We design and build SaaS platforms where the API contract comes first — OpenAPI-driven, versioned from day one, and built for the developer ecosystems your customers and partners depend on.
API Protocols, Standards & Tools We Build With — OpenAPI, REST, GraphQL, gRPC, AsyncAPI, Swagger, Postman, OAuth 2.0, JWT, API Gateway, Kong, Webhooks
Most SaaS platforms treat the API as an afterthought — an export layer bolted on after the product is built. The result is an inconsistent interface with no versioning strategy, documentation that lags the implementation, and breaking changes that hit integrators without warning. We build platforms the other way round.
In an API-first engagement, we design the OpenAPI or GraphQL schema before writing a line of implementation code. The schema becomes the contract between your platform and every consumer: your own frontend, your customers' integrations, and your partners' applications. Implementation then proves the contract rather than defining it.
The payoff is a platform that developer teams trust. Documentation that is always accurate. SDKs that can be generated automatically. Integration partners who can onboard self-serve. And a codebase where every feature is testable, mockable, and replaceable without touching the consumer interface.
API documentation written after the fact — always out of date
OpenAPI schema is the source of truth — docs are always accurate
Breaking changes pushed without versioning, hitting integrators immediately
Versioning strategy defined upfront — deprecated endpoints maintained safely
No schema validation — consumer errors surface in production
Schema validation at the gateway — invalid requests rejected before processing
Frontend and backend tightly coupled — parallel development blocked
Frontend teams develop against mock servers before the backend is built
Third-party integrations require custom, brittle adapters
Partners self-serve with generated SDKs and an interactive developer portal
The compounding cost of API-last architecture grows with every integration partner and every new platform feature. Retrofitting API-first practices into a mature codebase takes three to five times longer than building correctly from the start.
Seven specialist service lines, each built for a specific type of API platform challenge.
We map your product surface, identify every consumer — internal, partner, and customer — and design an API architecture that serves all of them. Versioning strategy, authentication model, rate limiting policy, and deprecation lifecycle are defined before implementation begins.
We build RESTful APIs that follow OpenAPI 3.0 specifications, with consistent resource naming, pagination, filtering, and error response formats. Every endpoint is documented, contract-tested, and deployed through a CI pipeline that catches breaking changes automatically.
We design schema-first GraphQL APIs with typed resolvers, query depth limits, persisted queries, and subscription support for real-time use cases. We implement DataLoader patterns to eliminate N+1 queries and federation for multi-service graph composition.
For high-throughput service-to-service communication, we implement gRPC with Protobuf schemas and bi-directional streaming. For event-driven integration we design AsyncAPI-specified message contracts over Kafka, RabbitMQ, or AWS EventBridge.
We configure and deploy API gateways — Kong, AWS API Gateway, or Apigee — handling OAuth 2.0 token verification, rate limiting, IP allowlisting, request transformation, and centralised logging. Security is applied at the gateway layer, not duplicated across services.
We build interactive developer portals with live OpenAPI documentation, sandbox environments, code samples in multiple languages, and webhook testing tools. A well-designed developer portal reduces integration support load and accelerates partner onboarding by orders of magnitude.
We connect your platform to third-party APIs — payment providers, identity services, ERPs, and data sources — handling authentication, rate limit management, retry logic, and data transformation. For existing platforms, we migrate undocumented APIs to OpenAPI-specified, versioned, gateway-managed interfaces.
A structured six-stage process from free scoping call to live API deployment and developer enablement.
We review your product roadmap, existing integrations, and consumer requirements. We define the scope of the API surface, identify breaking constraints, and design the initial resource model. This session is free and carries no obligation.
We write the OpenAPI or GraphQL schema — endpoint paths, request and response schemas, authentication flows, and error codes. The contract is reviewed and signed off before implementation begins, including by any integration partners who will consume the API.
We stand up a mock server from the OpenAPI spec so frontend teams and integration partners can develop against the API before the backend is built. We also build a thin prototype to validate the schema against real data and surface any design issues early.
We implement the API endpoints against the agreed contract, integrating with your databases, third-party services, and existing systems. Gateway configuration, authentication, rate limiting, and observability instrumentation are included from the first production deployment.
