Built to scale
Websites and web apps designed for growth: headless architecture, fast page loads, high-traffic readiness, horizontal scaling, multi-region deploys. Built to outlast your roadmap.
Diffco Services
Custom web development for modern businesses
Modern websites and web apps built by senior developers: fast, responsive, and easy to manage. Add AI agents, copilots, or data integrations when you need them, or simply ship a great website.
Sanity
Contentful
WordPress
Optimizely
Adobe
Shopify
Products we developed are used by
Awards and client reviews
- Top AI Development Company
- Top 10 Software Developers
- Top AI Developers
in California
- Top Software Development Company
Diffco 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 MultiverseTheir 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 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.
Development Solutions
Senior engineering depth
18+ years of web development across SaaS, e-commerce, enterprise, and AI-native products. The engineer who designs your architecture is the engineer who ships it.
AI infrastructure, when you need it
RAG pipelines, vector stores, agent runtimes, streaming responses, evals, and observability. Production-grade AI infrastructure is available when your product calls for it.
Compliance- and cost-aware
WCAG-, HIPAA-, and GDPR-aware, SOC 2-aligned design patterns. Cost-aware AI infrastructure (token, latency, model selection) is built in from day one when you’re shipping AI.
Choose your scope
Modern, responsive UIs
High-performance front-ends for web apps, dashboards, and admin products. Modular design systems, accessibility, performance budgets, engineered to last.
Front-end + Back-end
Front-end engineering backed by the back-end your product needs, wired into your APIs, databases, and (when needed) AI agents, RAG pipelines, or copilots.
Admin panels & internal tools
We design and build the front-end for admin panels and internal tooling, including AI eval dashboards, prompt management, and human-in-the-loop review interfaces when your product calls for them.
Integrations
We integrate third-party SDKs and services into your web front-end: payments, analytics, CRMs, and (optionally) AI model providers like OpenAI, Anthropic, or Google, for richer functionality at scale.
Diffco AI Methodology
A delivery method built for the AI era, not retrofitted to it.
Code is the cheap part now. Knowing what to build first, which foundation will hold at ten times the users, and what not to build at all is where projects are won.
Senior engineers make those calls. More than 100 AI agents per engineer do the building, around the clock, on our own delivery platform built on Claude Code and OpenAI Codex. A living plan with automatic checks keeps every agent inside the lines.
- You click through your product before we build it
- We bring you the parts of the job you never put into words
- Every architecture decision is written down with the alternatives
- Everything traces back to a goal, which is what makes change fast
- People make the decisions, and AI agents build inside them
- Before release, a person watches it work
- The whole project
is a document you can read
- Read the full methodology
What we bring
Tech stack
Web
- Contentful
- Sanity
WordPress- Optimizely
- Adobe
Magnolia- Shopify
Magento
Webflow
Frontend
JavaScript
React
Next.js
Angular
Vue.js
TypeScript
Tailwind
Material UI
Bootstrap
Backend
Node.js
Nest.js
Express
PHP
Python
ASP.NET
Java
Django
Flask
Ruby on Rails
Sinatra
C#
Symfony
Laravel
Yii
Go
Erlang
C/C++
Scala
Rust
Julia
R
AI models
Anthropic
OpenAI
Gemini
Hugging Face
Mistral
Qwen
Grok
Kimi AI
TypeSafe AI
Open weight models
Pinecone
Weaviate
pgvector
How we build
Seven stages, with a person signing off at every gate.
Every project runs through Production-Ready AI Engineering: seven stages, senior engineers directing 100+ AI agents, a check on every save, and a person signing off at every gate.
- 01
Discover
Human + AIWorkshops and stakeholder interviews with AI in the room. It cross-verifies inputs across calls, docs, and Slack threads, flagging blind spots, edge cases, and contradictions humans miss.
- 02
Plan
AIAI decomposes the work, picks architecture, models, and tools. Surfaces risks, costs, trade-offs, and conflicts between stated requirements, before they become bugs.
- 03
Align
HumanYou review and approve. Every decision is logged: an auditable trail before any code is written. No black box, no scope drift.
- 04
Build
Human + AIAI agents execute the approved plan inside engineered guardrails. Senior engineers steer and unblock. Sprint cadence with working artifacts, not status decks.
- 05
Validate
Human + AIThree independent layers on every release candidate: automated evals, senior code review, and dedicated Human QA, with manual and exploratory testing alongside security, performance, and accessibility checks.
- 06
Release
Human + AIProduction deployment, UAT, knowledge transfer, runbooks. Cutover is documented, reversible, and on a schedule you approve. Your team takes the keys, or we operate it for you.
- 07
Evolve
Human + AILaunch is a milestone, not a finish line. Monitoring, feedback loops, and incremental improvements keep the system compounding, and feed the next discovery cycle.
Every later change re-enters the same loop, and nothing skips a step.
Read the full methodologyEngagement models
Ways to work with us
Dedicated Team
Human-led, AI-assisted · Monthly commitment
A senior squad reserved for you on a monthly basis, using AI to move faster. Best for evolving products and complex domains. You get:
A senior team that’s always yours, never reassigned mid-project- Scope and priorities you can flex sprint by sprint
- Predictable monthly spend with no padding for risks you may never use
- Velocity from a team that already knows your codebase
Agent-Led Delivery
AI-built, senior-directed · Monthly commitment
Most of your monthly budget goes into AI agents, with a lean senior team directing and reviewing their work. You get:
- Maximum of your budget working on the build, not on headcount
- Working software at the end of every short sprint
- A preview of what each change touches before it’s built
- Sign-off on every release against standards agreed before coding starts
Why teams choose Diffco
Senior, dedicated teams
Senior experts on every project: AI/ML and software engineers, product and UX designers, and project and product managers. Assigned to you, never reassigned mid-project.
