The three cost bands
One-way pushes (website form to CRM, orders to email, jobs feed to site) sit around £2,000 to £6,000 when both systems have documented APIs. Two-way synchronisation with logic (stock levels driving availability, CRM stages driving site content, account pricing) runs £6,000 to £20,000. Systems work against legacy software, government schemes or migrations starts above £20,000 and is priced after technical discovery, not before.
Our software and AI engagements start at £18,000 because most client integration work lands in the second and third bands once the real requirements surface. Smaller first-band connections are scoped individually.
What actually drives the price
The API itself is usually the cheap part. Cost concentrates in four places: edge cases (what happens when stock is negative, a record conflicts, a payment half-completes), data quality in the existing systems, authentication and security review cycles, and who owns failures in production.
A worked example from our own products: LoadSnap integrates with DEFRA's Digital Waste Tracking. The government API is documented; the engineering effort went into compliance workflows, failure handling for offline operators and the audit trail. That pattern, where the integration is 20% of the work and the operational reality is 80%, repeats everywhere.
Questions that scope an integration honestly
Answer these before asking anyone for a price, and the quotes you receive will actually be comparable.
- Which direction does data flow, and how fresh must it be (real-time, hourly, daily)?
- What should happen when either system is down or returns garbage?
- Who fixes a failed sync at 9am Monday, and how do they find out?
- Is there historical data to migrate, and who owns its quality?
- What changes in the business process once this works?
Why we price after discovery
Fixed quotes from feature lists are fiction in integration work. We run a short technical discovery against your actual systems, then itemise the build, which is why the number we give is one we keep. The same studio that designs your site builds the integration, so there is one accountable scope rather than an agency blaming a dev shop.
Written by Callum Wells, founder of Web Hero, a Leeds B2B web design and software studio. Published 18 March 2026.