TypeScript Development Company

What does a TypeScript development company actually deliver?

Usually one of three things. A new build: a React or Next.js front end and a Node.js API written in strict TypeScript from the first commit, with the types shared between them. A migration: an existing JavaScript codebase moved to TypeScript module by module while it stays in production. Or consulting: an audit of a TypeScript codebase that is not paying off - loose compiler settings, any leaking through the business logic, API data trusted without validation - with a written list of fixes.

At Miracuves all three end the same way: the repository, the tsconfig, the CI type-check and the documentation are handed over, and the IP is assigned to you from the start.

When is TypeScript the right choice, and when is it not?

TypeScript pays off when a codebase will live for years, when more than one developer works in it, or when the front end and back end must agree on the shape of data - SaaS products, admin dashboards, marketplaces, payment flows. The compiler turns a renamed field or a missing null check into a build error instead of a support ticket.

It adds little to a one-off script, a landing page with a few lines of JavaScript, or a prototype you plan to throw away. For model training and data pipelines, Python is the better tool; for low-level systems work, Rust or Go. We say which applies before we quote.

How do you migrate a JavaScript codebase to TypeScript?

Incrementally - no rewrite, no feature freeze. The TypeScript compiler can build .js and .ts files side by side, so the codebase moves across one area at a time:

• Add a tsconfig with allowJs, so existing JavaScript keeps building
• Type the edges first: API responses, database models and shared utilities
• Rename files to .ts or .tsx as each area is touched, typing as you go
• Turn on strict checks one flag at a time, starting with noImplicitAny and strictNullChecks
• Add a tsc --noEmit step to CI so the typed share of the code can only grow

Should the backend be written in TypeScript too?

Often, yes. Node.js runs the compiled output, and NestJS or Express let the API share its types with the React or Next.js front end through a common package or tRPC - change an endpoint and the front-end build fails at once, not in production. Zod supplies the runtime half: TypeScript types disappear at compile time, so request bodies, webhooks and third-party responses are parsed against a schema before the code trusts them.

A different backend language makes sense when the heavy work lives there - Python for machine learning, Go for very high-throughput services. Then we generate TypeScript types from the API's OpenAPI spec, so the front end is still checked against the real contract.

What does TypeScript cost to run and maintain?

The language is free and open source, and it adds nothing at runtime: it compiles to plain JavaScript, so hosting on Vercel, AWS or your own servers costs the same as an untyped app. The cost is paid at build time - a type-check step in CI - and in the discipline of writing types as the code is written.

The return shows up in maintenance. Upgrading a library, renaming a database column or changing an API response produces a list of compiler errors to work through, rather than bugs found by users weeks later. A new developer can read the types to learn how the data flows. On a product maintained for years, that is where TypeScript earns its keep.

Does TypeScript affect SEO or page speed?

Not directly. Browsers and search crawlers never see TypeScript; they receive the compiled JavaScript with the types stripped out. What decides rankings and Core Web Vitals is how pages are rendered and how much JavaScript ships. For search-facing pages we use Next.js server rendering or static generation, split code by route, and check each production build with Lighthouse.

TypeScript helps indirectly. Typed props, typed route parameters and typed content models make large refactors of a site safe, so performance work does not quietly break pages that already rank.

Should you hire TypeScript developers or work with an agency?

Hire in-house when TypeScript work is continuous and you can afford senior review - someone has to own the tsconfig, push back on any in pull requests and keep the shared types coherent as the product grows. Work with an agency when you need a first version fast, a migration done alongside your roadmap, or a second opinion on a codebase that has drifted.

The two combine well. Miracuves builds and hands over a documented, strictly typed codebase, and your first in-house hire can extend it from day one - the types tell them what every function expects. Ongoing work is also available on a monthly retainer from $2,299.