First, decide what "connected" should mean
The connection is rarely the hard part. Deciding what should happen when a record changes is. Before choosing a method, write the three or four sentences you actually want:
- When a deal closes in the CRM, create the customer and the first invoice in QuickBooks.
- When an invoice is paid, mark the deal paid and stop any follow-up.
- When an invoice is thirty days late, send a reminder in our voice from the account owner, and tell them in Slack.
- Once a week, put total outstanding and the five oldest invoices in front of whoever runs the money.
Each sentence tells you which method you need.
Method one: the native integration
HubSpot's QuickBooks Online integration and Salesforce's QuickBooks connector both sync customers, products and invoices, and both let you create an invoice from a deal. If your four sentences are "keep the customer and invoice records matched," this is the answer, it costs nothing beyond the subscriptions you already pay, and it takes an afternoon.
What it will not do: act. It syncs records; it does not chase anyone, decide anything, or talk to Slack.
Method two: a workflow tool
n8n, Make and Zapier all carry QuickBooks and every mainstream CRM. A workflow watches for an event (invoice past due), applies a rule, and does something across systems (draft the reminder, log the touch, post to Slack). This is where the third and fourth sentences above live. The QuickBooks-to-CRM pairing is one of the most common templates on every platform for exactly this reason.
What it costs: the tool's subscription, and either your afternoon per workflow or $400 to $1,200 for someone to build and test one.
What to watch: the rule has to be written plainly, and someone has to own it when the CRM changes a field name. Workflows do not maintain themselves.
Method three: a built connection
When the rule needs judgment ("chase this one gently, that one firmly, and never the account we are mid-negotiation with") or touches the inbox, the calendar and the document store as well, a built system is the honest answer. It is also the one that shows up in the numbers: automated receivables cut days sales outstanding by 15 to 33 days in Chaser's and Billtrust's customer data, and 99% of the finance teams Billtrust surveyed reduced DSO after automating.
The workflow that pays first
Start with the overdue invoice. It has the hardest dollars behind it, it needs both systems, and it is small enough to be running in a week. It is one of the eight we build most, and the free file on the marketplace will be a working version of it.