Streamlined development process
Agile delivery on Production-Ready AI Engineering, from early PoC to production rollout. Clear gates, your sign-off at each one, so you always know what’s happening and why.
Transparent billing
You always know:
- What you’re paying for
- How time is spent
- How costs connect to delivered outcomes
Audit-ready from day one
Every agent action is logged and every decision is traceable. SOC 2-aligned practices, HIPAA- and GDPR-aware delivery, and full IP assignment.
Clear communication and detailed reporting
From the first workshop to post-launch optimization, you get:
- Direct access to the Diffco team
- Regular progress updates and demo builds
- Clear documentation of decisions, architecture, and metrics
Own it, or let us run it
Knowledge transfer, runbooks, and documented, reversible cutovers if your team takes the keys. Ongoing support, monitoring, and improvements if you’d rather we operate it.
Our clients’ success stories
Our case studies
Enterprise website with product mini sites for mission-critical database software
The new website turned out very intuitive and easy to navigate, and we now have a competent team available to make changes on short notice.
Co-retail platform for D2C brands with CRM and ERP integration
Fine-tuned AI writing tutor for university students
Mobile-first booking website and custom ERP for an escape-room chain
General aviation marketplace that connects students, instructors, and aircraft
Best-in-class flight school website with a booking platform and online payments
Core platform support and development for a keyless-access startup
E-commerce for an architectural LED lighting company with real-time custom-fixture pricing
E-Commerce platform with custom loyalty platform and anti-counterfeit verification for a design-led pipe brand
Corporate online-banking platform launched in four months
Full solution architecture for a mobile-gamer loyalty platform on blockchain across mobile and web apps
AI Interactive mobile video ads for the voice-ad platform used by IKEA, Infiniti and HP
We were impressed by Diffco’s approach to the development process and how they engineer new solutions.
NFC table check-in and bill payment by WhatsApp or SMS for restaurants
AI-powered ID verification for car rentals provider
Police mobile field investigation app with sub-second offline ID scanning
Native mobile social app for nights out with a curated venue catalog and venue rewards
Mobile apps for 15-minute grocery delivery
We've developed an AI-powered app to create stunning in-home newborn photography
Custom face tracking and morphing for an iOS movie-parody app, 0.04s detection
Native mobile restaurant-matching app with taste-based AI and 1,000+ curated venues
Wi-Fi TV audio streaming stack for IoT devices, from firmware to mobile apps, CES 2018 honoree
Drug image recognition app built on a custom model for police and emergency crews
A marketplace for in-home veterinary house calls in the U.S. market
In-car child-monitoring mobile app with a custom ultra-low-latency video protocol
Explore our
amazing case studies
Frequently Asked Questions
Custom web app development is engineering bespoke web products, from corporate sites and e-commerce platforms to dashboards and AI-native applications. At Diffco every web project starts with discovery, then we ship under Production-Ready AI Engineering: senior engineers and (when relevant) AI agents in the same delivery loop. The result: web products that look modern and actually work.
We run on a Dedicated Team or Agent-Led Delivery: one predictable monthly fee for a team that’s always yours. Scope and priorities flex sprint by sprint. No padding for risks you won’t hit. See our blog for the full breakdown.
Discovery: 1–2 weeks. PoC: 2–4 weeks. MVP: 6–12 weeks. Full product: 2–3+ months for typical web; 3–4+ months for AI-heavy builds. Production-Ready AI Engineering lets us ship in weeks what most teams scope in months, without giving up production-grade quality.
Yes. Most of our web engagements are classic corporate, e-commerce, and SaaS sites. AI is available when your roadmap calls for it; not required.
It depends on team and budget. Sanity or Contentful for modern headless setups. WordPress for content-heavy sites with broad in-house editor needs. Shopify or Magento for e-commerce. Optimizely or Adobe for enterprise. We pick during discovery.
Yes. Technical SEO (schema, sitemaps, performance, Core Web Vitals) and analytics setup (GA4, Mixpanel, Segment, Plausible) are standard on every launch.
Yes. We’ve migrated sites from WordPress to Webflow, from Magento to Shopify, from custom platforms to Contentful, without losing SEO, content history, or traffic.
Yes. After launch we offer ongoing content, SEO, and feature support under a Dedicated Team or Agent-Led Delivery engagement. Most clients keep a small ongoing engagement post-launch.
Yes. We have senior product designers in-house. We can lead design and engineering as one team, or plug into your existing design org.
Yes. We’ve inherited and modernized everything from jQuery apps to legacy Angular and React codebases.
Both are non-negotiable. We design for WCAG 2.1 AA and run automated and manual a11y audits.
Yes. We take fast prototypes shipped on Cursor, Bolt, or Claude Code and turn them into products that run in production.
It depends on your product. REST for most public APIs. GraphQL when the front-end shape changes often. gRPC for high-throughput internal services. We pick during architecture.
Yes: relational (PostgreSQL, MySQL, SQL Server), NoSQL (MongoDB, DynamoDB), analytics (Snowflake, BigQuery, Redshift), and vector stores (Pinecone, Weaviate, pgvector) for AI workloads.
Let’s build something
great together.
Need other services?
AI & ML DevelopmentML, RAG, computer vision, and copilots, engineered to production standards with Production-Ready AI Engineering.
AI Agents DevelopmentCustom agents and multi-agent systems that do real work inside your CRM, EHR, ERP, and internal tools.
AI-Driven Product DiscoveryTwo weeks to answer “should we build this, and what would it cost to run,” before you spend six months finding out.
Team AugmentationSenior engineers who join your team, fit your workflow and culture, and start shipping from week one.
Mobile DevelopmentNative iOS and Android apps, with AI features built in, designed for real users from the first release.
