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Solutions

Engineering practices for organisations

Four areas of work, described in enough detail that you can tell before contacting us whether we are the right people. We publish no price list: scope drives cost, and quoting a number before understanding the problem would be guesswork.

Software Development

Custom Enterprise Software Engineering

We design, build and hand over custom software for organisations whose processes have outgrown off-the-shelf tooling. Work starts from your domain model and integration constraints, not from a template, and every engagement ends with the source, the deployment pipeline and the documentation in your possession.

What this includes

  • Multi-tenant SaaS platforms with role- and tenant-scoped authorisation
  • Service-oriented and microservice back ends with explicit contracts between services
  • Public and partner-facing APIs, versioned and documented as a deliverable
  • Event-driven and queue-backed processing for long-running or bursty workloads
  • Automated test suites and CI pipelines built alongside the application, not after it

Typical technologies

  • TypeScript
  • Python
  • PHP 8
  • React
  • Node.js
  • PostgreSQL
  • MySQL
  • Docker
  • REST
  • GraphQL

How it is engaged

Discovery and domain modelling, then iterative delivery in agreed increments, then handover of source, infrastructure definitions and documentation.

IT Consulting

Strategic IT & Cloud Architecture Consulting

We work with technical leadership on the decisions that are expensive to reverse: how a platform is partitioned, where state lives, what the migration order is, and how the result is going to be operated. Output is a written architecture with the trade-offs and rejected options recorded, and an implementation sequence your own team can execute.

What this includes

  • Target-state architecture with the trade-offs and the rejected alternatives written down
  • Cloud migration assessment and phased sequencing plans
  • Infrastructure-as-code foundations and environment parity
  • CI/CD, release and rollback design
  • Observability, capacity and cost-structure review of an existing estate

Typical technologies

  • AWS
  • Microsoft Azure
  • Google Cloud
  • Kubernetes
  • Terraform
  • Docker
  • CI/CD
  • Observability tooling

How it is engaged

Fixed-scope architecture review or an embedded advisory arrangement alongside your engineering team.

Security Engineering

Cybersecurity Integration & Systems Compliance

We integrate security controls into the software and infrastructure we build and review: authentication and authorisation models, secret handling, encryption in transit and at rest, dependency and supply-chain hygiene, and the logging that lets an incident actually be reconstructed. Where GDPR or a sector obligation applies, we build the technical measures and the evidence trail alongside the system.

What this includes

  • Identity, access and authorisation architecture across services
  • Secret management, key rotation and encryption design
  • Secure SDLC: dependency scanning, static analysis and review gates in CI
  • Audit logging and retention designed against a stated obligation
  • GDPR technical-measures implementation for systems that process personal data

Typical technologies

  • OAuth 2.0
  • OIDC
  • SAML
  • HashiCorp Vault
  • TLS
  • SAST/DAST tooling
  • SIEM integration
  • SBOM tooling

How it is engaged

Delivered inside an engineering or architecture engagement, or as a standalone review of a system you already run.

This is engineering work on your own systems under a written agreement. It is not a penetration-testing certification service, not a legal or regulatory opinion, and not incident-response retainer cover.

Software Development

Legacy System Modernisation & High-Load Optimisation

We take systems that are business-critical and change-hostile and make them tractable again: characterisation tests first, then incremental decomposition behind stable interfaces, so the business keeps running throughout. Where the constraint is throughput rather than maintainability, we profile the real bottleneck before changing anything.

What this includes

  • Codebase and dependency assessment with a risk-ordered modernisation plan
  • Incremental decomposition behind stable interfaces, without a big-bang rewrite
  • Database schema and query optimisation against measured query plans
  • Caching, queueing and read-path design for high-load systems
  • Characterisation test suites built before the first refactor

Typical technologies

  • Strangler-fig migration
  • PHP
  • Java
  • .NET
  • Python
  • SQL optimisation
  • Redis
  • Message queues
  • Load profiling

How it is engaged

Assessment phase first, delivered as a written plan you are free to execute yourselves; implementation only if you want us to do it.

Scope

Work we do not take on

So that there is no ambiguity about what this company sells, the following are outside our scope. We decline these enquiries rather than referring them on:

  • Consumer PC, phone or home-network repair, tune-ups or virus removal - we do not serve consumers at all
  • Technical support, help-desk or troubleshooting services for software or hardware published by third parties such as Microsoft, Apple, Google or any other vendor - we are not affiliated with, authorised by or acting for any of them
  • Password recovery, account unlocking or recovery of access to any account or device
  • Unsolicited contact claiming your device is infected, compromised or at risk - we never make such contact, and anyone doing so in this company's name is not us
  • Remote-access sessions to a private individual's personal computer
  • Search-engine ranking guarantees, ad-account management or lead-generation retainers
  • Legal, tax, accounting, financial, investment or medical advice of any kind

Platform and product names on this site (AWS, Microsoft Azure, Google Cloud, Kubernetes, PostgreSQL and others) identify the technologies our engineers build on. They are the trademarks of their respective owners. 3S holding OÜ is an independent software-engineering company and is not an agent, reseller, support provider or authorised representative of any of them, and this site does not offer support for their products.

Have a project that fits one of these?

Tell us the problem and the constraints. We will come back with an approach and the questions we still need answered.

Request Tech Proposal