is an array even for one.
Update Bank Account Updates a bank account's name, number, or address. Unlike the create route this one is not batched.
Delete Bank Account Permanently removes a bank account. Detach it from any pending payment first, since the vendor does not check and a payment drawing on a deleted account fails at settlement.
List Check Templates Lists the check design templates available to your account, whose identifiers a bank account takes as its template.
Validate Routing Number Checks a routing number and returns the bank it belongs to. Worth calling before creating a bank account, since a wrong routing number is accepted at creation and only fails when money moves.
Add Bank Account Signature Uploads a signature image to print on this account's checks.
List Bank Account Signatures Lists the signature images stored against a bank account.
Add Bank Account Logo Uploads a company logo to print on this account's checks.
Start Micro-Deposit Verification Sends two small test deposits to a bank account and starts its verification. A government identity document is part of the same request, and the deposits take one to three business days to land.
Confirm Micro-Deposit Verification Confirms verification by reporting the two deposit amounts the customer saw on their statement, in dollars.
Get Verification Status Reports where a bank account's micro-deposit verification has got to.
Start Instant Verification Mints a short-lived session token for instant bank verification. This is the server half only, since the token has to be handed to the verification widget in a browser.

Wallets

List Wallets Lists your wallets with their balances. A wallet is the funding source for ACH, wire, real-time, virtual-card, and spend-card payments.
Get Wallet Retrieves one wallet with its current balance.
List Wallet Transactions Lists a wallet's ledger, every credit and debit with its status code. This is the reconciliation feed, since it sees funding, withdrawals, payments, and card spend in one place.
Transfer Between Wallets Moves money from one of your wallets to another within the same account. Instant, and it never touches a bank.
Fund Wallet By ACH Pulls money from one of your bank accounts into a wallet by ACH. It settles over one to three business days, so the wallet balance does not rise immediately.
Get ACH Wallet Funding Retrieves one ACH wallet-funding request and its status.
List ACH Wallet Fundings Lists your ACH wallet-funding requests.
Create Fund Request Creates a request to fund a wallet by incoming domestic or international wire, and returns the wire instructions to give the depositor. Use it when money is coming from somewhere you do not control.
Get Fund Request Retrieves one wire fund request and whether the money has arrived.
List Fund Requests Lists your wire fund requests.
Withdraw By ACH Moves money out of a wallet into one of your own bank accounts by ACH. Same-day is a separate, faster and dearer rail, so switch it on deliberately.
Get ACH Withdrawal Retrieves one ACH wallet withdrawal and its status.
List ACH Withdrawals Lists your ACH wallet withdrawals.
Withdraw By Wire Moves money out of a wallet into one of your own bank accounts by wire transfer. Same day when sent before the cut-off, and dearer than ACH.
Get Wire Withdrawal Retrieves one wire wallet withdrawal and its status.
List Wire Withdrawals Lists your wire wallet withdrawals.
Withdraw By Check Mail Withdraws from a wallet by printing and posting a physical check. Both addresses are stored custom addresses referenced by identifier rather than inline text, so create them first.
Get Check Mail Withdrawal Retrieves one mailed-check wallet withdrawal and its status.

Payees

List Payees Lists the people and companies you pay, with optional keyword search.
Get Payee Retrieves one payee in full.
Create Payee Creates one payee. The vendor's route is a batch, so the reply is an array even for a single payee.
Update Payee Updates a payee's details. Fields you omit are left alone.
Delete Payee Permanently removes a payee.
Create Payee Bank Account Stores a payee's bank details so ACH, wire, and real-time payments can reach them. The account holder name must match the legal name exactly as the receiving bank holds it, since a mismatch is what returns an ACH days later.
Update Payee Bank Account Updates a payee's stored bank details.
Get Payee Bank Account Retrieves one of a payee's stored bank accounts.
List Payee Bank Accounts Lists a payee's stored bank accounts, whose identifiers the send-payment routes take.
Delete Payee Bank Account Removes one of a payee's stored bank accounts.

Quick Pay

Quick Pay Check Creates a printable check in one call, taking the recipient inline rather than as a stored payee. The shortest path from owing someone money to a check.
Quick Pay eCheck Emails the recipient a check they print themselves. The destination email is required, since that is the whole delivery mechanism.
Quick Pay Mail Check Prints and posts a physical check to an inline address. The state must be the two-letter code, since the vendor rejects the long form.
Quick Pay Bundle Mail Posts several existing checks together in one envelope to one address. Cheaper than mailing each separately when a supplier is owed for many invoices.
Quick Pay ACH Sends an ACH payment straight to bank details supplied inline. The vendor gates ACH sending behind a support conversation, so a new account is refused here until it is enabled.
Quick Pay Wire Sends a wire transfer to bank details supplied inline.
Quick Pay Virtual Card Issues a single-use virtual card to the recipient's email for the amount owed. The vendor describes this program as beta and enables it per account.
Quick Pay Mail PDF Posts a PDF fetched from a public URL to an address. This moves no money: it is a document mailing shortcut.

