API Integration Cost Calculator
Every third-party service your software connects to adds real hours to the build. Pick the integrations you need and this calculator estimates the added cost, developer hours and timeline, plus a reminder of the ongoing usage fees each vendor charges on top.
How it works
Connecting your software to an outside service is never free plumbing. Each integration means reading the vendor's documentation, handling authentication, mapping data both ways, building error handling and retries, and testing edge cases like failed payments or rate limits. This calculator assigns a realistic build-hour estimate to each common integration, adds them up, and multiplies by your chosen developer rate.
The hour estimates reflect typical agency scope, a straightforward payments hookup lands lighter than a full ERP or inventory sync, which touches far more of your data model. The timeline assumes one developer working a standard 40-hour week, so it shows roughly how long the integration work alone would take in sequence.
One thing every buyer should budget for: the number below is a one-time build cost. Payments, SMS, mapping, AI and most other APIs also bill you every month based on usage, a percentage of each transaction, a fee per message, or a cost per API call. Those run separately from the development spend.
integration cost = (sum of integration hours) × developer rate · timeline weeks = ceil(total hours ÷ 40)
Integrations are usually one slice of a larger project. To scope the whole thing, use our software development cost calculator, or if you are still deciding whether to build at all, compare options with the build vs buy calculator.
FAQs
How much does it cost to integrate a third-party API?
Most well-documented APIs add somewhere between 30 and 120 hours of development work each. At a blended $70/hour rate that is roughly $2,000 to $8,000 per integration, with heavier systems like ERP or inventory syncs costing more. Enter your specific integrations above for a tailored estimate.
Are there ongoing costs after the integration is built?
Almost always. This tool estimates the one-time build cost only. Vendors like Stripe, Twilio and mapping providers charge recurring usage fees, a percentage per transaction, a fee per SMS, or a cost per API call, that continue for as long as you use the service. Factor those into your monthly operating budget separately.
Why do some integrations take so many more hours than others?
Complexity depends on how much of your system the integration touches. A payment or analytics hookup is fairly contained, while a CRM, ERP or inventory integration has to sync large amounts of data in both directions, stay consistent, and handle conflicts, which multiplies the build, testing and edge-case work involved.