We run contract tests to verify the implementation matches the OpenAPI spec, load tests to validate throughput targets, and security reviews covering OWASP API Top 10. We establish baseline metrics and document all security controls for compliance evidence.
We deploy the API to your infrastructure, publish the developer portal, and generate SDKs in your target languages. We train your team on the versioning and deprecation process and hand over runbooks covering gateway operations, rate limit tuning, and incident response.
We review your product roadmap, existing integrations, and consumer requirements. We define the scope of the API surface, identify breaking constraints, and design the initial resource model. This session is free and carries no obligation.
We write the OpenAPI or GraphQL schema — endpoint paths, request and response schemas, authentication flows, and error codes. The contract is reviewed and signed off before implementation begins, including by any integration partners who will consume the API.
We stand up a mock server from the OpenAPI spec so frontend teams and integration partners can develop against the API before the backend is built. We also build a thin prototype to validate the schema against real data and surface any design issues early.
We implement the API endpoints against the agreed contract, integrating with your databases, third-party services, and existing systems. Gateway configuration, authentication, rate limiting, and observability instrumentation are included from the first production deployment.
We run contract tests to verify the implementation matches the OpenAPI spec, load tests to validate throughput targets, and security reviews covering OWASP API Top 10. We establish baseline metrics and document all security controls for compliance evidence.
We deploy the API to your infrastructure, publish the developer portal, and generate SDKs in your target languages. We train your team on the versioning and deprecation process and hand over runbooks covering gateway operations, rate limit tuning, and incident response.
Select an industry to see how we design API-first platforms that scale to enterprise demand.
API-first architecture is foundational for fintech platforms that must connect to payment networks, banking rails, and regulatory data providers while maintaining strict security and compliance.
API-first architecture is foundational for fintech platforms that must connect to payment networks, banking rails, and regulatory data providers while maintaining strict security and compliance.
Healthcare API platforms require FHIR compliance, HIPAA-safe data handling, and deep integration with EHR systems, device manufacturers, and payer networks.
Retail and e-commerce API platforms must handle catalogue complexity, high-concurrency order flows, and integration with logistics, payment, and fulfilment partners.
Logistics API platforms connect carriers, warehouse systems, customer portals, and IoT devices, requiring resilient integration patterns and real-time data flows.
HR platforms depend on API-first design to connect ATS, HRIS, payroll, and learning systems into a unified employee data layer that third-party partners can build on.
Media and content platforms use API-first design to power headless CMS delivery, content monetisation, and multi-channel distribution to web, mobile, and connected TV.
Perimattic's work resulted in stable production systems. The team was helpful, easily accessible, and communicative through email. Their professionalism was impressive.
Quality
4.5
Schedule
5.0
Cost
5.0
Willing to Refer
4.5
DevOps Managed Services · Oct 2023 – Aug 2024
24/7 monitoring and support for production environments plus Linux server administration for a leasing automation company.
The new architecture is scalable and highly efficient, saving a lot of money in fees. Perimattic provides high-quality IT consulting and cloud development work promptly and at great value. The team remains involved from the planning stage to providing support, showing diligence and proactiveness.
Quality
5.0
Schedule
5.0
Cost
4.5
Willing to Refer
5.0
AWS Migration (Legacy → Microservices) · Nov 2018 – Ongoing
Transitioned a travel systems company's legacy server system to an AWS-based microservices architecture with ongoing maintenance.
Four structural advantages that separate contract-first API engineering from ad-hoc integration work.
Every engagement starts with the schema, not the code. We write the OpenAPI or GraphQL contract, review it with your team and integration partners, and only then begin implementation. The contract is the authority — not the code, not the documentation generated from it.
We treat the developer experience of your API as a first-class product requirement. Interactive documentation, predictable error formats, consistent pagination, SDK generation, and sandbox environments are included by default — not added as afterthoughts.
OAuth 2.0, JWT validation, rate limiting, CORS policy, HTTPS enforcement, schema-level input validation, and secret management are applied to every API we build. We follow OWASP API Top 10 as a minimum baseline and conduct security reviews before every production deployment.