Checks

List Checks Lists checks with optional status, keyword, reference, and per-column filtering. A column and search type together do a targeted lookup, so an exact payee name finds one payee's checks without matching memos.
Get Check Retrieves one check in full.
Create Check Creates one check against a stored bank account and payee. The vendor's route is a batch, so the reply is an array even for one, and creating a check does not print, mail, or email it.
Update Check Updates an unprinted check. The bank account and amount are required even when unchanged, so read the check first and pass its current values through.
Delete Check Permanently deletes a check. Deleting is not voiding: a check already printed or mailed should be voided so the record survives for the audit trail.
Delete Checks (Bulk) Deletes many checks in one call.
Print Checks Renders one or more checks onto a printable PDF in the chosen paper layout, and returns its URL.
Print Checks With Attachment Renders checks together with their attachments into one printable PDF. Switch to asynchronous mode for a large run, and the vendor reports the finished file through its own webhook.
Void Check Voids a check so it can no longer be cashed, keeping the record.
Mark Check As Cleared Marks a check as posted against your bank statement. This is a bookkeeping flag and it does not move money.
Get Check Voucher Retrieves the remittance stub attached to a check.
Add Check Attachment Attaches a document to a check, which prints alongside it when the attachment print route is used.
List Check Attachments Lists the documents attached to a check.
Get Check Attachment Retrieves one attachment's details.
Delete Check Attachment Removes a document from a check.

Check Mailing

List Mailing Options Lists the shipping types, paper types, and inform types your account may use when mailing checks. Call this rather than trusting the numeric identifiers in the documentation, since the set is per account.
Create Mail Check Posts an existing check as physical mail. Shipping to a custom address makes the stored from address, to address, and shipping type all required; leave it off to mail to the payee's own address.
Calculate Mail Check Fee Prices a check mailing without sending it, using the same parameters as the mail route. Call it first when the shipping type is chosen by a rule, since express delivery can cost more than the check.
Track Mail Check Returns the carrier, tracking code, and delivery state for a mailed check.
Add Mail Attachment Adds a PDF that will be posted in the same envelope as the check. Give either a public file URL for the vendor to fetch, or the file itself.
List Mail Attachments Lists the PDFs that will be posted with a check.
Delete Mail Attachment Removes a PDF from a check's mailing.
Create Email Check Emails an existing check to the payee to print themselves. A payee email is optional only when the payee record already carries one.

Sending Payments

Send ACH Payment Pays a stored payee by ACH from a wallet or bank account. The payee bank account is required, so create it first.
List ACH Payments Lists the ACH payments you have sent, optionally filtered by your own reference number.
Send Wire Payment Pays a stored payee by wire transfer from a wallet or bank account.
List Wire Payments Lists the wire payments you have sent.
Send Instant Payment (RTP) Pays a stored payee over the real-time payments network. Funds land in seconds and the transfer is irrevocable, and the receiving bank must be enabled for it or the payment is refused.
List Instant Payments Lists the real-time payments you have sent.
Send Virtual Card Payment Sends a stored payee a single-use virtual card for the amount owed. No bank details are needed, which is why this rail exists.
List Virtual Card Payments Lists the virtual cards you have sent.
Send Check Mail Payment Pays a stored payee by printing and posting a physical check. Attachment identifiers go in the same envelope, which is how an invoice travels with its check.
List Check Mail Payments Lists the mailed-check payments you have sent.
Get Payment Info Reports where an outgoing payment has got to, whichever rail sent it. One identifier and one route covers ACH, wire, real-time, virtual card, and check mail alike.
Upload Attachment Uploads a file and returns an attachment identifier for a mailed check payment. Give either a public file URL for the vendor to fetch, or the file itself.
Get Attachment Returns a short-lived signed URL for viewing or downloading an uploaded attachment.
Delete Attachment Permanently deletes an uploaded attachment. It cannot be retrieved again afterwards.

Direct Deposits

Create Direct Deposit Sends an ACH direct deposit to bank details supplied inline, with the recipient's details in one call. This is the payroll-shaped route, where the stored-payee equivalent is the ordinary ACH send.
Get ACH Status Reports the current ACH status of a check-backed direct deposit.
Get ACH Status History Returns every status a direct deposit has been through rather than just the latest. This is where a returned status shows up after a completed one, which the single-status route can hide.

