Most JavaScript developers say they know TypeScript. Most of them mean they've worked in codebases where TypeScript was already set up and they wrote type annotations when the linter forced them to.
That's not the same as a developer who understands TypeScript's type system, uses it to make bugs impossible rather than just documented, and knows when to push back on type complexity that isn't worth the maintenance cost. When you hire TypeScript developers, the gap between these two skill levels is wide, and it shows up in production within the first sprint.
This guide covers what TypeScript proficiency actually looks like, what EU developers charge, how to screen candidates before the interview, and five questions that reveal real depth.
TypeScript developer proficiency: what it actually means
There are three levels worth distinguishing when you hire TypeScript developers:
Level 1 - Syntax-aware. The developer writes TypeScript but mostly uses any when things get complicated, doesn't use generics, and treats TypeScript as JavaScript with optional annotations. The code compiles. It isn't safer than JavaScript.
Level 2 - Type-aware. The developer uses interfaces, type aliases, union types, and generics correctly. They understand the difference between type and interface. They can read and extend existing TypeScript code confidently. Most developers who say they "know TypeScript" are at this level.
Level 3 - Type-system literate. The developer uses TypeScript's type system to eliminate entire classes of bugs. They understand conditional types, mapped types, and type inference. They can design type-safe APIs that catch errors at compile time. They also know when type complexity isn't worth the maintenance overhead and ship simpler solutions instead.
For most product teams, you need at least Level 2, and Level 3 for engineers building shared libraries, public APIs, or complex state management. The interview questions below help you identify which level you're actually hiring.
TypeScript developer rates in Europe
TypeScript is now the default for most modern JavaScript and Node.js work. That means TypeScript isn't a premium specialization the way it was in 2019. You're paying for JavaScript expertise with TypeScript fluency, not a separate category.
EU rates for senior TypeScript developers in 2026:
- Romania, Bulgaria, Hungary: €60-85/hr
- Poland, Czech Republic: €70-95/hr
- Portugal, Ukraine: €65-95/hr
- Netherlands, Germany, UK (local contract): €100-160/hr
For senior full-stack engineers strong in TypeScript on both frontend (React) and backend (Node.js, Nest.js), rates sit toward the upper end of each range. Backend-only TypeScript engineers typically run €5-10/hr below full-stack rates. EU nearshore networks consistently deliver better value for long-term embedded work than freelance platforms.
How to assess TypeScript developer skills before the interview
By the time you're running a technical interview, you've already spent sourcing time on each candidate. Pre-screening TypeScript proficiency saves everyone hours.
Code review as a filter. Send a small TypeScript code sample with deliberate problems: implicit any leaks, unsafe type assertions, missing discriminated unions, imprecise return types. Ask candidates to review and comment on it. A Level 1 developer runs the code as written. A Level 3 developer explains what's structurally unsafe and proposes a better design.
Short asynchronous coding task (15-20 minutes). A focused TypeScript exercise using generics and a realistic data structure filters Level 1 candidates quickly. A type-safe event emitter, a typed API response handler, or a basic mapped type utility works well. Keep it short enough that experienced developers aren't annoyed, long enough that it can't be completed without actually understanding generics.
GitHub or portfolio review. Look at TypeScript files in their public repositories. Are types precise or mostly any? Do they use generics? Are interfaces well-defined or loosely typed? Real code written under production pressure tells you more than any interview answer about how someone actually works.
5 interview questions for TypeScript developers
1. What's the difference between type and interface in TypeScript, and when do you prefer one?
Good answers cover the key technical differences: interfaces support declaration merging and can be extended with extends; type aliases handle union types, intersection types, and mapped types that interfaces can't. Better answers add a practical heuristic: "I use interfaces for object shapes I expect others to extend, and type aliases for everything else." Concerning answers conflate the two or give a rote response without a real preference.
2. How would you type a function that returns different output types depending on its input type?
This tests knowledge of function overloads and conditional types. At Level 2, acceptable answers use function overloads correctly with concrete types. At Level 3, candidates discuss conditional types and the infer keyword. The red flag: typing the return as any or using a single broad return type that loses the relationship between input and output.
3. You're building a state machine in TypeScript. How do you type it to make invalid transitions impossible at compile time?
