Strict-mode type audit
A compile of your repository with every error grouped by folder, plus a migration order and risk list.
The Problem
Your JavaScript Codebase Has Outgrown Guesswork
It shows up when the code is too big for anyone to hold in their head. Refactors break distant files, API changes surprise the front end, and reviews turn into guessing.
01 · Refactors
Renaming one API field breaks screens nobody touched.
Shared types make the compiler list every screen a rename affects.
02 · Onboarding
New developers guess what shape each object has.
Typed models and editor hints show every field and where it's used.
03 · Bad data
Webhook data crashes code that trusted its shape.
Zod schemas check data where it enters, before any code relies on it.
04 · Reviews
Reviews miss the undefined values that crash production.
A type check in CI blocks any pull request that adds type errors.
Your app started as a few JavaScript files and now has hundreds. Renaming one field in the API breaks a checkout screen nobody touched, and you hear about it from a support ticket. New developers spend their first weeks asking what shape an order object has. Reviews catch style issues but miss the undefined value that crashes production on a Friday. Every new feature lands in code that's harder to change than the last one.
We start with a strict compile of your repository to see where types break, folder by folder. Then we move files to TypeScript in dependency order, with a CI check that stops new type errors from the first week. Zod validates data where it enters, and one shared type source keeps your API and UI in step. Bugs get caught in the editor, not by your customers.
One file at a time
Files move to TypeScript in dependency order while your team keeps shipping features.
Checks where data enters
Zod schemas validate API requests, forms, and webhooks, because types disappear at runtime.
Shared API and UI types
One type source feeds your Node.js API and your front end, so the two can't drift.
Our TypeScript Development Services Process
From Type Audit to Handover in Five Clear Steps
You see the error count and a fixed price before anything changes, then watch the migration arrive as small reviewed pull requests.
We run the compiler in strict mode on a copy of your repository and count the errors by folder. You get a migration order, the risky modules, and the plan that fits your codebase.
What's Included
What You Get From a TypeScript Development Company
Everything it takes to reach strict TypeScript and stay there: an audit, the migration, validation, shared types, a CI gate, and conventions.
Compare Options
DeveloperLook vs Freelancer vs Codemod Only
A freelancer suits a small typing job, and a codemod tool converts files in hours. Here's where each fits when you want strict TypeScript your team keeps.
| Feature | DeveloperLookBest fit | Freelancer | Codemod only |
|---|---|---|---|
| Migration plan | File order mapped first | Ad hoc, file by file | All files at once |
| Strict mode | Flags enabled one at a time | Often left off | Off, with any added |
| Runtime validation | Zod at every API edge | Depends on the person | Not included |
| API and UI types | One shared source | Often duplicated | Not included |
| Speed on big codebases | Weeks, in phases | Slow for one person | Hours for a first pass |
| Code review | Second engineer on every PR | Your team reviews | Your team cleans up |
| Cost | Fixed price per scope | Lowest hourly rate | Free open-source tool |
| Support after delivery | 30 to 90 days included | Varies by contract | Community issues only |
DeveloperLook
Freelancer
- Migration plan
- DeveloperLook: File order mapped firstFreelancer: Ad hoc, file by file
- Strict mode
- DeveloperLook: Flags enabled one at a timeFreelancer: Often left off
- Runtime validation
- DeveloperLook: Zod at every API edgeFreelancer: Depends on the person
- API and UI types
- DeveloperLook: One shared sourceFreelancer: Often duplicated
- Speed on big codebases
- DeveloperLook: Weeks, in phasesFreelancer: Slow for one person
- Code review
- DeveloperLook: Second engineer on every PRFreelancer: Your team reviews
- Cost
- DeveloperLook: Fixed price per scopeFreelancer: Lowest hourly rate
- Support after delivery
- DeveloperLook: 30 to 90 days includedFreelancer: Varies by contract
Projects We've Built
Web Platforms With APIs We Have Built
Platforms where a web app, an API, and an admin dashboard share data, which is where shared types pay off. We don't present them as TypeScript migrations.
Herile HR and Project Management Platform Website
- Business
- Dashboard
- SaaS Platform
Edutech E-Learning Web Design & Development
- Education
- Dashboard
- E-commerce
LifePulse Medical Web Design & Development
- Medical
- Booking System
- Dashboard
Unicom Fashion Ecommerce App and Admin Dashboard
- Fashion
- Dashboard
- E-commerce
What Our Clients Say
What Clients Say After Launch
Feedback from teams we have built web apps, dashboards, and websites for.
We had a pretty specific idea of what we wanted our website to become, but I wasn’t sure how easily we could explain all of it to a development team. There were quite a few moving parts, and we were working toward a deadline, so I expected a few things to get lost along the way. That never really happened. They understood what we were trying to achieve, kept us updated throughout the process, and got everything ready within the agreed timeline. The final site feels much easier to navigate, works beautifully on mobile, and is noticeably smoother for our customers. It was a huge relief seeing the original idea actually turn into the website we had in mind.
