Crellin Consulting

Software consultancy · London

Bespoke software, built to fit.

We design and build secure, scalable software around the way your business works.

What we do

Engineering, made to measure.

Full-stack development and delivery, from first conversation to production.

01 / 06

Custom software

Systems built around how your business works, from internal tools to customer-facing platforms.

  • Bespoke builds
  • Integrations
  • Automation

02 / 06

Web development

Fast, accessible, maintainable web applications, built full-stack.

  • Full-stack
  • APIs
  • Performance

03 / 06

Mobile development

Apps that feel native, work offline and share logic with the rest of your platform.

  • iOS & Android
  • Cross-platform

04 / 06

Cloud solutions

Infrastructure that scales with demand and costs what it should.

  • Architecture
  • Migration
  • CI/CD

05 / 06

Databases & data

Data models built for integrity and speed, with queries tuned to the questions you actually ask.

  • Schema design
  • SQL
  • Optimisation

06 / 06

Agile delivery

Hands-on project leadership that keeps scope honest and working software shipping.

  • Project management
  • Roadmapping

How we work

Measured twice. Built once.

  1. 01

    Measure

    We learn your operations, constraints and goals, so we solve the right problem.

  2. 02

    Pattern

    An architecture and plan cut to your requirements, and no bigger than they need to be.

  3. 03

    Build

    Short, visible iterations, so you see working software early and can steer.

  4. 04

    Fit

    We harden, document and hand over cleanly, with support as you grow.

Sebastian Crellin, founder of Crellin Consulting
Sebastian CrellinFounder

The founder

Senior engineering. Direct line.

Sebastian is a senior full-stack engineer who also leads delivery. The person scoping your project is the person who builds it.

He works across Python, Java, JavaScript and SQL, on web and mobile apps, cloud infrastructure and databases.

About us

Principles

Innovation, with precision.

  1. 01

    Tailored, not templated

    Designed for your context, with no off-the-peg compromises.

  2. 02

    Secure by default

    Designed in from day one, not bolted on before launch.

  3. 03

    Built to scale

    Architecture that grows with you, without a rebuild.

  4. 04

    Precision engineered

    Clean, tested, documented code your team can own.

Let's talk

Find your perfect fit.

Tell us what you need. We'll come back with a clear plan to build it.