Collecting Money

Create Payment Link Creates a hosted page customers pay you through, deposited into the chosen bank account. The short URL becomes part of the public address.
List Payment Links Lists your hosted payment links.
Create Link Payment Charges a customer through a payment link, once or on a recurring schedule. Send either inline banking information or a stored customer bank account, not both, and the stored account is the safer half.
Get Link Payment Retrieves one payment-link charge by its reference identifier.
List Link Payments Lists the charges taken through your payment links.
Initiate Link Direct Deposit Turns an accepted payment-link charge into an ACH pull. It works only from the accepted and viewed statuses, and the deposit bank account must be approved for ACH.
Create Link Customer Creates a customer record for payment links, so repeat charges do not re-collect their details.
Get Link Customer Retrieves one payment-link customer.
Update Link Customer Updates a payment-link customer's details.
Create Customer Bank Account Stores a payment-link customer's bank details so future charges do not need them again.
Get Customer Bank Account Retrieves a payment-link customer's stored bank account.
Update Customer Bank Account Updates a payment-link customer's stored bank account.
Initiate Manual ACH Pulls money from a payee's bank account into your wallet. This is a debit rather than a payment: it takes money from someone else, so their authorization has to be on file and the account must be enabled for ACH.
Get Manual ACH Retrieves one manual ACH debit request.
List Manual ACH Lists your manual ACH debit requests.
Get Received Payment Reports where an incoming payment has got to, whether it arrived through a payment link or a manual ACH.

Cards

List Credit Cards Lists the credit cards on your account that can fund a payment.
Pay From Credit Card Funds a payment from a credit card rather than a bank account. The vendor requires an invoice document and a card image as proof, and both files travel with the request.
Create Spend Card Issues a virtual or physical spend card against a wallet, with a limit that resets on the chosen interval. The restriction settings are the point: merchant names, category codes, countries, cities, and permitted hours are enforced by the card network rather than by your flow.
Get Spend Card Retrieves one spend card's details, masked number, limit, and status.
List Spend Cards Lists the spend cards on your account.
Show Spend Card Details Returns the card's full number and security code, encrypted. The vendor discourages this, since reading or storing a full card number pulls your system into card-data compliance scope.
Update Spend Card Changes a spend card's limit, interval, label, or restrictions. Restriction lists replace the stored set, so send every merchant, country, or city you want to keep.
Update Spend Card Status Activates, suspends, or closes a spend card. Closing is not reversible, so suspend a card you may want back.
List Card Transactions Lists a card's transaction history. One route serves both programs, taking either a spend card or a gift card identifier.
Create Gift Card Issues a gift card against a wallet and assigns it to a payee. One-time cards cannot be topped up later, so choose the rechargeable kind if you may add funds.
Get Gift Card Retrieves one gift card.
List Gift Cards Lists the gift cards on your account.
Recharge Gift Card Adds funds to a rechargeable gift card from its wallet.

Addresses, Categories, and Vouchers

List Custom From Addresses Lists the stored return addresses used when mailing checks and documents.
Get Custom From Address Retrieves one stored return address.
Create Custom From Address Stores a return address for check and document mailing, whose identifier the mailing routes take.
Update Custom From Address Updates a stored return address.
Delete Custom From Address Permanently removes a stored return address.
List Custom To Addresses Lists the stored recipient addresses used when mailing checks and documents.
Get Custom To Address Retrieves one stored recipient address.
Create Custom To Address Stores a recipient address for check and document mailing.
Update Custom To Address Updates a stored recipient address.
Delete Custom To Address Permanently removes a stored recipient address.
List Categories Lists the income and expense categories checks can be filed under.
Create Category Creates an income or expense category for filing checks.
Create Voucher Creates a remittance voucher, the itemized stub that prints with a check explaining what it pays for.
Get Voucher Retrieves one voucher with its line items.
Update Voucher Updates a voucher. The voucher items replace the stored list, so send every line you want to keep.
Delete Voucher Permanently deletes a voucher.

Document Mailing

Upload Document Uploads a document for mailing and returns its identifier. An idempotency key makes a retried upload return the same document rather than posting a second copy.
Upload HTML Template Uploads an HTML file as a reusable mailing template, which the template mailing route then fills with data.
Mail HTML Template Renders an uploaded HTML template with your data and posts the result to a payee. This is the mail-merge route: one template, one payee, one data object per letter.
Mail PDF Document Posts a PDF to an address, with the sender and recipient given inline. The state must be the two-letter code.
Add Sender Address Stores a sender address for document mailing.
Delete Sender Address Removes a stored sender address.
List Reply-To Addresses Lists the reply-to addresses available for document mailing, whose identifiers the template mailing route takes.
Track Mailed Document Returns the carrier and delivery state for a mailed document.

Webhooks

Verify Webhook Signature Checks a webhook delivery against your webhook secret using a constant-time compare. The signed value is the raw body text exactly as received, so re-serializing the parsed JSON changes the bytes and the check fails.

Frequently Asked Questions

What can FlowRunner do with OnlineCheckWriter?

FlowRunner agents can run List Bank Accounts, Get Bank Account, and Create Bank Account in OnlineCheckWriter, plus 141 more actions.

Does connecting OnlineCheckWriter to FlowRunner require OAuth?

No. OnlineCheckWriter connects to FlowRunner with an API key, no OAuth flow required.

Can OnlineCheckWriter trigger a FlowRunner workflow automatically?

OnlineCheckWriter doesn't currently expose triggers in FlowRunner. It connects as an action step inside workflows started by another trigger.

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