The mobile experience is probably my favourite part of the new site. We had spent a lot of time making sure the desktop version looked right, and the team kept pushing us to think about how everything would actually feel on a phone too. They were right. The navigation is clean, the interactions feel natural, and everything we’ve tested so far works exactly as it should. They also went through the links, forms, integrations, and other details more than once before launch, which I really appreciated. And even after going live, we could still reach out when something came up. The whole process felt friendly, organised, and surprisingly straightforward.
What I appreciate most is that the website is actually easy for us to manage now. We can update content ourselves instead of sending a developer a message every time we need to change something small. They also paid attention to the technical SEO side, which mattered to us because we didn’t want a new website to create problems for the traffic we already had. I’ve probably asked more questions than I should have since launch, but every question has been handled patiently and without any fuss. The team is easy to work with, they explain things clearly, and when we need something changed, they focus on getting it done rather than making the process complicated.
1,250+
Projects shipped
10+
Years of experience
Top 3%
Upwork Top Rated Plus
5 stars
Average review score
Want results like these?
Tell us what you are building. You get a reply within 24 hours on business days, then a written estimate.
Work Culture
Habits That Keep a TypeScript Codebase Strict
Types only help when your whole team trusts them. These habits keep the codebase strict after handover.
No any as an escape
We fix the type instead of silencing it with any or a ts-ignore comment. Every escape hatch we leave is listed, so you know where the gaps are.
Features ship during migration
We migrate in small pull requests on your main branch. Your roadmap keeps moving, and no migration branch sits unmerged for weeks.
Validate, don't assume
We treat data from APIs, forms, and webhooks as unknown until a schema checks it. That's where most production type bugs actually start.
Honest about plain JavaScript
If your project is small and stable, we'll tell you before we quote that JSDoc types may be enough. Not every codebase needs a full migration.
A second engineer reviews
Every pull request gets a second engineer's review before it reaches your team. Types catch shape errors, and reviews catch the logic ones.
Your repository, your rules
We work in your repository and accounts, which you can revoke at any time. The code, its history, and the typing guide stay with you.
Overview
When should you hire TypeScript developers for a JavaScript codebase?
DeveloperLook is where teams hire TypeScript developers to move JavaScript codebases to strict TypeScript and build typed web and Node.js apps. We audit the code, migrate it file by file, add Zod validation, and set one type source for API and UI. Projects start at $1,050, take 2 to 14 weeks, and you own the code.
DEVELOPERLOOK
Project facts · TypeScript Development Services
- Service
- TypeScript development services (strict migration, Zod validation, shared types, typed builds)
- Typical timeline
- 2 weeks for a starter sprint, 4 to 14 weeks for migrations and builds
- Platforms
- React, Next.js, Vue, Angular, and Node.js codebases
- Built with
- TypeScript, Zod, tRPC or OpenAPI codegen, ESLint, Vitest
- Experience
- 10+ years of development experience and 1,250+ shipped projects
- Post-launch support
- 30 to 90 days of post-launch support, depending on plan
- Communication
- Calls in US, UK, and AU business hours
- Starting price
- From $1,050 USD, fixed scope after a free type audit
Reviewed 10 Oct 2026 by Saimul Islam
Good fit
Teams with a large JavaScript codebase
Your React or Vue app has grown to hundreds of JavaScript files, and every refactor breaks something nobody notices until a customer does.
Startups short on typed talent
You want to hire TypeScript developers for a new product, but a full-time search would take months your runway doesn't have.
Full-stack teams with drifting API types
Your Angular front end and Node.js API describe the same order in two different ways, and the mismatch keeps showing up as production bugs.
CTOs planning a typed rebuild
You're weighing TypeScript development outsourcing for a rebuild and want a fixed scope, reviewed code, and a codebase your own team can maintain.
Agencies with typed client work
You've sold TypeScript web development services to a client and need engineers who deliver the Next.js project under your agency's name.
Not a fit
Building a new Node.js API
You need a new I/O-heavy API with queues and load tests, and typing is a side detail. Our Node.js Development Services page covers that build.
One small script
Your project is one small script or widget that only you maintain. Plain JavaScript is fine there, and JavaScript Development Services can help if needed.
Budget under $1,050
You need a few type errors fixed in a single file. Hiring a freelancer by the hour will cost less than our smallest plan.
Rewrite planned soon
You plan to rewrite the back end in Go or Python next quarter. Typing code you'll soon replace is money spent twice, so start with the rewrite.
Not sure we're the right fit?
Book a free call or message us. We'll tell you honestly whether we're the right team.
Pricing
Transparent Starting Prices for TypeScript Development Services
These are starting points in USD. Your final price depends on file count, type strictness, and test coverage, and you get a fixed proposal after a free type audit.
For teams that want TypeScript in place and new code typed, without touching everything yet.
$1,050one-time, USD
- Strict tsconfig with JavaScript and TypeScript side by side
- Up to 25 JavaScript files converted
- Type check gating every pull request in CI
- Typed API client from your OpenAPI spec or Zod schemas
- Written typing conventions for your team
- 30 days of post-launch support
Recommended
For JavaScript codebases of up to 150 files that need to move to strict TypeScript without a freeze.
