OpenAPI-first design
We define API contracts in OpenAPI 3.0 before writing implementation code, enabling parallel frontend development, auto-generated client SDKs, and clear versioning contracts.
Custom API Development
Well-designed APIs are the backbone of modern software. We design and build custom REST and GraphQL APIs that are typed, documented, versioned, and built to handle the integrations, load, and security requirements of your specific product.
Type safety throughout
TypeScript on Node.js or Python with Pydantic, type safety from database model to API response, eliminating a class of runtime errors and simplifying maintenance.
Security baseline included
Authentication (JWT, OAuth 2.0), rate limiting, input validation, SQL injection prevention, and proper CORS configuration are baseline requirements, not optional additions.
A custom API is only as good as its documentation and reliability. We deliver APIs with OpenAPI 3.0 specifications, Swagger UI, automated test suites, and deployment configurations that enable confident integration by any consumer.
We choose REST or GraphQL based on your access patterns: REST for simple, resource-oriented APIs; GraphQL for complex data relationships, multiple clients with different data needs, or real-time subscriptions.
What this includes
- OpenAPI 3.0 specification (contract-first)
- RESTful or GraphQL API design
- JWT and OAuth 2.0 authentication
- Rate limiting and quota management
- Comprehensive error handling and status codes
- Automated test suite (unit and integration)
- API documentation (Swagger UI / Redoc)
Every engagement produces clear, documented deliverables. Here is exactly what is included in our custom api development service.
01OpenAPI 3.0 specification
02Production API implementation
03Authentication and authorisation layer
04Automated test suite
05API documentation (Swagger UI)
06Deployment configuration and CI/CD
APIs are OpenAPI-first — contracts reviewed before handlers — with versioning (/v1), rate limits, and problem+json error shapes. Auth uses OAuth2 client credentials or JWT with short-lived tokens; sensitive fields never appear in logs. Load tests on critical endpoints (checkout, search) establish p95 latency budgets before mobile clients integrate.
Frontend
Next.js App RouterReact 18+Tailwind CSSCore Web Vitals tuning
Backend & data
Node.js / Python APIsPostgreSQLRedis cachingREST & GraphQL
Operations
CI/CD pipelinesDocker / KubernetesObservabilitySecurity hardening
01
Architecture mapping
Dependencies, API contracts, compliance constraints, and performance budgets documented before sprint one.
02
Secure sprints
Two-week increments with GitHub access, demo recordings, and QA checkpoints, client visibility at every stage.
03
QA & handover
Automated tests on critical paths, security review, runbooks, and knowledge transfer to your team.
Manufacturing distributor
- Challenge
- Salesforce and NetSuite duplicated customer records.
- Simplileap solution
- Event-driven sync with mapping table and DLQ replay.
- Outcome
- Reconciliation effort down 87%.
Home goods wholesaler
- Challenge
- Magento migration needed B2B pricing, PO capture, and ERP sync.
- Simplileap solution
- Shopify Plus B2B, Checkout UI extensions, and webhook reconciliation.
- Outcome
- Order error rate 6% → 0.4%; ERP sync under five minutes p95.
Currency
Package
Ideal for
Investment
Includes
Package
Product MVP
Ideal for
Startups
Investment
₹8L – ₹25L
Includes
- Discovery
- Design + web/mobile + API
- CI/CD
- Launch support
Package
E-commerce build
Ideal for
Retail & D2C
Investment
₹80K – ₹15L
Includes
- Catalogue & checkout
- Payment integrations
- Admin dashboard
- Performance tuning
Package
Mobile app (iOS / Android)
Ideal for
Product teams
Investment
₹6L – ₹18L
Includes
- UX + React Native / native
- API integration
- App Store submission
- Up to 10 screens
Company and Service positioning is reviewed for production delivery standards by Harsha Parthasarathy (Co-Founder, Strategy & Operations 24+ years IT veteran, IBM, Global Delivery, Program Management) and Keshav Sharma (Co-Founder, Engineering and Lead Architect, Full-stack engineering, product delivery and technical standards).
- Verified entity
Simplileap Digital LLP
- Recognition
- LLPIN
AAU-8582
- Startup India
DIPP83124
- Founded
November 2020
- Office
Residency Rd, Bengaluru, India
Common questions about custom api development
REST is simpler, more cacheable, and well-understood. GraphQL is better when multiple clients need different data shapes, when data relationships are complex, or when real-time subscriptions are needed. We recommend based on your specific access patterns and team experience.
Both, API design is a core part of our engagement. We work with you to define resource models, endpoint structure, and data contracts before implementation. Good API design is far cheaper to get right at the design stage.
Ready to get started with custom api development?
Share your requirements with our team. We respond within one business day with a clear plan from discovery to delivery.
