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03Services

Backend, APIs and integrations

What users never see decides whether an app flies or stutters. We design and build backend systems that process millions of records, respond in milliseconds and hold up when traffic grows.

  • Python
  • FastAPI
  • PostgreSQL
  • WebSocket
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01What you get

What you get

  • 01

    APIs

    Fast, documented REST and WebSocket APIs in FastAPI.

  • 02

    Data pipelines

    Collecting, cleaning and normalising data from external sources — Cjenko processes price lists from 21 chains every day.

  • 03

    Real-time sync

    WebSocket sessions where a change reaches every device instantly — as in Songware.

  • 04

    Performance optimisation

    Profiling, indexes and better algorithms: Cjenko’s basket optimisation went from 3,300 to 16 ms.

  • 05

    AI integrations

    Practical AI — such as reading chord charts from photos in Songware.

  • 06

    Cloud and DevOps

    Docker, CI/CD, monitoring and scaling on DigitalOcean.

02Process

Four steps to your app

  1. 1. Discovery and plan

    We talk about goals, users and constraints. The result is a specification with priorities, an estimate and a delivery plan.

    • Workshop
    • Specification
    • Estimate

  2. 2. Design and prototype

    We test the interface and user flows on a clickable prototype before the first line of code.

    • UX flows
    • Design system
    • Prototype

  3. 3. Iterative development

    We ship in short cycles, with automated tests and continuous integration. You see progress regularly, not just at the end.

    • Iterations
    • Tests
    • CI/CD

  4. 4. Launch and growth

    Store release, error and performance monitoring, new versions. Launch is the beginning, not the end.

    • Release
    • Monitoring
    • Maintenance

03Technology

  • Python
  • FastAPI
  • SQLModel
  • PostgreSQL
  • PostGIS
  • Alembic
  • WebSocket
  • Docker
  • DigitalOcean
  • GitHub Actions

04From our workshop

From our workshop

Mobile app · Price comparison

Cjenko

Compare product prices and whole baskets at stores that suit you. Barcode scanning, shopping plans and price-drop tracking come together in a simple mobile app.

Case study →

Cross-platform app · Music

Songware

Live sets keep the whole band in sync, while set presentations put lyrics on an external TV or projector for the audience. Repertoire, setlists, recordings and conversations come together in the same app.

Case study →

05Questions

Questions

Why Python and FastAPI?

FastAPI is fast, modern and well documented, and Python has the richest ecosystem for data and AI work. Together with PostgreSQL it is a stable foundation for systems that grow.

Can you connect to our existing system?

Yes. Integrations with external APIs, databases and file formats are part of almost every project we do — from price lists in CSV, XML and XLSX to music formats such as MusicXML.

How do you handle large amounts of data?

With careful data modelling, indexes and measurement. Cjenko keeps more than 15 million price records, and its key calculations take milliseconds.

Who looks after the servers?

We can take on the whole lifecycle: hosting, monitoring, security updates and scaling. We run our own products on DigitalOcean, in Docker containers with automated deployments.

4sourceContact

Got an idea? Let’s build it.

Tell us briefly what you are building — or just the problem you want solved. We will get back with questions and a suggested next step.

Write to us

Write to us