Hire TypeScript developers

Almost anyone who writes JavaScript will tell you they know TypeScript. The difference shows up months later, when the codebase is either a set of types that catch real bugs at compile time or a pile of any annotations that gives you the ceremony of types with none of the safety. A strong TypeScript developer produces the first kind, and it changes how fast the whole team can move: refactors become routine, new hires read the types instead of asking around, and a whole class of production errors never ships. turnkey.dev vets for that.

What a TypeScript developer does for you

A strong TypeScript hire will:

• Keep the codebase honest. Strict mode on, any treated as a bug, and types that model your domain so the compiler catches mistakes before your users do.
• Work across the stack. The same language runs your React front end and your Node back end, so one developer can own a feature end to end, sharing types between client and server instead of duplicating them.
• Make APIs type-safe. With tools like tRPC and Zod, the contract between front end and back end is checked at build time, and payload validation at the edges stops malformed data at the door.
• Set up tooling that pays for itself. ESLint rules that enforce the team’s standards automatically, Vite for fast builds, and CI that fails on type errors instead of letting them ship.
• Test what matters. Unit tests with Vitest, end to end flows with Playwright, and enough coverage that the team can deploy without holding its breath.
• Keep a monorepo workable. Shared packages, consistent configs, and build caching, so multiple apps and libraries live together without stepping on each other.

What type-system depth actually looks like

TypeScript’s type system is unusually powerful, and depth in it is measurable. A few markers that separate real fluency from resume TypeScript:

Types at the boundaries. The compiler can only trust what enters the system. Strong developers validate external data (API responses, form input, environment variables, queue messages) with a runtime schema like Zod, then let inferred types flow from there. Weak ones cast with as and hope, which is how “typed” codebases still crash on bad payloads.

Inference over annotation. Good TypeScript is not more annotations, it is fewer, placed where they anchor the design: function signatures, public APIs, domain types. If every local variable carries a written type, the developer is fighting the language.

Modeling states that cannot be wrong. Discriminated unions to make invalid states unrepresentable, narrowing instead of casting, unknown instead of any at entry points, branded types where two strings must never be confused (a UserId is not an OrderId). This is the part of the job that removes entire bug categories.

Generics with restraint. Generics, conditional types, and mapped types earn their keep in library and API-layer code. A senior knows when a clever type helps callers and when it becomes a puzzle the next developer cannot modify. Type-level cleverness for its own sake is a junior signal wearing a senior costume.

Compiler and build literacy. Knowing what tsconfig strictness flags actually do, why declaration builds slow down in a monorepo, and how to read a five-line type error and find the one word that matters.

Migrating from JavaScript

Migration is one of the most common reasons teams hire TypeScript help, and the difference between a good and bad migration is the plan, not the typing speed. The approach that works in practice runs incrementally: enable allowJs and compile the existing code untouched, convert files along the seams the team is already working in, keep strictness low at first and ratchet it up (noImplicitAny, then full strict) as coverage grows, and add CI checks so converted files never regress. Types for third-party libraries and the messy edges of the old code soak up more time than anyone expects; budget for that. A candidate who proposes a freeze-and-rewrite is proposing the version of this project that fails.

Where TypeScript pays off, and where it is optional

The payoff scales with codebase size, team size, and lifespan. TypeScript earns its cost when several people touch the same code, when the project will live for years, when front end and back end need a shared contract, or when refactoring fear has visibly slowed the team. It is genuinely optional for small scripts, throwaway prototypes, and single-developer tools, and a senior will say so rather than apply it everywhere on principle. If your need is really framework depth rather than language depth, the React, Angular, or Vue hubs below may be the better starting point, and the talent pools overlap heavily.

Senior signals to look for

• They ask to see your tsconfig early. The strictness flags tell them more about the codebase’s real state than any demo.
• They can describe a migration or a large refactor they ran, including what they sequenced first and what they deliberately left untyped.
• They talk about validation at runtime, not just types at compile time, and can say where the boundary between the two sits in their last project.
• Their instinct for generics is “as simple as callers allow,” and they can give an example of a type they simplified.
• They treat any escapes as debt with a plan, not as a style choice.

The common hiring mistake is testing TypeScript with syntax trivia. Anyone can learn what keyof does in an afternoon. Put candidates in a realistic strict-mode codebase with a refactor to make and a subtle type hole to find; fluency shows within the hour.

How turnkey.dev vetting works

Every developer goes through a screen on fundamentals (the type system, generics, narrowing, how TypeScript actually compiles), a practical exercise built around a realistic strict-mode codebase with a refactor and a bug to find, and a review of production TypeScript they have owned, including migrations run, tooling decisions made, and how their types held up as the code grew. Framework familiarity is noted, but we vet the language and engineering judgment underneath it. We reject far more than we accept.

Seniority, and what each level is for

Most companies coming to us need one senior developer who can own a product surface end to end, with a lead brought in briefly for decisions like monorepo structure or a large migration plan.

Engagement models

• Full time for continuous product work where the developer owns a surface of the codebase.
• Part time for migrations, type-safety cleanups, and maintenance of stable apps. A migration in particular works well as a part time senior engagement running alongside your team’s normal feature work.
• Fixed project for bounded outcomes: a strict-mode migration with a defined endpoint, standing up a typed API layer, or restructuring a monorepo.

What it costs, honestly

Vetted TypeScript developers typically bill in the $60 to $120 per hour range, with senior full-stack engineers at the top. Rates track seniority and region across the market, so treat the band as typical rather than fixed. Because TypeScript spans front end and back end, one strong hire often covers ground that would otherwise take two. You will see the rate before committing, and requesting a shortlist is free. Expect a shortlist in 2 to 5 days.

For comparison: Toptal-style vetted networks run at generally higher effective rates for a similar promise, marketplaces like Upwork are cheaper per hour but unvetted, and the resume-keyword problem is worse for TypeScript than most skills because every JavaScript developer can claim it. In-house hiring remains the right call for a long-lived core team; it just takes weeks to months you may not have when a migration is blocking everything behind it.

Start with a request, not a contract

Tell us your stack, the goal (a new build, a feature push, a strict-mode migration, or ongoing maintenance), and your timeline. We come back with a short list of vetted developers who fit, including rate and availability. You interview, run a paid trial if you want, and only then decide. If the fit is wrong in the first two weeks, we re-match at no cost.