State in five places
Server data copied into global stores, local state and URL parameters that drift apart. Bugs look random because one value has three owners.
React front ends that stay fast after the hundredth feature
Diffco builds React applications — SaaS products, dashboards, customer portals and the interfaces of AI features — and takes over the ones that have slowed down. Senior engineers set the architecture, state model and design-system rules; AI agents build inside them; a person checks every key screen in a real browser before it ships.
Products we developed are used by
Awards and client reviews
- Top AI Development Company
- Top 10 Software Developers
- Top AI Developers
in California
- Top Staff Augmentation Company
Their commitment to excellence ensures our platform remains robust and adaptable to our evolving needs. With their expertise, we've successfully enhanced our offerings, making our collaboration highly effective.
Pete GualfettiHead of Design and Integration at Good2GoWe were impressed by Diffco's approach to the development process and how they engineer new solutions. They look ahead, learn about your product and strategy, and develop sophisticated, highly functional solutions.
Stas TushinskiyCEO & Co-founder at InstreamaticDiffco supplied us with the skilled engineers we needed to meet our ambitious goals. Their account manager proactively addressed concerns, ensuring our expectations were met.
Razvan SpatariuSenior Software Engineering Manager at MultiverseDiffco took on a complex financial system build for us — the kind of work that touches fund accounting and compliance, where there’s no margin for error — and they delivered. They helped us shape our AI product strategy rather than just executing tickets. Real ownership of the outcome.
Adam HooksCEO at Vero K12Diffco handled discovery for two complex health tech AI products for us. They’re technically sharp, honest about what’s actually worth building, and easy to work with. They moved fast without cutting corners and understood the healthcare space. Highly recommend.
Mark MagazuPrincipal at M3 Veterinary Innovation AdvisorsDiffco's expertise and engineering approach increase the reliability and efficiency of our IoT infrastructure. Diffco has proven to be a reliable partner with exceptional expertise. I highly recommend their services.
David C ThompsonSenior Digital Initiatives director at ChemTreatThe quality and consistency of the team make Diffco stand out from other vendors.
Art DanielovCEO at FlashgridThey were communicative, consultative, and helpful. They went above and beyond all the way. What an amazing team. I will work with them again and again.
Don MarklandCEO at Accountability NowDiffco turned our concept into a polished product from scratch, delivering on a tight timeline. Clear communication, organized project management, and a strong mix of creativity and technical expertise produced an app that exceeded our vision.
Mason MeninCo-founder at WYA Group, Inc.
Where React apps slow down
React makes the first version easy.
The fiftieth screen is where it gets expensive.
The problems never show up in the demo. They show up a year in, when every change touches five components and nobody is sure which state is the real one.
Re-renders nobody measured
A keystroke re-renders the whole page; a table of 2,000 rows freezes a laptop. Performance was never budgeted, so it was never tested.
A design system in name only
Three button components, four spacing scales and a Figma file nobody trusts. Every new screen re-decides what the last one already settled.
Bundles that only grow
Every library anyone ever tried still ships to every user. Load time creeps up one release at a time until mobile users leave.
Accessibility as a retrofit
Keyboard traps, missing labels and low contrast found by a customer’s procurement team, after the contract was already on the line.
The upgrade nobody can scope
Class components, deprecated APIs and a router two majors behind. The move to React 19 stays on the backlog because no one knows what it breaks.
Server state lives in one data layer. UI state stays beside the component that owns it. Every key screen ships with a performance budget CI enforces — fast is something we test, not something we hope for.
React development services
From a first dashboard to a front end at scale
New React products
SaaS apps, customer portals and dashboards in React and TypeScript, with the architecture, state model and design system decided in discovery, not discovered in month six.
Best for:Founders and product teams starting a product meant to last.
Design systems and component libraries
Design tokens, accessible components and Storybook documentation matched to your Figma file and shared by every team, so a new screen is assembly, not invention.
Best for:Companies running several products or teams on one UI.
Performance and accessibility fixes
Profiling, React Compiler adoption, re-render and bundle fixes, and a WCAG 2.1 AA audit with the fixes — each measured before and after.
Best for:Products where speed or an enterprise deal is now at stake.
Upgrades and migrations
Class components to hooks, older React to React 19, Create React App to Vite, jQuery or AngularJS to React — screen by screen, with the product live throughout.
Best for:Teams stuck on an upgrade nobody can scope.
