$15K–$80K typical projects
Direct answer
My TypeScript development engagements run $15K–$80K: the low end covers a focused build or a scoped JavaScript-to-TypeScript migration, the high end covers large codebase migrations or full product builds with typed contracts from database to UI. I bring 7+ years of production delivery, 20+ App Store launches on TypeScript React Native codebases, and Top Rated status on Upwork with $100K+ earned and verified client reviews. Every engagement starts with a codebase review or architecture session so the quote reflects your actual code, not a guess.
TypeScript pays for itself the day a refactor that would have been terrifying becomes mechanical — but only if the types model your domain instead of decorating it. The difference between a codebase with TypeScript and a typed codebase is design discipline, and that discipline is what you are actually buying.
You need an MVP or v2 shipped on budget with someone who makes architecture decisions and owns delivery end-to-end.
You need a senior IC to augment the team, rescue a codebase, or lead mobile + AI integration without months of hiring.
You need a reliable senior subcontractor for client projects — clear communication, store-ready quality, white-label friendly.
30 minutes — goals, stack, timeline, budget range.
Fixed milestones, clear deliverables, start date.
Weekly demos, async Slack updates, production standards.
Store launch, documentation, knowledge transfer.
A product team's JavaScript app has grown to the size where every change breaks something unrelated, and onboarding a new developer takes a month. I migrate it module by module — strict types on new code immediately, high-traffic modules converted first — while the team keeps shipping features. Within weeks, whole categories of production bugs stop occurring because the compiler catches them in CI.
A team loses days every sprint to mismatches between what the API returns and what the client expects. I establish a single source of truth — schema-derived types shared between backend and frontend, with runtime validation at the boundary — so a breaking API change fails the build instead of failing in production. Integration bugs drop to nearly zero and API changes become reviewable diffs.
A startup adopted TypeScript early but under deadline pressure, and now the codebase compiles while telling the truth about nothing — any everywhere, assertions papering over doubt. I tighten the compiler settings incrementally, replace the load-bearing any types with real domain models, and add lint gates so the debt cannot regrow. The team gets autocomplete and refactoring confidence back.
The compiler is the cheapest code reviewer you will ever employ, but only if the types carry real information. Good TypeScript makes illegal states unrepresentable: an order cannot be both shipped and unpaid, a user object cannot half-exist, an API response is either parsed and valid or rejected at the boundary. When the domain lives in the types, refactoring becomes mechanical — change the type, follow the compiler errors, done — and that is where teams feel the payoff, because refactoring fear is what slows mature codebases to a crawl.
Bad TypeScript, by contrast, is JavaScript wearing a costume: any at every awkward moment, assertions instead of validation, types written to silence the compiler rather than describe reality. It costs you the annotation effort and returns none of the safety. A codebase full of it is arguably worse than plain JavaScript, because it manufactures false confidence.
The rule that makes migrations survivable: the team never stops shipping. I start by enabling TypeScript alongside the existing JavaScript so both compile in one build, then set the ratchet — all new code is strict TypeScript from day one, so the debt stops growing before we touch a single old file. Existing modules convert in dependency order, highest-churn files first, because types deliver the most value where code changes most often.
Each converted module lands as an ordinary reviewed pull request, not a big-bang branch that rots for weeks while main moves on. Compiler strictness tightens in stages, and a simple metric — typed lines versus untyped, tracked weekly — keeps progress visible to non-technical stakeholders. A mid-sized product codebase takes six to twelve weeks this way, and at no point is there a freeze, a rewrite branch, or a scary merge day.
For migrations, the honest driver is not line count — it is how dynamic the JavaScript is. Code that passes objects of shifting shape through event buses and metaprogramming takes several times longer to type truthfully than boring, well-structured code of the same size. Test coverage matters too: migrating untested code means I am also writing the safety net as I go. Dependency quality is a third factor — libraries without type definitions each become a small side project.
For greenfield builds, cost tracks feature surface like any development work, with typing itself adding little — TypeScript slows an experienced engineer down single-digit percent and pays it back within the same project. The top of the range is large migrations combined with architectural repair, because most codebases that hurt enough to migrate have structural problems the migration surfaces, and fixing them together is cheaper than twice.
