Pick the TypeScript problem. See who we would send.
Diego HernándezStaff Engineer95/ 100
Ananya ReddySenior Full-Stack92/ 100
Matías FernándezBackend Engineer88/ 10025,000 applied. 1,000 got in.
Five scored stages, all finished before a profile reaches you. Nobody skips a stage to hit a deadline.
From £15 an hour. That is the whole pricing page.
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£8,314/ monthEquivalent to £48 an hourWhat a TypeScript engineer does
TypeScript engineers build and maintain JavaScript applications with a static type system that catches design mistakes before runtime. In a modern stack, TypeScript sits across the frontend, backend, test suite, build tooling, and shared API contracts: React or Next.js on the client, Node.js services with Fastify, NestJS, or Express, database layers such as Prisma, and runtime validation with tools like Zod. In 2026, strong teams expect TypeScript 5.x fluency, strict compiler settings, ESM awareness, and clean integration with Vite, tsx, Vitest, Playwright, ESLint, and package managers like pnpm. A mid-level TypeScript engineer can type components, services, and API responses correctly. A senior engineer designs type-safe boundaries, simplifies complex generics, controls build performance, chooses when not to over-type, and prevents mismatches between compile-time types and runtime data. They make the codebase easier for the whole team to change safely.
Typical responsibilities
- Design, build, and maintain TypeScript applications across frontend, backend, and shared packages using strict compiler settings.
- Create type-safe API contracts between clients and services, including request validation, response typing, and error modeling.
- Refactor JavaScript or loosely typed TypeScript into maintainable modules without blocking product delivery.
- Own tsconfig, build, lint, and test setup using tools such as tsc, Vite, tsx, Vitest, Playwright, ESLint, and pnpm workspaces.
- Review pull requests for type safety, runtime safety, readability, performance, and appropriate use of generics and utility types.
- Debug production issues where TypeScript types, bundled JavaScript, Node.js behavior, or third-party package declarations do not match reality.
Must-have skills
- Strong command of TypeScript 5.x, including narrowing, discriminated unions, generics, conditional types, mapped types, template literal types, and the satisfies operator.
- Practical experience with strict mode and stricter options such as noUncheckedIndexedAccess, exactOptionalPropertyTypes, noImplicitOverride, and isolatedModules or isolatedDeclarations where appropriate.
- Production experience with Node.js and modern ESM/CJS package behavior, including moduleResolution, package exports, tsx or ts-node alternatives, and build output debugging.
- Ability to design runtime-safe boundaries using validation libraries such as Zod, Valibot, or io-ts instead of trusting compile-time types for external data.
- Frontend or full-stack experience with React, Next.js, Vite, or similar tooling, including typed hooks, server/client boundaries, and API data handling.
- Testing experience with Vitest or Jest plus Playwright or similar end-to-end tooling, with typed test helpers and reliable CI usage.
- Clear code review habits: spotting over-complex types, unsafe assertions, any leakage, brittle declaration files, and maintainability risks.
Nice to have
- Experience with monorepos using pnpm workspaces, Turborepo, Nx, or TypeScript project references.
- Experience building typed SDKs, internal packages, public libraries, or declaration files for JavaScript consumers.
- Familiarity with typed database access through Prisma, Drizzle, Kysely, or generated OpenAPI/GraphQL clients.
- Experience migrating large JavaScript or older TypeScript codebases to stricter compiler settings incrementally.
- Knowledge of performance and bundle analysis for TypeScript-heavy React, Next.js, or Node.js applications.
8 TypeScript interview questions that reveal real depth
These are the kinds of questions our engineers use in technical interviews. Each comes with what a strong answer sounds like.
Full set: 25 TypeScript questions by level, with red flags- Q1
How would you design a type-safe API boundary between a React client and a Node.js service?
Strong answer: A strong candidate separates compile-time types from runtime validation. They mention schema validation with Zod, Valibot, OpenAPI, GraphQL, or tRPC, and explain how request and response types are derived rather than duplicated. They also discuss typed error shapes, versioning, handling unknown external data, and keeping client code resilient when the backend evolves.
- Q2
When would you use a discriminated union instead of optional fields on one large interface?
Strong answer: A strong candidate explains that discriminated unions model mutually exclusive states clearly, while optional fields can allow impossible combinations. They describe using a stable tag such as status or kind, exhaustive switch checks with never, and safer UI or service logic. They should also know when a simple interface is enough and avoid unnecessary type machinery.
