Seattle Software Agency SeattleSoftware Agency

API Development & Integration

We design and build APIs that connect your systems, power your products, and scale without breaking.

Every modern software product is really a collection of APIs talking to each other. Whether you need a public-facing API for partners, an internal API to connect microservices, or integrations with third-party platforms like Stripe, Salesforce, or Shopify, the quality of your API layer determines the quality of everything built on top of it.

At Scale Labs, we build APIs that are fast, well-documented, and designed for the real world — where traffic spikes happen, third-party services go down, and requirements change quarterly. We work with RESTful, GraphQL, and event-driven architectures depending on what your system actually needs, not what is trendiest.

We have helped companies across the US build API infrastructure that handles millions of requests per day with sub-100ms response times. From initial schema design through to rate limiting, authentication, and monitoring, we own the full lifecycle.

What You Get

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RESTful API Design

Resource-oriented APIs with proper HTTP semantics, versioning strategies, and consistent error handling that developers actually enjoy working with.

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GraphQL Implementation

Schema-first GraphQL APIs with DataLoader batching, persisted queries, and complexity analysis to prevent expensive operations from taking down your server.

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Third-Party Integration

Production-grade integrations with platforms like Stripe, Twilio, Salesforce, HubSpot, and Shopify — including retry logic, webhook verification, and idempotency.

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API Documentation

Auto-generated OpenAPI/Swagger docs, Postman collections, and developer guides that keep your API accessible and adoptable.

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Authentication & Security

OAuth 2.0, API key management, JWT tokens, rate limiting, and request signing — implemented correctly, not bolted on as an afterthought.

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Monitoring & Observability

Request tracing, latency percentiles, error rate dashboards, and alerting so you know when something is wrong before your users do.

Our Approach to API Design

Good API design starts with understanding who will consume the API and how. A mobile app hitting your API over cellular has very different needs than a backend service making server-to-server calls. We start every project by mapping out the consumers, their access patterns, and their performance expectations.

We follow contract-first design — the API schema is defined and agreed upon before implementation begins. This lets frontend and backend teams work in parallel, catches design problems early, and produces APIs that are consistent and predictable.

For REST APIs, we use OpenAPI 3.1 specifications. For GraphQL, we use SDL-first schema design with code generation. Both approaches produce machine-readable contracts that drive documentation, client generation, and testing automatically.

Integration Architecture That Handles Failure

Third-party integrations fail. Stripe has outages. Webhook deliveries get dropped. OAuth tokens expire at the worst possible moment. The difference between a fragile integration and a production-grade one is entirely about how you handle these failures.

We build integrations with circuit breakers, exponential backoff with jitter, dead letter queues for failed webhook processing, and idempotency keys to prevent duplicate operations. When a third-party service goes down, your system degrades gracefully instead of falling over.

For event-driven architectures, we implement reliable message processing with tools like BullMQ, Amazon SQS, or Google Cloud Pub/Sub — choosing the right tool based on your existing infrastructure and throughput requirements.

Performance and Reliability at Scale

API performance is not just about fast code — it is about smart caching, efficient database queries, and appropriate use of connection pooling. We implement multi-layer caching with Redis, CDN-level caching for public endpoints, and stale-while-revalidate patterns that keep response times low even under heavy load.

For high-throughput APIs, we design with horizontal scaling in mind from day one. Stateless services, distributed rate limiting with Redis, and database read replicas ensure your API can handle traffic spikes without architectural changes. Every API we build includes comprehensive testing: unit tests for business logic, integration tests against real databases, contract tests to catch breaking changes, and load tests with k6 to verify performance under pressure.

Technologies We Use

Node.jsTypeScriptExpressFastifyGraphQLPostgreSQLRedis

Frequently Asked Questions

Should I use REST or GraphQL for my API?
It depends on your consumers. REST is simpler, better cached, and widely understood — great for public APIs and server-to-server communication. GraphQL shines when you have multiple frontend clients (web, mobile, partner apps) that need different subsets of your data. We often use both in the same system, with REST for simple CRUD and GraphQL for complex data fetching.
How do you handle API versioning?
For REST APIs, we typically use URL-based versioning (e.g., /v1/users, /v2/users) because it is explicit and easy to route. For GraphQL, we use schema evolution — adding new fields without removing old ones, and using the @deprecated directive when fields are being phased out. Both approaches include deprecation timelines and migration documentation.
Can you integrate with our existing systems?
Yes. We regularly integrate with ERP systems, CRMs, payment processors, shipping providers, and custom internal tools. If it has an API (or even a database we can connect to), we can integrate with it. We also build custom middleware when direct integration is not feasible.
What does API development typically cost?
A focused API project — for example, building a partner-facing REST API on top of your existing database — typically runs $15,000 to $40,000 depending on the number of endpoints, authentication requirements, and integration complexity. Complex API platforms with multiple consumers and real-time features can be $40,000 to $80,000+.
How long does an API project take?
A focused REST API with 15-20 endpoints, authentication, and documentation takes 4-6 weeks. A more complex project with GraphQL, third-party integrations, webhooks, and real-time features typically takes 8-12 weeks. We deliver incrementally so you can start consuming the API before the full build is complete.

Need an API That Actually Scales?

Tell us about your integration challenges. We will design an API architecture that connects your systems reliably and performs under pressure.

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