Interfaces for AI features
Chat and copilot surfaces, streaming responses, human-review queues and eval dashboards: the part of an AI feature users actually touch, built to show uncertainty honestly.
Best for:Products adding AI that users have to trust.
Choosing the framework
AngularVueReact
Best whenLarge teams want strict conventionsA small team wants simplicity
The widest ecosystem and hiring pool matter
The widest ecosystem and hiring pool matterStructureOpinionated, batteries includedOfficial router and storeA library; architecture is decided in discovery
A library; architecture is decided in discoveryServer rendering and SEOAngular SSRNuxtNext.js or React Router framework mode
Next.js or React Router framework modeMobile code sharingIonic web views or NativeScriptIonic web views or NativeScript-VueReact Native shares language, patterns and logic
React Native shares language, patterns and logicEcosystemEnterprise-focusedSmallerThe largest set of libraries and UI kits
The largest set of libraries and UI kitsTypical riskSteeper learning curveFewer enterprise component kitsToo many choices without an architecture
We build in all three, and we’ll recommend against React when your team or constraints favor another framework.
How we build
Senior engineers decide the architecture. AI agents build the screens. A person checks every one before release.
Our own AI delivery platform puts your plan, your design system and your front-end rules in front of every agent before it starts — which state library, which component to reuse, which performance budget applies — and automatically checks everything it produces on every change.
Senior engineers decide what to build and how; more than 100 AI agents per engineer build inside those rules around the clock. Before release, a person watches each key user task work in a real browser and signs off against a standard agreed before the code existed. Ask for the same fix twice, and it becomes a rule every agent follows from then on.
The loop, on a React product
- You say what the screen must do — and on which devices
- We show the components, data and routes it touches
- You approve a clickable version before it’s built for real
- Agents build inside the plan, with automatic checks on every change
- A person watches it work in a real browser and signs off
- 100+AI agents per engineer, directed by senior engineers
- Every changechecked against the plan and the design system
- WCAG 2.1 AAthe target for every screen, with automated checks on every change
What you get
A front end your next engineer can read on day one
One source of truth for state
Server data in one cache layer, UI state beside the component that owns it, so every bug has one place to live, not three.
A design system people use
Tokens and components matched to Figma, documented in Storybook and enforced by automatic checks, so new screens reuse instead of reinvent.
Speed and accessibility checked on every change
Performance budgets and accessibility checks run in CI. A screen that gets slower or loses a label doesn’t ship.
Code and decisions you own
TypeScript throughout, tests beside the code, and the plan, rules and decision log as plain files in your repo — yours to keep with any team.
Why teams choose Diffco for React
Engineers who have shipped React to real users, not just demos
We’ve shipped React inside a client’s own product
For Maze, we delivered the AI Moderator inside Maze’s own React and Next.js codebase, scope by scope, through its pull-request review, including the live interview interface rebuilt in WebGL.
We’ve taken over a React codebase mid-flight
As Gitcha’s embedded team, we refactored a legacy React and Node codebase, modernized its AWS infrastructure and shipped Version 2 on time.
We’ve shipped the marketplace front end
Vitality Access runs on Next.js 15 and React 19, with prices computed on the server and row-level security as the access boundary.
Design and engineering in one team
Senior product designers in-house, so the Figma file and the component library are the same decisions, made once.
We tell you when React is the wrong tool
A content site may belong on a CMS; an internal tool may not need a single-page app. We say so before you spend.
Senior team, in your time zone
The engineer who designs your component architecture is the engineer who ships it — in Pacific time, with an office you can visit.
Sales tools · SaaS
Next-gen sales tools for premium glass wall systems.
NanaWall makes moving glass wall systems for homes, offices and commercial spaces. Diffco develops its next-generation sales applications: an iPad app its teams use to configure, showcase and track projects, and the client web app where customers follow their own.
- iPad app · client web appBuilt for NanaWall: the sales team’s tool and the one its customers use.
- 40 yearsNanaWall’s years making premium glass wall systems.
- 20+ showroomsNanaWall showrooms across North America.
Two ways to start
Audit what you have, or hand us the build.
React front-end audit
One to two weeks. A senior front-end architect, with agents reading the whole codebase, profiles your slowest screens, maps state and data flow, audits accessibility and bundle size, and delivers ranked fixes with an estimate given as a range.