- Q3
What TypeScript strict options do you usually enable, and what tradeoffs do they create?
Strong answer: A strong answer starts with strict and discusses noUncheckedIndexedAccess, exactOptionalPropertyTypes, noImplicitOverride, noImplicitReturns, and isolatedModules or isolatedDeclarations. The candidate explains the safety gained and the migration cost. They should mention incremental adoption, fixing hot paths first, and avoiding broad any or non-null assertions just to silence the compiler.
- Q4
How do you decide whether a complex generic type is worth it?
Strong answer: A senior answer focuses on maintainability. The candidate weighs whether the type prevents real bugs, improves API ergonomics, and remains understandable to teammates. They may use constrained generics, overloads, helper types, or simpler explicit types. They should recognize red flags: slow editor performance, unreadable conditional types, and types that encode business rules better handled at runtime.
- Q5
A third-party package has incorrect or incomplete TypeScript types. What do you do?
Strong answer: A strong candidate first verifies whether the runtime behavior or the local usage is misunderstood. Then they consider updating the package, checking bundled declarations, adding a local declaration patch, using module augmentation, or contributing upstream. They avoid blanket any, isolate unsafe code behind a typed wrapper, and add tests to confirm the actual runtime contract.
- Q6
What problems can appear when moving a TypeScript Node.js project to ESM?
Strong answer: A strong answer covers package.json type, tsconfig module and moduleResolution, file extensions in emitted imports, CommonJS interop, default imports, __dirname replacements, test runner behavior, and package exports. The candidate should also mention checking generated JavaScript, not only types, because code can type-check but fail under Node.js module loading rules.
- Q7
How would you migrate a large JavaScript codebase to TypeScript without stopping feature work?
Strong answer: A strong candidate proposes an incremental plan: allowJs and checkJs where useful, add TypeScript to new code first, define tsconfig baselines, convert stable modules, type public boundaries, and track any usage. They prioritize high-change and high-risk areas, avoid massive rewrites, and use CI to prevent regressions while gradually tightening compiler options.
- Q8
How do you prevent TypeScript types from giving a false sense of safety?
Strong answer: A strong answer states that TypeScript types disappear at runtime. The candidate mentions validating external inputs, database results, environment variables, feature flags, and JSON parsing. They also discuss avoiding unsafe assertions, keeping generated types in sync, testing important contracts, and using unknown at trust boundaries until data is parsed and narrowed.
Senior TypeScript engineer job description
A ready-to-paste template. Or skip the posting entirely: send it to us as your brief and get a scored shortlist in 48 hours.
About the role We are hiring a Senior TypeScript Engineer to build and improve production software across frontend, backend, and shared packages. You will work with TypeScript 5.x, Node.js, modern React or similar UI tooling, and a strict, testable codebase. What you'll do Design type-safe features from API boundary to user interface. Build and maintain Node.js services, frontend modules, and shared libraries. Improve tsconfig, linting, testing, build, and CI workflows. Refactor loosely typed or legacy code without slowing delivery. Use runtime validation for external data, not just compile-time types. Review code for correctness, simplicity, and maintainability. Help the team make good decisions about generics, module structure, and package boundaries. What you'll bring Strong production experience with TypeScript and JavaScript. Good judgment with strict mode, generics, unions, narrowing, and utility types. Experience with tools such as Vite, tsx, Vitest, Playwright, ESLint, pnpm, or similar. Working knowledge of Node.js ESM/CJS behavior and modern package management. Clear communication in code reviews, technical design, and remote collaboration.
What you get with TypeScript
Pre-Vetted Expertise
Every TypeScript developer on OctogleHire passes a rigorous vetting process covering technical skills, communication, and problem-solving ability.
Start in Days, Not Months
Skip the lengthy recruitment cycle. Our TypeScript engineers are ready to integrate with your team and start delivering within days.
Up to 60% Cost Savings
Access world-class TypeScript talent at a fraction of the cost of local hires, without compromising on quality or experience.
Risk-Free Trial Period
Every TypeScript engagement starts with a trial period. If you're not completely satisfied, you pay nothing.