Strong candidates use discriminated unions to model state and action types. They explain why switch on a discriminated union gives TypeScript enough information to narrow types correctly in each branch, eliminating entire categories of state bugs at compile time. Weaker candidates describe the implementation without connecting it to what TypeScript can and can't enforce.
4. When have you chosen NOT to add types to something, and why?
This is the judgment question. TypeScript proficiency includes knowing when complex types create maintenance overhead that outweighs the safety benefit. Good answers: "Test utilities where the types would just restate the implementation" or "Internal scripts with a short lifespan." Concerning answers: "I type everything always" (over-engineering risk) or "Whenever it gets hard" (under-engineering habit).
5. How do you handle external API responses that TypeScript can't guarantee at runtime?
This tests understanding of the gap between TypeScript's static analysis and runtime reality. Strong candidates know TypeScript types don't validate at runtime. They use Zod, io-ts, or a custom parse function with explicit validation at API boundaries. They understand that casting an API response directly to a TypeScript type is a false sense of safety. Weak answers: trusting TypeScript's types at the API boundary without any runtime validation.
Red flags when reviewing TypeScript candidates
Heavy use of any. Check TypeScript files in their code samples or public repos. Some legitimate uses exist (certain third-party library integrations, JSON.parse edge cases). Pervasive any use means TypeScript is decorative, not functional.
Type assertions everywhere. as SomeType silences TypeScript rather than satisfying it. Occasional use is fine. Frequent use means the types aren't designed correctly and the developer is working around the type system instead of with it.
No generics in a complex codebase. Senior TypeScript developers use generics. If their code copies logic for different concrete types rather than abstracting with generics, they're operating below senior level regardless of years of experience claimed.
"TypeScript slows me down." Some developers resent TypeScript's constraints and work around them. They'll call TypeScript "too strict" when the actual problem is their type design. This attitude compounds quickly in a shared codebase where other engineers depend on those types.
What to put in a TypeScript developer job description
"TypeScript experience required" tells candidates nothing. Include specifics:
- Frontend, backend, or full-stack (React, Node.js, Nest.js, etc.)
- Whether it's a greenfield TypeScript codebase or an ongoing migration from JavaScript
- Whether you run strict mode (this matters a lot to strong TypeScript developers)
- Whether they'll be writing shared library types or working in a product codebase
A job description that mentions "strict mode on a React + Nest.js codebase with Zod for API boundary validation" attracts experienced TypeScript engineers and filters candidates who can't match it. Generic descriptions attract generic candidates.
How HighCircl vets TypeScript developers
Our vetting uses peer code review by engineers, not recruiters or automated test platforms. TypeScript candidates complete a real code review exercise on a TypeScript codebase and a technical interview with a senior engineer who knows the stack. We're not running timed algorithm challenges. We're looking at how candidates reason about type design under realistic production constraints.
Senior TypeScript engineers on our EU network run €65-105/hr. Most have 5+ years specifically in TypeScript. We deliver a shortlist in 72 hours. No placement fees.
See how it works, or read our guides on how to hire React developers and how to hire Node.js developers for context on hiring in adjacent stacks.
Frequently asked questions
How much does a senior TypeScript developer cost in Europe?
Senior TypeScript developers in EU nearshore markets run €60-105/hr depending on country and seniority. Full-stack engineers (React + Node.js) sit at the upper end. Local rates in Germany or the Netherlands are €100-160/hr.
Is TypeScript harder to hire for than JavaScript?
Not significantly. TypeScript is the default in most modern JavaScript stacks, so most experienced JS developers have some exposure. The challenge is separating real depth from surface-level familiarity — which is what the vetting process is for.
Should I require strict mode in my job description?
Yes, if you use it. Strict mode is a meaningful signal — it tells experienced TypeScript engineers you take type safety seriously. Candidates who can't work in strict mode are typically at Level 1 or early Level 2 proficiency.
How long does it take to hire a senior TypeScript developer?
Through a nearshore network, 72 hours for a shortlist. Through direct hiring or generalist platforms, expect 4-8 weeks for a senior role with proper technical screening.
Can a strong JavaScript developer learn TypeScript on the job?
Getting to Level 2 (type-aware) is achievable in a few months. Level 3 (type-system literate) takes years of practice in real production codebases. If you need someone writing shared library types from day one, hire at that level rather than planning to develop it.
