API Integration Services That Keep Working After Launch Day
Connecting two pieces of software takes an afternoon. Keeping them connected takes design: what happens when one side is down, when the same record arrives twice, when someone edits it in both places at once, and when the vendor changes their API.
We connect CRMs, accounting, payments, ecommerce and booking systems, and build the sync logic, retries and alerts that keep the data trustworthy. This page is about connecting existing systems; if you need your own API built for others to use, that is API development.
This is for you if
- ✓Two systems that should share data do not, and someone fills the gap by hand
- ✓An integration you rely on breaks quietly every few weeks
- ✓Your store, CRM and accounting each hold a different version of the customer
- ✓A partner wants your data in their system and you need to send it safely
This is probably not for you if
- ✕A native integration or a Zapier template already does exactly this — use it
We would rather tell you now than take the project and disappoint you.
Worth knowing: Two-way sync is where most integrations go wrong. When both systems can edit the same record, you need a rule for who wins, decided before the build. "Last edit wins" sounds fair and quietly destroys data; deciding which system owns each field is usually the answer.
What you get
Sync design
Which system owns each field, how often data moves, and what happens on conflict, written down and agreed first.
Webhooks and polling done right
Events received, verified and processed once, with polling as a safety net for the ones that never arrive.
Duplicate protection
Idempotency keys and stored external IDs, so retries and repeated events never create duplicate customers or charges.
Rate limits respected
Queued requests and backoff, so large syncs finish instead of being throttled halfway.
Monitoring and alerts
Failed syncs reported with the record and the reason, plus a daily check that both sides still agree.
Backfill and migration
Historical data moved across once and checked, then kept in sync from then on.
Systems we connect
- CRM — HubSpot, Salesforce, Pipedrive and Zoho: contacts, deals and activity kept in step with your website and other tools.
- Accounting — QuickBooks Online and Xero: invoices, payments and customers created automatically, with tax and currency handled.
- Payments — Stripe and PayPal: payments, subscriptions, refunds and payouts reflected in every system that needs to know.
- Ecommerce — Shopify and WooCommerce: orders, stock and customers synced with fulfilment, accounting and marketing tools.
- Messaging — Twilio, email providers and Slack: messages sent and logged when something happens elsewhere.
- Maps and data — Google Maps, address validation and enrichment APIs, called sparingly to keep usage costs down.
What we build it with
Deliberately mainstream choices. You should be able to hand this to any competent developer later without them needing to learn something exotic first.
Front end
Next.js, React, TypeScript, Tailwind CSS
Back end
Node.js, Next.js API routes, Cloudflare Workers
Database
Postgres, Supabase, Cloudflare D1 and KV
CMS
Sanity, Payload, headless WordPress, or plain Markdown
Payments
Stripe, Shopify, WooCommerce
AI
OpenAI, Anthropic, and open models where they fit better
Hosting
Vercel, Cloudflare Pages — in your account, not ours
Analytics
Plausible, Fathom, GA4, Search Console
Not sure whether an integration is what you actually need? Send over what you are trying to fix and we will tell you straight — including if a smaller job would do it.
Ask us first →How it works
Read the docs
Both APIs reviewed for limits, authentication and the awkward cases before we quote.
Agree the sync rules
Field ownership, frequency and conflict handling written down and signed off.
Build and test
Tested against sandbox accounts and real data, including outages and duplicate events.
Monitor after launch
Alerting from day one, so a broken sync is noticed by us, not by a customer.
Work you can check
Real work that uses the same skills. Every card links to something you can open and inspect yourself.
Players Towel
A Next.js store with a towel designer. Every order reaches Shopify as a draft order through the Admin API, with live carrier shipping rates.
Product, built and launchedCrewCalculator
Thirteen building-trade calculators that draw every result to scale and check it against building code.
Questions
How much do API integration services cost?
Integrations between two well-documented systems start at $1,800 and usually land between $1,800 and $4,000. Two-way syncs with conflict rules, large backfills or poorly documented APIs cost more. The quote is fixed once we have read both APIs' documentation.
Zapier or a custom integration?
Zapier for simple one-way flows at modest volume. Custom when you need two-way sync, high volume, complex mapping, or reliability you can monitor. We will tell you which one your case needs, including when the answer is Zapier.
What if the vendor changes their API?
Vendors usually version their APIs and announce breaking changes months ahead. We pin versions and our monitoring catches anything that slips through. On a support plan, we also watch deprecation notices for the systems we connected and update before they break.
Can you integrate a system that has no API?
Sometimes, through scheduled file exports, a database connection, or screen automation as a last resort. Each is more fragile than an API, and we will say how fragile before you decide.
Do you build custom APIs too?
Yes. When you need to expose your own data to partners, apps or customers through an API you control, that is our API development service.
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