Python APIs

Python development

From high-concurrency FastAPI services to data extraction and automation tooling, we build robust Python backends—with tests, strict typing, and observability.

Overview

How we approach Python development.

Python is where most of the work behind an AI or automation product actually lives: the API the front-end calls, the pipeline that moves and reshapes data, the workers that run long or scheduled jobs, and the integration layer that talks to everything else. We build all four, with the operational concerns treated as part of the deliverable rather than something to add later.

For APIs we default to FastAPI with Pydantic models at every boundary. Requests are validated before they reach business logic, responses are typed, and the OpenAPI schema is generated from the code rather than maintained separately, so the contract your front-end or your client integrates against is always the contract the service actually enforces.

Work that does not belong in a request cycle goes to a queue. Document parsing, model calls, third-party syncs, report generation, and scheduled jobs run as background tasks with explicit retry policies, idempotency keys, and dead-letter handling, so a transient failure in someone else's API does not corrupt your data or silently drop a job.

Every service ships with the things that make it operable: structured logging with request correlation, health and readiness endpoints, database migrations under version control, a test suite covering the paths that carry money or data, and a container image that runs the same way on a laptop and in production.

What We Deliver

  • FastAPI and Django backend APIs
  • ETL and data ingestion pipelines
  • AI and machine learning service integration
  • Unit tests, typing, and Dockerization
Delivery Methodology

How we build and deploy.

Structured engagement from initial process audit to live production monitoring.

01

Contract and data model first

We define the API contract and database schema before implementation, so integration work on both sides can start immediately and in parallel.

02

Core service implementation

Typed endpoints, business logic isolated from transport concerns, and migrations checked in alongside the code that needs them.

03

Asynchronous and scheduled work

Long-running and periodic jobs move to a queue with retries, idempotency, and dead-letter handling so failures are recoverable rather than silent.

04

Hardening and handover

Load testing against realistic traffic, structured logging and metrics, containerised deployment, and documentation an on-call engineer can follow.

Problems Solved

Operational challenges we eliminate.

The Bottleneck

A script that worked once is now business-critical infrastructure

Our Solution

We turn it into a real service: tests, typed interfaces, error handling, logging, scheduled execution, and a deployment path that does not depend on one person's machine.

The Bottleneck

Jobs fail silently and nobody notices until a customer does

Our Solution

We add structured logging, failure alerting, and a retry policy with dead-letter capture, so failed work is visible, diagnosable, and replayable.

The Bottleneck

The service falls over under concurrent load

Our Solution

We profile the actual bottleneck, which is usually connection handling or blocking calls in an async path, then fix it with pooling, caching, and moving heavy work to background workers.

Technical Depth

Under the hood.

Deep architectural rigor built for software engineers and technical decision-makers.

Validation at every boundary

Pydantic models validate inbound requests, outbound responses, and third-party payloads, so malformed data is rejected at the edge instead of corrupting state downstream.

Async where it pays

IO-bound work uses async endpoints and connection pooling to hold high concurrency on modest hardware; CPU-bound work is moved off the event loop rather than blocking it.

Idempotent background jobs

Queue tasks are safe to retry, with idempotency keys and exponential backoff, so a network blip does not produce a duplicate charge or a double-sent email.

Migrations and reproducible environments

Alembic migrations under version control and pinned, containerised dependencies mean the environment that passed tests is the environment that runs.

Common Use Cases

Where this applies.

Backend APIs for web and mobile clients

The service layer behind a product, with authentication, permissions, and a documented contract your front-end team can build against.

Data ingestion and ETL pipelines

Scheduled extraction from APIs, databases, and files, with transformation, validation, and loading into a warehouse or operational store.

AI and model serving backends

The service that sits between your application and a model provider: prompt construction, schema validation, caching, cost control, and fallback handling.

Automation and integration services

Middleware that connects systems which were never designed to talk to each other, with the retry and reconciliation logic that keeps them consistent.

Why Lesscode

Verified delivery standards.

85% faster

Underwriting Acceleration

Finject MCA brokerage CRM with AI statement parsing

98% compliance

Brand-Compliant Social Reach

PostAutoPilot distributed social automation platform

$300K+

Client Value Delivered

Over 200+ projects shipped across SaaS, AI, and workflow automation

100% IP

Intellectual Property Guarantee

Clients own 100% of all custom code, prompt pipelines, and databases upon launch

Frequently Asked Questions

Common questions about Python development.

Q.FastAPI or Django?

FastAPI for APIs, AI backends, and integration services, where typed contracts and async concurrency matter most. Django where you need its admin, ORM, and batteries-included ecosystem, typically for content-heavy or internally administered applications. We will tell you which one your project actually needs.

Q.Can you work on an existing Python codebase?

Yes. A large share of our Python work is stabilising code someone else wrote: adding tests around current behaviour, introducing typing incrementally, untangling blocking calls, and getting it deployable before changing features.

Q.How do you handle background and scheduled jobs?

Celery or RQ with Redis for most workloads, or a managed queue where the infrastructure already exists. Tasks are written to be idempotent, with retries, backoff, and dead-letter handling so failures are recoverable.

Q.Do you deploy it, or do we?

Either. We deliver a containerised service with CI configuration and deployment documentation. We can run the deployment to your cloud account, or hand it to your platform team to run themselves.

Selected Case Studies

Real software we have shipped.

New business / 2026

Have a process that should work better?

Bring us the bottleneck, the brittle build, or the idea. We'll give you a direct read on what to do next.