Why do businesses insist on TypeScript for new web apps?
Because it moves a large share of bugs from production to the developer's editor. TypeScript adds types to JavaScript, and the compiler checks that every function receives and returns what it promises before the code ever runs.
For a business owner, three benefits matter more than the technical detail. First, safer change: when a developer renames a field or changes an API, the compiler lists every place that breaks, instead of a customer finding one of them. Second, cheaper handover: types act as documentation that cannot go out of date, so a new developer understands the shape of your data in hours rather than weeks. Third, better tools: editors can autocomplete, rename and navigate code reliably, which makes every later feature a little quicker.
TypeScript is not a guarantee. Types disappear when the code runs, so data arriving from a form, an API or a database still needs checking at runtime. And a developer can switch the checks off with a few keystrokes. That is why, when you hire a TypeScript developer, you should look at how they use the language, not just whether their files end in .ts.
What does “strict mode” mean, and why should you require it?
Strict mode is the compiler setting that turns TypeScript's main safety checks on. The TypeScript documentation describes the strict flag as enabling the whole “strict mode family” of options, including noImplicitAny, strictNullChecks, strictFunctionTypes, strictBindCallApply, strictPropertyInitialization, noImplicitThis, useUnknownInCatchVariables and alwaysStrict.
Without it, TypeScript quietly lets through the two mistakes that cause most real bugs: values that might be null or undefined, and values whose type the compiler cannot work out (it silently treats them as any). A codebase with strict off can look typed and still crash on the same errors plain JavaScript does.
The same documentation lists two further options that strict does not switch on but that many careful teams add: noUncheckedIndexedAccess, which treats a lookup like prices[id] as possibly undefined, and exactOptionalPropertyTypes, which stops an optional field being set to undefined by accident. We enable the first on new projects and discuss the second case by case.
When you hire a TypeScript developer, ask to see the tsconfig.json from a recent project. It takes ten seconds and tells you more than an hour of interview.
How to evaluate a TypeScript developer from their code
Read a pull request they wrote, or have a developer you trust read it, and look for how they handle the places where types meet the real world. The signals below separate someone who uses TypeScript from someone who works around it.
Good signs
Discriminated unions for states such as loading, success and error; exhaustive switch statements that fail to compile when a new case is added; unknown instead of any for untrusted data; runtime parsing of API and form input; types derived from schemas rather than written twice.
Warning signs
Frequent any, casts with “as” to silence errors, non-null assertions (the ! operator) sprinkled everywhere, @ts-ignore comments without explanation, and interfaces that duplicate the database by hand and drift from it.
Structure
Types live next to the code that owns them, shared types sit in one place, and nothing exports a type called Data or Item that means five different things.
Our general web developer hiring guide covers contracts and staged payments; this section is the TypeScript-specific layer on top.
TypeScript interview questions that reveal real skill
Ask questions that need judgement, not memory. Anyone can look up syntax; you want to know how the candidate thinks when types and reality disagree.
- An API sometimes returns a user and sometimes an error object. How would you type and handle it?
- When would you use unknown instead of any, and what do you do next with an unknown value?
- How do you make sure form data sent to your API is really the shape your types claim?
- Show a situation where you would use a generic, and one where a generic would be over-engineering.
- What does the compiler do with types at runtime, and what follows from that?
- You inherit a codebase with 300 type errors after turning strict on. What is your plan?
- How do you share types between a React front end and a Node back end?
Good answers mention runtime validation, narrowing with type guards, incremental strictness and shared schemas. Watch out for answers that treat “as” casts as the normal fix for an error.
A paid half-day task helps too: give the candidate a small JavaScript module from your real code and ask them to convert it with strict on, adding validation at its inputs. The diff shows their habits clearly.
Converting a JavaScript codebase to TypeScript: how it works
Convert gradually, file by file, while the app keeps shipping. A big-bang rewrite stalls feature work for weeks and usually introduces new bugs; an incremental conversion does not.
The usual path: add TypeScript and a tsconfig with allowJs so JavaScript and TypeScript files live side by side; turn on checkJs or add JSDoc types to find the worst problems in existing files without renaming them; then rename files to .ts one area at a time, starting with shared utilities and data models, because everything else depends on them. Tests and a CI type check run on every change so progress never slides back.
Strictness rises in steps. We often start with strict off for converted files, fix every error, then switch on strictNullChecks, fix, then noImplicitAny, fix, then full strict. Each step is a separate pull request you can review. The conversion is finished when strict is on for the whole project and escape hatches are rare and commented.