The engagement, as a spec sheet
How OctogleHire compares
Vetting
Resume screening only
Self-reported skills
5-stage technical vetting (1 in 25 pass rate)
Time to Hire
6–12 weeks
Weeks of filtering
48 hours to first match
Cost
$20K–$40K placement fees
Low rates, variable quality
40–60% less, no placement fee
Compliance
You manage it
You manage it
Fully managed (30+ countries)
Replacement
30–90 days (if any)
None
14–30 day replacement guarantee
Support
Account rep (9-5)
Ticket system
Dedicated account manager
“We in need of a handful of developers for our internal CRM build after speaking with multiple agencies and receiving some quotations we sat down with Yaseen from Octogle and we were pleasantly surprised to see what was available for us within their talent pool. we took on three developers saving upwards of circa £6000 per month and developing the software in record time exactly how we wanted it. Highly suggest anyone to use octogle hire if you’re looking for a cost-effective high-quality software development solution.”
Questions engineering leaders ask
Hire a TypeScript developer when the codebase needs safer change, clearer contracts, and better long-term maintainability. JavaScript skill is still essential because TypeScript emits JavaScript and runs on the same platforms. The difference is that a TypeScript specialist can design types that guide developers, catch integration mistakes early, and avoid unsafe patterns such as broad any, unchecked assertions, and duplicated API models.
Test practical type design, not trivia. Ask candidates to model real domain states, type an API response, validate unknown input, and refactor unsafe code. Include tsconfig judgment, strict mode experience, generic constraints, discriminated unions, and runtime validation. For senior roles, add questions about ESM/CJS, build tooling, monorepos, code review decisions, and when simpler explicit types are better than clever abstractions.
Productivity depends on codebase clarity, onboarding, test coverage, and domain complexity. A strong TypeScript engineer can usually make small fixes quickly, but deeper productivity requires understanding API boundaries, compiler settings, release flow, and team conventions. You can shorten ramp-up by documenting tsconfig decisions, package structure, local setup, testing commands, and examples of preferred patterns for errors, validation, and data fetching.
Use a freelance TypeScript developer for a defined project, migration, audit, integration, or temporary capacity need. Hire full-time when the person will own architecture, product knowledge, code review standards, and long-term maintenance. TypeScript quality compounds over time, so if the work involves core platform decisions, shared libraries, or ongoing API design, continuity is often more important than short-term task completion.
Yes, if they have real full-stack experience and understand that frontend and backend TypeScript have different risks. On the frontend, state, rendering, accessibility, and API data handling matter. On the backend, Node.js runtime behavior, validation, persistence, errors, and observability matter. A strong full-stack TypeScript engineer can share contracts without assuming compile-time types replace runtime checks.
Look for TypeScript 5.x experience and comfort with strict compiler settings. Common tools include tsc, tsx, Vite, Vitest, Playwright, ESLint, pnpm, and framework-specific tooling such as Next.js or NestJS. Candidates should understand modern Node.js, ESM/CJS differences, package exports, generated types, and runtime validation libraries. Exact tool names matter less than their ability to explain tradeoffs and debug the build.
A common mistake is treating TypeScript as just annotated JavaScript. Another is overvaluing complex type puzzles while ignoring runtime behavior, testing, and maintainability. Watch for candidates who use any too freely, trust external JSON without validation, or create types nobody else can understand. Strong engineers make unsafe areas visible, keep public contracts clear, and know when simple code is the safer choice.
Effective remote TypeScript engineers communicate through small pull requests, clear type and API decisions, written design notes, and predictable handoffs. They document assumptions in code, tests, and schemas rather than relying on meetings. For distributed teams, it helps to standardize formatting, linting, type-check commands, branch workflow, and code review expectations so feedback is about design and correctness, not local setup.
You'll receive 3–5 vetted candidate profiles within 48 hours of your demo call. Most companies go from first intro to signed contract in under 5 business days — compared to 6–12 weeks with traditional agencies.
Every developer passes a 5-stage process: application screening, stack-specific technical assessment, live system design interview, soft-skills evaluation, and reference checks. From over 25,000 applicants reviewed, only 1,000 have been accepted into our network.
OctogleHire engineers start at £15/hr (about $19), with senior engineers at about £24/hr. That is roughly 50–65% less than the loaded cost of an equivalent in-house hire in the UK, US or Australia — a senior UK hire costs about £48/hr once employer costs are included. There are no upfront fees or placement commissions; you pay one published hourly rate once your engineer starts.
Every placement includes a risk-free replacement guarantee — 14 days on our On-Demand plan and 30 days on our Marketplace plan. If a developer doesn't meet your expectations, we'll find a replacement at no additional cost and manage the transition for you. Our replacement rate is under 6%.
Send the brief. Meet TypeScript engineers on Thursday.
Twenty minutes with an Octogle engineer, then three to five scored profiles inside 48 hours. Free to post, with a replacement guarantee on every placement.