Everyone lists TypeScript; almost nobody is good at it. The fastest filter: ask a candidate when they last used any deliberately and why. Strong engineers have a considered answer about boundaries and pragmatism; weak ones either claim never — which means they use assertions instead, a worse habit — or cannot articulate a policy at all. Ask how they handle data crossing into the system from outside: the correct answer involves runtime validation at the boundary, because TypeScript types are erased at runtime and anyone who trusts them against external input has not been burned yet, or has not noticed.
Ask to see a type they designed that prevented a class of bugs, not just annotated a function. And for migration work specifically, ask about strategy: anyone proposing a code freeze or a long-lived rewrite branch has not done this at scale on a live product.
If the codebase is a prototype you expect to throw away or rewrite within six months, migrating it is money spent typing code that will not live long enough to repay it. If the team is one or two people who hold the whole system in their heads and ship confidently, the coordination benefits that justify types have not kicked in yet — adopt TypeScript for new code and leave the rest alone. If the product is dying from lack of users rather than lack of engineering quality, no migration fixes that; spend the budget on the product.
And sometimes the right scope is partial: type the API boundary and the domain core, leave the long tail of stable, rarely touched files in JavaScript indefinitely. Full conversion is a default, not a law, and part of what you pay a senior engineer for is knowing where to stop.
You approve milestones and a price before any build starts — no open-ended hourly surprises.
You see running software each week, not status reports, so you can course-correct early.
The person who scopes the work is the person who builds it — no junior layers, no agency markup.
Top Rated on Upwork with public client reviews and $100K+ earned, plus contributions to Expensify. Check the receipts before you commit.
Chat-Based Financial Collaboration
Contributed 50+ merged pull requests to New Expensify — the production React Native app used by millions for chat-based expense management — working through Expensify's fully public open-source process alongside their core engineers, and recognized with a Guest Engineer invitation to their Curaçao offsite.
Food Truck Discovery Platform
Production food-truck discovery platform for US cities — customer and vendor React Native apps on iOS and Android, plus customer and vendor web, with AI features. Helps people find trucks nearby while vendors manage schedules, orders, and events.
Rewards & Engagement Platform
End-to-end React Native app for the US market with gamified rewards, real-time engagement, and secure payment flows — built from product scoping to App Store launch.
A scoped migration of a mid-sized product codebase typically runs $15K–$40K over six to twelve weeks, done module by module while your team keeps shipping. Large codebases, or migrations combined with architectural cleanup, run $40K–$80K. Cost tracks how dynamic the JavaScript is and how much test coverage exists — not raw line count, which is a poor predictor.
Six to twelve weeks for a typical product codebase, converting in dependency order with new code strict from day one. You feel benefits in the first two weeks — new code stops adding untyped debt immediately — rather than at the end. Timelines stretch when code is heavily dynamic or untested, because truthful types and a safety net have to be built together.
Migrate, almost always. Incremental migration keeps your product shipping, preserves years of accumulated bug fixes, and delivers value from week one. Rewrites discard that knowledge, freeze your roadmap for months, and historically fail more often than they succeed. The exception is a small prototype whose architecture is genuinely dead — under roughly twenty thousand lines, a rewrite in strict TypeScript can be faster than untangling.
Projects typically fall in the $15K–$80K range depending on scope, integrations, and timeline. I provide a fixed-scope proposal after a 30-minute scoping call.
MVPs often ship in 8–12 weeks. Production systems with AI backends or RAG may run 12–20 weeks. Rescue and audit engagements can start within days.
Yes. I work with founders, CTOs, product teams, and agencies worldwide — US, UK, EU, and APAC time zones with async updates and weekly demos.
Yes. I specialize in React Native + Python (FastAPI) + AI (RAG, agents, OpenAI/Claude) under one senior owner — fewer handoffs, faster shipping.
Book a free 30-minute scoping call on this site, hire through Upwork, or email dhairyasenjaliya@gmail.com with your brief and timeline.
30-minute scoping call · Clear milestones · Senior engineer ownership