Cost depends on size and tidiness: a well-structured 20-file Express API is a small job; a sprawling front end with untyped third-party libraries takes longer. We run the compiler on a copy of your code before quoting, so the estimate is based on the real error count. For older Node or React code that also needs structural work, see hiring for custom software.
End-to-end typed APIs: tRPC, Zod and OpenAPI
End-to-end typing means the front end knows exactly what each API accepts and returns, and a change on one side breaks the build on the other. Three tools cover most projects.
Zod describes the shape of data once and gives you both a runtime check and a TypeScript type from that description. Its documentation calls it a TypeScript-first validation library, now at version 4, and lists integrations with tRPC and React Hook Form. We use it at every boundary: form submissions, API input, webhook payloads, environment variables and LLM outputs.
tRPC describes itself as a way to build end-to-end typesafe APIs without schemas or code generation: the client imports the server's router type and gets autocomplete for every procedure's input and output. It is excellent when the front end and back end are both TypeScript and live in one repository, as in many Next.js apps.
OpenAPI is the better choice when other teams, mobile apps in other languages or partners will call your API. The server publishes a schema and clients generate typed code from it. A TypeScript developer you hire should be able to explain which of the three fits your project and why, rather than using one everywhere.
Front end, back end or both: where a TypeScript developer fits
Most TypeScript developers are strongest on one side, and the best hires for small teams are comfortable on both. Decide which you need before you post the role.
On the front end, TypeScript types React or Vue components, their props, and the data hooks that call your API. Frameworks such as Next.js, Nuxt and Astro are written with TypeScript in mind and use it for routing, configuration and content schemas. On the back end, Node with Express or NestJS, typed database layers and queue workers all benefit from the same checks.
Node itself has become friendlier to TypeScript. The Node.js documentation says versions from 22.18.0 run TypeScript files directly by stripping type annotations, as long as the code uses only erasable syntax, so enums, namespaces with runtime code and parameter properties still need a build step. It also notes that Node does not type-check the code; you still run the TypeScript compiler separately. That makes scripts and small services simpler to run, but it is not a replacement for a type check in CI.
TypeScript 6 and 7: does the new compiler change who you should hire?
Not much, but it rewards developers who keep projects current. According to the TypeScript team's blog, TypeScript 6.0 shipped on 23 March 2026 as the last release built on the original JavaScript codebase, and TypeScript 7.0 followed on 8 July 2026 as a native port written in Go, described as about ten times faster.
For a business, faster type checking means shorter CI runs and snappier editors on large codebases, which adds up over a year of development. The language you write stays TypeScript. Projects that rely on old compiler options or unusual build plugins may need some clean-up before they can move, which is one more reason to hire a TypeScript developer who keeps dependencies up to date rather than freezing them.
Ask candidates which version their last project used and how they handle upgrades. Someone who can describe a routine upgrade process is someone whose code will not trap you on an old toolchain.
How much does it cost to hire a TypeScript developer in India?
With us, projects are quoted per scope: a typed web app or portal starts at ₹60,000 (US$900), a typed marketing site at ₹10,000, an Android and iOS app in React Native at ₹40,000, and AI features at ₹40,000. Maintenance after the two free months starts at ₹8,000/mo a month.
Elsewhere, TypeScript developer rates vary a lot between hourly contractors, marketplace sellers on Upwork, Toptal or Freelancer.com, agencies and full-time hires. The spread reflects experience, whether code review and testing are included, and who carries the risk if the estimate is wrong. Hourly billing puts that risk on you; a project quote puts more of it on the developer.
When comparing quotes, line them up on the same scope and ask each candidate the same questions: is strict mode on, is input validated at runtime, is there a CI type check, who reviews the code, and what happens after launch? The cheapest quote often leaves out exactly those lines. For ongoing monthly work instead of a project, see dedicated web developer, and for the in-house question see in-house vs outsourcing.
Freelancer, agency or in-house: which way should you hire a TypeScript developer?
Choose by the shape of the work. A defined project with a clear end suits a freelance developer or small team; a product that needs daily changes for years may justify an in-house hire; a large programme with many specialists suits a bigger vendor.
Freelance team (like us)
Good for a new app, a conversion, a typed API or an audit. You talk directly to the developers, pay for scope rather than seats, and get code review between team members.
Marketplace contractor
Useful for small, well-specified tasks. Quality varies widely; platform fees apply; code review is usually absent unless you arrange it.
In-house hire
Best when TypeScript work is continuous and central to the business. Costs include salary, equipment, management time and the risk of a single point of failure.
Agency
Suits large, multi-discipline programmes with procurement requirements. Expect account managers between you and the developers.