$3,300one-time, USD
- Everything in TypeScript Starter Sprint
- Up to 150 files moved to strict TypeScript
- Zod validation on API inputs, forms, and webhooks
- Shared types package for API and front end
- Type errors fixed, not hidden with any
- 60 days of post-launch support
For teams that need a new web app and Node.js API built in TypeScript from the first file.
$7,200one-time, USD
- Everything in Codebase Migration
- New web app with up to 15 screens
- Node.js API with typed routes and Prisma or Drizzle queries
- End-to-end types through tRPC or OpenAPI codegen
- Vitest and Playwright tests on core flows
- 90 days of post-launch support
For Agencies
White-Label TypeScript Development for Agencies and Studios
You own the client relationship. We supply the engineering behind it as a TypeScript web development company: migrations, typed APIs, and new builds, delivered in your client's repository under your name. Your team stays the contact.
How the partnership works
White label: your client only ever sees your brand
- Your client
- You, the agency
- DeveloperLook
Share the repository
Send repository access, the backlog, and your client's review and branch rules.
- Client needs
- You share the details
- Details received
We audit and quote
We run a strict compile and return a phased plan with fixed prices.
- Scope and plan
- Proposal to resell
- Your quoteYOUR LOGO
Migrate and hand off
We ship reviewed pull requests, demo with you, and hand over the typing guide.
- Done by our team
- Your brand on it
- Handed to your clientDone
Partner with DeveloperLookDelivered under your brand
Stay client-facing
Your client sees your team in every demo, and our name stays off the work.
Fixed price per phase
Each migration phase has its own fixed price your agency can resell.
Strict TypeScript skills
Engineers who fix types properly instead of silencing them with any.
Flexible capacity
Add us for one migration phase or a steady run of client work.
The Right Technology for Your Project
Technology Stack
The type tools, front ends, back ends, and checks we use to move code to TypeScript and keep it strict.
- TypeScript
- Zod
- tRPC
- OpenAPI
GraphQL
React
Next.js
Vue.js- Angular
Node.js
NestJS
Express- Prisma
- Drizzle
- Vitest
- Playwright
- ESLint
- GitHub Actions
FAQ
Frequently Asked Questions
Straight answers on cost, migration time, hiring TypeScript developers, and where TypeScript fits.
Saimul IslamFounder & CEO, DeveloperLookStill have questions?
Send a message or book a call with the team.
TypeScript work with DeveloperLook starts at $1,050 for a starter sprint: strict config, a CI type check, and up to 25 files converted. Migrating up to 150 files costs $3,300, and a typed full-stack build starts at $7,200. Each price is fixed after a free type audit of your repository.
Most migrations of up to 150 files take 4 to 8 weeks. Time depends less on file count than on how dynamic the code is: mixins, untyped libraries, and objects built at runtime slow things down. Features keep shipping throughout, because we migrate in small pull requests on your main branch.
Hire TypeScript developers by testing how they handle messy data, not by counting years of experience. Ask how they'd type an API response they don't control, when they'd use unknown instead of any, and how they'd validate a webhook. TypeScript developers for hire who answer with Zod or type guards usually know the job.
TypeScript can be used anywhere JavaScript runs: websites, web apps, Node.js APIs, command-line tools, and desktop apps built with Electron. It compiles to plain JavaScript, so browsers and servers run the output as usual. Most of our TypeScript work is React, Vue, or Angular front ends and the Node.js services behind them.
Yes. A website built with Next.js, Astro, Nuxt, or SvelteKit can be written in TypeScript from the first file, and the build turns it into JavaScript the browser runs. For a small brochure site, the gain is modest. It pays off once the site pulls data from a CMS or an API whose shape can change.
Yes, TypeScript is widely used on the back end through Node.js, with frameworks such as NestJS and Express. Recent Node.js releases can even run TypeScript files directly by stripping the types, though they don't check them. New API builds have their own Node.js page, while this service types and migrates the back end you already have.
Yes, more than ever. GitHub's Octoverse 2025 report ranked TypeScript first on GitHub by monthly contributors in August 2025, ahead of Python and JavaScript. Microsoft has also ported the compiler to Go to make type checks much faster on large codebases. For your team, the practical reason is simpler: types catch shape errors before users do.
Microsoft, Google, Slack, and Airbnb all run large codebases in TypeScript. Microsoft created the language, VS Code's source is almost all TypeScript, and Google's Angular framework is built with it. Slack and Airbnb both published engineering posts about their migrations, and Airbnb released its ts-migrate tool along the way.
No. A big-bang conversion freezes features and usually ends with any types everywhere just to make the build pass. We let JavaScript and TypeScript files live side by side, migrate in dependency order, and enable strict flags one at a time. Codemod tools help with a first pass, but people still fix the types.
You do. All work happens in your repository and accounts, which you can revoke at any time. At handover, you get the typing guide, a list of remaining escape hatches, and CI checks your team keeps running. Bugs and small changes are covered for 30 to 90 days after delivery, depending on your plan.
Saimul IslamFounder & CEO, DeveloperLookStill have questions?
Send a message or book a call with the team.
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