Hire senior TypeScript engineers in your time zone.

A senior TypeScript engineer's job is to make the type system actually protect the codebase, rather than being decoration around code that could just as easily be JavaScript.

Type architecture. They design the shared interfaces and types that model the domain accurately, including discriminated unions for state that can take multiple shapes, and generics for reusable, type-safe utilities and components.

End-to-end type safety. On full-stack projects, they keep frontend and backend types in sync, whether through a shared package, generated types from an API schema, or a framework like tRPC or GraphQL codegen that enforces the contract automatically.

Compiler configuration. tsconfig settings like strict mode, noImplicitAny, and module resolution decisions affect the entire team's daily experience. Senior engineers set these deliberately and know how to tighten them incrementally on an existing codebase without breaking the build.

Monorepo and build tooling. On projects with multiple packages, they manage how types are shared and versioned across the monorepo using tools like Turborepo or Nx, and keep build times reasonable as the codebase grows.

Migration leadership. Where the codebase started in plain JavaScript, senior engineers plan a realistic, incremental migration path, converting files gradually and enabling stricter compiler settings only once the codebase is ready.

TypeScript itself is just a compiler and type system. Real fluency comes from knowing how it interacts with the surrounding ecosystem.

Frontend frameworks. React, Angular, and Vue all have strong TypeScript support, but the idioms differ, from typing React props and hooks to Angular's decorator-based typing and Vue's script setup syntax.

Backend frameworks. NestJS builds TypeScript decorators and dependency injection into its core, while Express requires more manual typing effort. A strong hire should know which pattern fits your team's preferences.

Full-stack meta-frameworks. Next.js has become a common way to build full-stack TypeScript applications with shared types between server and client code in one project.

Type generation and validation. Tools like Zod, Prisma, and GraphQL codegen generate or validate types from schemas, reducing manual duplication between what the database, API, and frontend expect.

Tooling and quality. ESLint with TypeScript-aware rules, Prettier for formatting, and Jest or Vitest for typed testing round out a professional TypeScript setup.

Many candidates can write TypeScript that compiles without ever using the type system to actually prevent bugs. The interview should target that gap directly.

Give them a moderately complex data shape, such as an API response with several possible states, and ask them to model it with a discriminated union. Their solution reveals whether they reach for the type system's real power or default to broad, permissive types.

Ask how they decide when to use any versus unknown, and what they do when a third-party library has poor or missing types. This surfaces real experience versus textbook knowledge.

On full-stack roles, ask how they kept frontend and backend types in sync on a past project, whether through a shared package, code generation, or a framework like tRPC.

If the role involves a JavaScript migration, ask about their approach: which files they convert first, how they handle noImplicitAny during the transition, and how they avoid stalling feature work.

BetterEngineer already runs this kind of evaluation, covering type system depth, framework fluency, and migration experience, before you ever speak to a candidate.

Quick evaluation checklist:

• Ask candidates to type a moderately complex data structure using generics and utility types
• Review how they handle any versus unknown, and where they draw the line on strictness
• Check their experience keeping frontend and backend types in sync across a real project
• Probe their approach to migrating a JavaScript file or module to TypeScript incrementally
• Assess tsconfig and build tooling choices on a project they've owned