--- title: "API Design & Integration Services | 10 US Tech" description: "API design and systems integration in Chicago: clean, versioned APIs and integrations that make your stack work as one system. Fixed scope. Get a quote." canonical: https://10ustech.com/services/api-integration --- # We connect the systems you already run. Most businesses have plenty of software. The trouble is that the pieces don’t talk to each other. We design APIs that are documented and versioned, and we build the integrations that turn separate tools into one system of record. **Scope and price are fixed up front. You own everything at handoff.** ## Why integration matters Re-keyed orders and a spreadsheet bridging two platforms are the usual signs. So is a “sync” that silently dropped records last March. That kind of integration debt stays invisible until it costs you a customer or an audit. Done right, integration is plumbing you never think about. Data flows once and every system agrees. When something fails, it tells you. Our integration work runs on a few fixed rules. Idempotency means a retried request can never double an order or a charge. Explicit failure paths mean a downstream outage degrades gracefully without corrupting your data. Observability means that when something breaks at 1 AM, the alert says what broke and where. None of this is an enterprise luxury. It’s what makes an integration trustworthy at any size. We run this in production, where payments, POS, SMS and delivery providers all meet in one order flow ([the commerce systems we operate daily](https://10ustech.com/services/ecommerce-pos)). When an external provider fails mid-transaction on our platform, the customer is refunded automatically. That is what an honest integration failure path looks like. ## What’s included ### API design & build REST or GraphQL APIs with versioning, authentication, rate limiting and documentation a new developer can use the same day. ### Third-party integration We wire together payments, POS, messaging, logistics, CRMs and ERPs, and we test against how each provider really behaves. The docs are only a starting point. ### Webhooks & event flows Event delivery with signature verification and retries. Anything that still fails lands in dead-letter handling, so nothing drops silently. ### Data synchronization One source of truth across systems. Conflict rules and reconciliation checks catch drift before your customers do. ### Legacy connectivity Safe API layers over systems too old to change and too critical to replace. You modernize without a rewrite. ### Integration observability Health checks and alerting on every seam, with logging behind them. Your monitoring should find a failure before a customer does. ## How we work - **Map the data first.** Every flow is diagrammed and approved before code: source of truth, direction, transformation and failure mode. Ambiguity at this stage is where data gets lost. - **Test the provider’s real behavior.** We test every third-party API against its real responses and limits, including the edge cases. Gaps in the documentation are normal. - **Design the failure path with the happy path.** Retries, idempotency keys, reconciliation and alerts ship with the integration on day one. - **The digital handoff.** API code, documentation, provider credentials in your accounts, and runbooks transfer to you. You own and understand every seam in your stack. Related: [cloud & DevOps](https://10ustech.com/services/cloud-devops) · [e-commerce & POS systems](https://10ustech.com/services/ecommerce-pos). Based in Chicago? See [software development in Chicago](https://10ustech.com/software-development-chicago). ## Proof Live in production ### One order flow, many providers Payments, POS, SMS and delivery dispatch meet in a single order pipeline on a platform we run in production. When a provider fails mid-flow, the refund is automatic. [E-commerce and POS systems](https://10ustech.com/services/ecommerce-pos) Client, multi-state ### Quantum Prosthetics & Orthotics One platform serving six clinics across three states. Data consistency is a requirement there. [Quantum case study](https://10ustech.com/work/quantum-prosthetics-orthotics) ## Common questions **Can you connect systems that were never meant to talk?** Almost always, yes. Between official APIs, file exchange, database-level access, and carefully built adapters over legacy software, there is nearly always a safe path. The honest constraint is usually data quality, not connectivity — and we tell you which before the project starts. **REST or GraphQL?** REST is our default for public and partner APIs — it is simple, cacheable, and universally understood. GraphQL earns its place when many clients need flexible views of the same data. It is an engineering decision we make with you in writing, not a fashion statement. **How do you prevent an integration from silently failing?** By assuming it will fail and designing for it: idempotent operations, verified webhooks with retries and dead-letter queues, reconciliation checks that compare systems on a schedule, and alerts that reach a human. Silent failure is a design choice — we choose loud. **Can you replace our manual data entry between systems?** That is the most common integration project we do: orders, invoices, customer records, or inventory re-keyed between platforms. The SOW names the hours saved, and the reconciliation checks prove the automated flow is more accurate than the manual one it replaced. **Do we own the API and the integrations afterward?** Yes. The code, the documentation, the provider accounts and credentials — all in your name, all handed over with runbooks. Integrations are the connective tissue of your business; they should never be a vendor’s hostage.