We select the right API gateway — Kong, AWS API Gateway, Apigee, or Traefik — based on your infrastructure and scale requirements, not our defaults. The same applies to backend frameworks: Node.js, Python/FastAPI, Go, and NestJS are all in active use across our API projects.
“The API contract is your platform's promise to every developer who builds on top of it. Breaking that promise without warning is the fastest way to lose integration partners. We design every API so that promise is one you can keep.”
API-first platform development is an approach where the API contract — the schema, endpoints, authentication model, and versioning strategy — is designed and agreed before any implementation begins. Every feature is built as an API endpoint first, and the user interface or consumer application is built on top of that contract. The result is a platform where every capability is programmatically accessible, documented, and testable from day one.
In code-first development, the API is generated from the implementation — the code is written first and the API documentation is extracted afterwards. In API-first development, the OpenAPI or GraphQL schema is the source of truth. It is written, reviewed, and validated before a single line of implementation code is written. API-first produces more consistent, stable, and developer-friendly interfaces because the contract drives the implementation rather than the reverse.
OpenAPI is a standard specification format for describing REST APIs — it defines endpoints, request and response schemas, authentication requirements, and error codes in a machine-readable YAML or JSON document. For SaaS platforms, OpenAPI matters because it generates interactive documentation automatically, powers mock servers for frontend teams to develop against before the backend is built, enables contract testing to catch breaking changes before deployment, and allows clients to generate typed SDKs in any language.
REST is the right choice for most SaaS platforms: it is well understood, easy to cache, and integrates straightforwardly with API gateways, CDNs, and third-party tooling. GraphQL is a strong fit when your consumers need flexible data fetching — mobile clients that want to minimise payload size, or developer platforms where third parties need to compose queries from a rich data graph. We recommend REST with OpenAPI as the default and introduce GraphQL selectively for use cases that genuinely benefit from it.
We implement URI versioning as the default approach — /api/v1/ and /api/v2/ — because it is explicit, easy to document, and straightforward to route at the gateway level. We design versioning strategy upfront, including what constitutes a breaking vs non-breaking change, how long deprecated versions are maintained, and how consumers are notified of deprecations. Our OpenAPI specs document version lifecycle so consumers always know what is stable, deprecated, and sunset.
Every API we build includes OAuth 2.0 or JWT-based authentication, HTTPS enforcement, rate limiting and throttling at the gateway layer, input validation against the OpenAPI schema, CORS policy configuration, and security headers. For internal service-to-service communication we use mutual TLS or API key authentication with IP allowlisting. Secrets are stored in managed secret stores such as AWS Secrets Manager or HashiCorp Vault, never in environment variables committed to version control.
An API gateway is a managed entry point that sits between your clients and your backend services. It handles cross-cutting concerns: authentication verification, rate limiting, request routing, SSL termination, logging, and — for some gateways — transformation. For most SaaS platforms with more than one service, an API gateway reduces duplicated logic and gives you centralised visibility into API traffic. We work with AWS API Gateway, Kong, and Apigee depending on your infrastructure and scale requirements.
An API strategy review and first endpoint design typically takes two to four weeks. A production API with authentication, versioning, documentation, and a developer portal typically takes six to twelve weeks depending on the number of endpoints and integration complexity. We provide a detailed estimate after a free scoping session where we review your existing systems and roadmap.
An API strategy and design engagement starts from around USD 8,000. A full production API build with gateway, auth, documentation, and SDK generation typically ranges from USD 25,000 to USD 80,000 depending on scope. Projects with significant legacy integration or compliance requirements sit at the higher end of the range. We scope every engagement before quoting.
Yes. We regularly take existing undocumented or inconsistently designed APIs and retrofit an OpenAPI specification, standardise naming conventions, introduce versioning, and add authentication where it is missing. The migration is typically phased: we document and stabilise existing endpoints first, then introduce a gateway layer, and finally refactor the underlying implementation over time. Consumer-facing behaviour is maintained throughout so there is no disruption to existing integrations.
Share your integration requirements and we will design an API contract that scales from your first integration partner to your thousandth. We scope every engagement with a free discovery session before any commitment.