Fixed price, agreed up front- Every finding ranked, with its fix and its effort
- The report is yours — use it with any team, including your own
Build with Diffco
Discovery in a few days to two weeks; a clickable walkthrough within the first weeks; working screens soon after. Senior engineers decide, agents build inside the plan, a person signs off in a real browser. Monthly team allocation or a fixed scope after discovery.
- Estimate given as a range with its open questions
- The plan and the design system are yours from week one
- Handover with runbooks and a codebase you can read
What we bring
The React ecosystem — and the checks that keep it fast
React core
React
TypeScript
JavaScript
Vite
Next.js
React Router
State and data
TanStack Query
Redux Toolkit
Zustand
GraphQL
Apollo
tRPC
UI and design systems
Tailwind CSS
Material UI
shadcn/ui
Radix UI
Storybook
Figma
AI in the interface
OpenAI
Anthropic
Vercel AI SDK
Streaming UI
Eval dashboards
Quality and performance
Jest
Vitest
React Testing Library
Playwright
axe
Lighthouse CI
Sentry
Success stories of our clients
Led Core Platform Development & Supported Product Growth Through Seamless Operations
We built the AI Moderator that runs Maze’s user research interviews
We helped Gitcha launch Version 2 by refactoring legacy code, upgrading AWS infrastructure, and improving CI/CD pipelines
A marketplace and the admin it needed, at under half the first estimate
Full development + AI agentic product discovery for Happier, a top-rated meditation app
We built an internal mobile app and web portal that aggregate data from multiple providers to track team productivity
Led Core Platform Development & Supported Product Growth Through Seamless Operations
We built the AI Moderator that runs Maze’s user research interviews
Explore our
amazing case studies
Let’s build something
great together.
Frequently Asked Questions
Because the architecture is decided before anything is built. Senior engineers set the state model, design system and performance budgets; AI agents build inside that plan; a person checks each key screen in a real browser before release. Fast delivery, and a codebase your team can still change a year later.
It depends on where the app lives. React with Vite fits products behind a login: dashboards, portals, internal tools. Next.js fits products that need server rendering, Server Components or SEO. We decide in discovery and write the reason down.
Yes. We start with a short audit — state, data fetching, component structure, test coverage — then fix, refactor or rebuild screen by screen while the product stays live. We’ve inherited everything from class-component apps to prototypes generated in a weekend.
With budgets, not promises. Each key screen gets a load-time and bundle-size budget agreed up front, CI checks it on every pull request, and a screen that gets slower doesn’t ship. Fixes are measured before and after, on real traffic where possible.
It’s designed in, not audited in at the end. We build to WCAG 2.1 AA, run automated checks on every change, and do manual keyboard and screen-reader passes before release — so an enterprise buyer’s review finds evidence, not surprises.
Yes. We scope the upgrade first — deprecated APIs, libraries that block it, test coverage — then move in slices behind the running product. The React team deprecated Create React App in 2025; most apps move to Vite or Next.js, and adopt the React Compiler on the way.
Either. We have senior product designers in-house, or we work with your design team and turn its Figma file into a component library both sides trust.
A front-end audit takes one to two weeks. A focused product or a single product area is estimated in discovery, as a range with the open questions that make it wide; larger platforms ship in usable releases, with a clickable walkthrough in the first weeks.
Engagements start with a fixed-price audit or discovery, agreed up front. Builds run on a monthly team allocation or a fixed scope after discovery, with the estimate given as a range and the open questions that make it wide.
Yes. A monthly allocation of senior React engineers who work in your repo, sprints and review process, directed by your leads, with our platform and an architect behind them.
You do — the code, the component library, and the plan, rules and decision log, kept as plain files in your repo from the first commit and yours to take to any team.
Need other services?
Vibe Code RescueYour Lovable, Bolt, Replit or Cursor prototype worked. Our senior engineers stabilize, harden or rebuild it for production.
Claude Code DevelopmentOur AI delivery platform runs on Claude Code. We build with it, and we set your team up on it.
Fintech Software DevelopmentPayments, banking platforms, fund accounting and receipt AI, built where money correctness comes first.
Web DevelopmentModern websites and web apps engineered by senior teams directing AI agents.
Mobile DevelopmentNative iOS and Android apps, with AI features built in, designed for real users from the first release.
AI & ML DevelopmentML, RAG, computer vision, and copilots, engineered to production standards with Production-Ready AI Engineering.
Custom Software DevelopmentWeb apps, platforms, and internal tools, built in weeks instead of months, from PoC to production.
