TYPESCRIPT AGENCY FOR CODE THAT HOLDS
TypeScript makes visible which data is expected where – from the frontend to the API. We introduce it where it genuinely takes load off your team.
What is TypeScript?
TypeScript is JavaScript with types. The language is developed by Microsoft as open source and translated into plain JavaScript before it runs. In the process the compiler checks whether data and functions fit together and shows errors before users see them. nextlevels builds frontends, apps and backends in TypeScript throughout.
We areTypeScriptengineers
We use module boundaries, generics in moderation and strict tsconfig profiles – pragmatic instead of academic.
- Monorepo and package boundaries with shared types
- OpenAPI/zod integration for runtime and build-time safety
- Refactoring paths out of JavaScript legacy
- ESLint/Prettier and CI type gates
TypeScript or JavaScript?
TypeScript is not an end in itself. This is how we judge when the extra effort pays off:
| Situation | TypeScript pays off | JavaScript is enough |
|---|---|---|
| Size of the codebase | Several modules, still growing | A short script or a single widget |
| Team | Several developers, changing staff | One person, short lifespan |
| Interfaces | Frontend and backend share data models | None, or a single simple interface |
| Refactoring | Frequent; the compiler shows every affected place | Rare |
| Existing code | Convert step by step, file by file | Stays until the conversion pays off |
TypeScript 7 was released in July 2026. Microsoft ported the compiler to native code for it and calls it roughly ten times faster. Long waits for type checking are no longer an argument against TypeScript.
Static analysis as a safety net
The compiler catches whole classes of errors before users see them – especially with changing API versions.
Structural typing
TypeScript models JavaScript realistically: duck typing remains possible while critical spots are still protected.
DX & scaling
Autocomplete and navigation in large repos lower onboarding time – decisive for enterprise teams.
Interop with JS
Gradual adoption: new modules strictly typed, legacy fenced off until it amortises to replace.
API-first teams
DTOs as a single source of truth avoid drift between Swagger and UI models.
Large frontends
Design system props and page reducers get typed – refactors become predictable instead of roulette.
What we do for you with TypeScript
Bookable individually or as a project.
New builds
Web apps, mobile apps and APIs in TypeScript, with strict compiler settings from the start.
Migration from JavaScript
File by file, along the riskiest places. The application stays shippable while strictness increases in stages.
Shared types
One data model for frontend and backend, generated from OpenAPI or checked at runtime. When the interface changes, the compiler reports every affected place.
Upgrade to TypeScript 7
We check build tools and dependencies, switch over and measure build time before and after.
Type checks in the pipeline
No merge without a green compiler. Plus consistent rules for linting and formatting.
Code review and pairing
We look at your codebase and work with your team on the places where types are missing or bypassed today.
How a TypeScript project runs
Cost and duration depend on scope. Our project calculator gives you a first range; the binding figure comes with the offer after the workshop.
First call
You describe the goal, the users and the systems you already have. We tell you straight away whether TypeScript fits or whether another route is better.
Architecture workshop
We define the data model, interfaces and hosting and cut the scope into packages. The offer is based on that.
Delivery in iterations
We ship in short steps to a test environment, so you see every stage. Tests and code review are part of each step.
Go-live and operations
We deploy to your infrastructure or run the application for you. After that we handle updates and monitoring if you want.
Frequently asked questions about TypeScript
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When is it worth switching from JavaScript to TypeScript?
As soon as the codebase grows, several developers work on it or frontend and backend exchange data. For a short script it is not worth it.
Does TypeScript cost more than JavaScript?
A little more time at the start, because types have to be written. In return, errors show up during development instead of in production, and refactoring becomes plannable. TypeScript itself is open source under the Apache 2.0 licence and free.
How do you migrate a JavaScript codebase without stopping everything?
TypeScript runs alongside JavaScript. We convert file by file and raise the compiler's strictness in stages. Your team can keep shipping the whole time.
What does TypeScript 7 bring?
Microsoft ported the compiler to native code and calls it roughly ten times faster. For you that means shorter builds and faster feedback in the editor. According to Microsoft, some tooling, for example for Vue, Svelte or Astro, cannot use TypeScript 7 yet. We check that before an upgrade.
How do you make sure frontend and backend use the same data types?
We share types through a common package or generate them from the interface's OpenAPI description. Where data comes from outside, we also validate it at runtime.
How do you stop standards from eroding in daily work?
The type check runs in the pipeline; a merge with compiler errors is not possible. On top of that come pairing and short training sessions so your team carries the rules itself.
Your edge with TypeScript
Types are team communication. We prevent the "any" swamp and deliver patterns that both junior and senior devs can carry.
Fewer null-pointer surprises in integration code
Better IDE support and faster reviews
Clearer API contracts between frontend and backend
Sustainable tsconfig stages instead of big-bang migration
Read on and check
Legacy check
Six questions: how risky is your legacy system?
Reducing technical debt
Our service in detail.
Custom software development
When the migration becomes a project.
REST API
Where shared types help most.
Project calculator
A first cost range for your project.
Ready for your TypeScript project?
Let's talk about your requirements – we'll get back to you within 24 hours with concrete next steps.
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