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Software we build, and what you get when it ships

4Tuna OÜ writes business software to a written specification and hands over the source, the tests, the migrations and the pipeline. The engagements below are the three build-side disciplines; the advisory work is described separately.

Full-Stack & APIs

Custom Enterprise Programming

We design and write line-of-business software for organisations that have outgrown off-the-shelf tooling. Work starts from a signed statement of work and a written architecture note, proceeds in reviewable increments, and ends with source code, migrations, tests and operating documentation handed to your team.

Capabilities

  • Domain modelling and API contract design (REST, GraphQL, event-driven)
  • Back-end services in PHP, Node.js, Python, Go and Java
  • Front-end applications in React and TypeScript
  • Relational and document data modelling, reporting and integration layers
  • Third-party and legacy system integration against documented interfaces

What is delivered

  • Written technical specification and architecture decision records
  • Application and service source code in your own repository
  • Automated test suite and continuous integration pipeline
  • Database schema with reversible migrations
  • Runbook and handover session for your operations team

Engagement model. Fixed-scope statement of work, or a dedicated engineering team on a rolling monthly agreement.

Platform Engineering

Cloud Infrastructure & DevOps

We build the platform your applications run on and the pipeline that puts them there. Infrastructure is expressed as code and kept in your repository, so environments can be rebuilt from scratch rather than remembered. Where personal data is in scope we design the hosting region and processing chain around your GDPR obligations from the start.

Capabilities

  • Container orchestration and service deployment topology
  • CI/CD pipeline design across common hosted runners
  • Infrastructure as code with Terraform and configuration management
  • Observability stacks, structured logging and incident runbooks
  • EU-region hosting design and data residency planning

What is delivered

  • Infrastructure as code for every environment
  • Continuous integration and deployment pipelines with rollback
  • Monitoring, logging and alerting with documented thresholds
  • Backup and restore procedure, tested rather than assumed
  • Cost and capacity baseline for the running platform

Engagement model. Project engagement, optionally followed by an agreed support window.

Migration & Decomposition

Legacy Modernisation & Microservices

Older systems are rarely replaced in one step and rarely should be. We map what the system actually does, put a test and monitoring net around it, then move capability outwards in slices while the business keeps running. Each slice is independently reversible, so the programme can be paused at any point without leaving the estate in a broken half-state.

Capabilities

  • Monolith assessment and domain boundary identification
  • Strangler-fig and branch-by-abstraction migration strategies
  • Data migration with reconciliation and rollback
  • Service extraction, contract testing and API versioning
  • Runtime and framework upgrades on long-lived codebases

What is delivered

  • Behaviour map and dependency inventory of the existing system
  • Characterisation tests covering current behaviour before any change
  • Strangler-pattern migration plan, slice by slice
  • Extracted services with their own data ownership and contracts
  • Decommissioning plan for the parts finally retired

Engagement model. Phased programme, each phase separately scoped and independently reversible.

Plan the envelope

Size the work before you write the brief

The estimator below runs the same model our API does. Adjust the parameters, then send them with a request for proposal so the first conversation starts from something concrete.

Interactive planning tool

Architecture & project envelope estimator

What are we building
Expected scale
Data in scope
Availability target
Existing estate
How we would work together
3
012
Effort

306

251–392 person-days

Duration

12w

10–15 weeks

Team

6

people at peak

Phases

5

delivery stages

Recommended pattern

Service-oriented

The integration surface and availability target justify separating the parts that change or scale at different rates, while keeping the service count low enough that one team can still operate the estate.

  • Three to six deployable services
  • Database per service where ownership demands it
  • Synchronous API gateway
  • Shared observability and tracing layer

Effort by phase (person-days)

Architecture pressure

Indicative team shape at peak

  • 1× Solution architect
  • 3× Software engineer
  • 1× Platform / DevOps engineer
  • 1× Test engineer
  • Delivered in reviewable increments against a signed statement of work.
  • Adds a data-protection workstream: lawful basis mapping, retention design, data subject request handling and a record of processing activities.

This is not a quotation. This estimator is an indicative planning aid produced from the parameters you selected. It reports engineering effort, elapsed duration and team shape. It is not a quotation, an offer or a commitment, and it deliberately contains no monetary figures: 4Tuna OÜ issues fees only in a written proposal after reviewing an actual request for proposal. Real figures depend on requirements, existing systems and constraints that no on-page calculator can see.

Send these parameters with an RFPHow an advisory engagement runs

What we do not do

4Tuna OÜ works with organisations under a written agreement. We do not provide consumer or home-user technical support, we do not troubleshoot personal devices remotely, we do not recover passwords or accounts for individuals, we do not resell third-party software licences, and we do not repair hardware. We are an independent engineering company and are not affiliated with, and do not act on behalf of, any software or hardware vendor. If you need support for a product you bought, contact that product’s own vendor.

Request an RFP reviewTechnologies we work in