API & BackendEngineering
The frontend is what users see. The backend is what makes it work. We build the APIs, databases, and services that power your applications.
AIQSO Backend Engineering builds production APIs with FastAPI, Node.js, and PostgreSQL using microservice architecture, automated documentation, and deployment pipelines for scalable, maintainable backend systems.
Key Takeaways
- •FastAPI for Python-based services with automatic OpenAPI documentation and async request handling
- •Node.js with Fastify for high-throughput webhook receivers, real-time services, and JavaScript-native APIs
- •PostgreSQL with migrations, full-text search, and connection pooling for reliable data persistence
- •Every API ships with JWT auth, rate limiting, input validation, structured logging, and health checks
- •Deployed on Docker containers with CI/CD pipelines for zero-downtime updates
Backend Technology Stack
We choose tools based on the problem, not the trend. FastAPI excels at data processing and AI integration. Node.js handles real-time events and webhook orchestration. PostgreSQL provides the reliability that production data demands.
FastAPI (Python)
Our primary framework for data-intensive APIs. FastAPI generates OpenAPI documentation from type hints, handles async requests natively, and integrates directly with Python ML libraries, Pandas, and LLM SDKs. We use it for AI services, data processing pipelines, document parsing, and analytics endpoints. Pydantic models validate every request and response.
Node.js / Fastify
For APIs that need to handle high volumes of webhooks, real-time WebSocket connections, or JavaScript-native integrations. Fastify is our Node.js framework of choice for its schema-based validation, plugin architecture, and performance benchmarks. We use it for webhook receivers, notification services, and APIs that pair with Next.js frontends.
PostgreSQL
Our default database for structured data. PostgreSQL handles relational queries, full-text search, JSON columns, and transactional integrity. We use Prisma or SQLAlchemy for migrations and query building depending on the application language. Connection pooling via PgBouncer keeps performance consistent under load.
Redis & Celery
Redis serves as our caching layer, session store, and message broker. Celery handles background task processing for long-running operations like report generation, batch email sending, document processing, and scheduled jobs. Together they keep API response times fast while heavy processing runs asynchronously.
API Patterns We Build
Every business application has a backend, whether it is visible or not. These are the patterns we implement most frequently.
REST APIs for Web & Mobile
Versioned REST APIs with consistent response formats, pagination, filtering, and error handling. These serve as the backbone for Next.js frontends, Flutter mobile apps, and third-party integrations. Every endpoint is documented in OpenAPI spec and testable through Swagger UI.
Webhook Receivers & Event Processing
APIs that receive events from Stripe, GitHub, Twilio, CRM systems, and other services. Each webhook endpoint validates signatures, processes payloads idempotently, and dispatches downstream actions through n8n workflows or direct API calls. Failed deliveries retry automatically.
Authentication & Authorization Services
JWT-based authentication with refresh tokens, OAuth2 social login, role-based access control, and API key management. User sessions, permissions, and audit logs are handled by dedicated auth middleware that integrates with any frontend framework.
Data Processing Pipelines
APIs that ingest, transform, and output data in batch or streaming modes. CSV imports, PDF generation, report compilation, and ETL workflows run as background Celery tasks with progress tracking and result storage in PostgreSQL or Redis.
Production-Grade Standards
Every API we ship meets these standards before it reaches production. These are not optional extras.
Input Validation
Pydantic models or JSON Schema validate every request body, query parameter, and path variable before business logic executes.
Error Handling
Structured error responses with consistent formats, appropriate HTTP status codes, and actionable error messages for API consumers.
Rate Limiting
Per-endpoint and per-user rate limits prevent abuse and ensure fair resource allocation across API consumers.
Structured Logging
JSON-formatted logs with request IDs, response times, user context, and error traces for debugging and monitoring.
Health Checks
Dedicated endpoints that verify database connectivity, cache availability, and external service status for load balancers and monitoring.
CI/CD Pipeline
Automated testing, linting, and deployment through GitHub Actions with zero-downtime container restarts on Proxmox or Docker hosts.
Related Services
Web & Mobile Engineering
Full-stack engineering for production applications across web and mobile platforms.
Next.js Development
Server-rendered frontends that consume the APIs and backend services we build.
DevOps & Infrastructure
Docker, CI/CD, and Proxmox infrastructure where your backend services run.
Is This Right for You?
✓ When to Use This Service
- Ifyou need an API to power a web app, mobile app, or third-party integration — we build documented REST APIs with authentication and monitoring included
- Ifyour application needs background processing for heavy tasks — Celery and Redis handle async jobs while your API stays responsive
- Ifyou need to integrate AI models into your business logic — FastAPI integrates natively with Python ML libraries and LLM SDKs
- Ifyou want to own your backend infrastructure — we deploy on your servers or ours with full code ownership
✗ When This May Not Be the Right Fit
- Ifyou only need a static website with no dynamic data — a Next.js static export with no backend may be sufficient
- Ifyour entire application fits within a SaaS platform like Airtable or Notion — avoid custom backend development if off-the-shelf tools meet your needs
- Ifyou need a backend but have no frontend plan yet — design the user experience first so the API serves actual user needs