How Much Does API Integration Cost for a Small Business?

“How much will integration cost?” is the right question. The honest answer depends less on lines of code than on how messy your truth sources are.

What moves the number

• Number of systems and direction of sync
• Data cleanup before anything can flow reliably
• Auth complexity—OAuth, rotating tokens, multi-tenant portals
• Error handling requirements—silent failure is not acceptable in finance or fulfillment
• Historical backfill vs forward-only events

Realistic first milestones

A focused two-system path—like HubSpot deal approved → QuickBooks invoice draft, or Stripe payment → internal fulfillment queue—often lands between $2k–$20k for a production-ready first slice.

When Zapier is cheaper—and when it is not

Zapier wins on simple, low-volume flows. Custom integration wins when mappings are non-obvious, retries matter, and someone needs to answer “why is this customer duplicated?” at 4pm on a Friday.