Non-technical founders often mix models: a freelance team builds version one in TypeScript, then an in-house hire takes over using the handover docs. Our guide for non-technical founders covers that transition.
How long does a TypeScript project or conversion take?
A new typed web app takes 6–12 weeks with us; a typed marketing site 1–2 weeks. A conversion depends on the size of the codebase and the number of errors the compiler reports once strictness is raised.
For a new app, the first week settles the data model and the API contract, written as Zod schemas or tRPC routers before any screen is built. That contract is what lets front-end and back-end work proceed in parallel without surprises. Each following slice delivers one complete workflow: schema, API, UI, tests and a staging link you can try.
For a conversion, the first days go on measurement: we add TypeScript with allowJs, run the compiler and group the errors by area. You then get a plan in phases, each small enough to review, so feature work can continue in between. The conversion timeline table below shows the typical phases.
Who owns the TypeScript code and types after the project?
You own all of it: the repository, CI pipeline, cloud accounts, domains and any package registry entries are in your name, and we work as collaborators you can remove at any time.
Handover for a TypeScript project includes a README with local setup and the Node and TypeScript versions, a short note on the tsconfig choices and why they were made, the list of environment variables (names only), how types are shared between packages, and how to run the type check, linter and tests. That package is what lets you hire a TypeScript developer later, in-house or elsewhere, who can pick up the work quickly.
The two months after launch include free bug fixes and dependency updates. Anything beyond that, including confidentiality terms or support scope, goes into your written quote; the general rules are on our terms page.
Red flags when you hire a TypeScript developer
The biggest red flag is TypeScript used as decoration: .ts files full of any and casts, with strict switched off. It gives you the build step and none of the safety.
- strict is false in tsconfig and the candidate cannot explain why
- @ts-ignore or @ts-expect-error appears without a comment on what is being ignored
- API responses are cast straight to a type instead of being validated
- The same data shape is typed by hand in three places and has already drifted
- No type check in CI, so errors are only seen in someone's editor
- A proposal to rewrite your whole JavaScript app from scratch before shipping anything
- Hosting, repository or npm packages registered under the developer's account
None of these needs deep technical skill to spot. Ask for the tsconfig and one pull request, and search it for “any”, “as ” and “ts-ignore”.
Hire a TypeScript developer from anywhere in India
We work remotely with clients across India, by WhatsApp, Google Meet and your Git host, in English or Hindi. Payments go by UPI or bank transfer; overseas clients pay in USD through Wise, wire or PayPal.
Requests differ by city. Product companies in Bengaluru, Pune and Hyderabad often want extra TypeScript capacity for a module or a conversion. Fintech and D2C teams in Mumbai and Gurgaon ask for typed APIs with strict validation around payments. Logistics and trading firms in Kolkata and Visakhapatnam want internal portals that a small IT team can maintain. Growing software shops in Bhubaneswar, Mohali and Mysore bring us in for code audits and to set up strict standards on new projects.
Foreign companies hiring from India can read hiring developers in India for overlap hours and contracts.
Worked example: converting a logistics API to strict TypeScript
A hypothetical case shows how a conversion runs. Say a freight-booking business in Kolkata has a Node and Express API written in JavaScript over several years, used by a React dashboard and a driver app. Bugs keep appearing when fields change, and the one developer who knew the code has left.
A TypeScript developer would start by adding TypeScript alongside the JavaScript and running the compiler with checkJs to get an error count per folder. The shared models (booking, vehicle, driver, invoice) would be converted first and described as Zod schemas, so the API validates every request and the types come from the same source. Routes would then move to TypeScript one module at a time, each as a reviewed pull request, with a CI job failing any change that adds new type errors.
The React dashboard would import the shared types, so renaming a field on the API breaks the dashboard build immediately rather than in production. Strictness would rise in stages until the whole project runs with strict on. The business keeps shipping throughout; the work is quoted from ₹60,000 as custom software, with the final estimate based on the measured error count.
Checklist before you hire a TypeScript developer
Use this list when you compare candidates or proposals. A strong TypeScript developer will be happy to answer every point in writing.
- tsconfig from a recent project with strict on
- One real pull request you can read, with review comments
- Runtime validation at every external input: forms, APIs, webhooks, env vars
- A plan for sharing types between front end and back end
- CI that runs the type check, linter and tests on every push
- Incremental plan if converting JavaScript, with measurable phases
- Repository and all accounts in your name from day one
- Itemised quote, staged payments and a written support period
Ready to compare? Send us the same brief you send others and judge the replies side by side. Contact us on WhatsApp with your project or repository summary.