Experience. Clarity. Enthusiasm.

Frontend architecture that carries your product — delivered in person.

We have seen a lot and know the options: which paths carry — and which end in a dead end. The result is never an off-the-shelf solution, but the right combination of proven building blocks. Deliberately small: no juniors, no handover to third parties.

Book an intro call Our expertise

15 minutes, no strings attached — you talk directly to one of the two Sebastians. Prefer email? contact@sebastian-consulting.com

Trusted by teams at

Years of frontend and web experience

Projects delivered

Companies and brands served

Our approach

More speed requires
more judgment.

AI accelerates implementation. What matters is what gets built, how it fits the architecture and what quality looks like. That is where we take responsibility.

Clarify

We clarify goals, context, risks and quality criteria – unambiguously enough for people and AI to build the same product.

Lead the architecture

We make and document the decisions that keep systems sound, understandable and adaptable.

Verify

We review outcomes by risk and establish tests, reviews and guardrails that turn speed into reliable delivery.

Results that last.

Meet the two consultants

Regrello

B2B SaaS

Internationalization of an enterprise platform — static UI and millions of user-generated objects, translated with LLM support. Users across languages work seamlessly on the same data.

DWS Group

Fintech

Investment platform for European and Asian markets. A resilient frontend architecture became a product that runs in more than ten countries today.

Heidelberg Materials

Industry · Enablement

Established frontend architecture and enabled teams to deliver more consistently and faster — with standards the next team will understand, too.

Case study

How Regrello went multilingual.

For Regrello we internationalized an enterprise platform — static UI and millions of user-generated objects. The result: less performance risk, shorter development cycles and a developer experience that rolls out new languages in seconds.

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Scalable architecture

Modular structures for continuous growth.

Top performance

Fast delivery and stable user experiences.

Team Enablement

Sharing knowledge, establishing standards, increasing impact.

Our focus. Your advantage.

Strategy, technology and craft thought of as one — executed with precision.

Craft

React & Modern Web

React and TypeScript in enterprise settings — including the ecosystem decisions behind them.

Platforms & Products

Design systems, monorepos and platforms on which multiple teams deliver in parallel.

Performance & Quality

Core Web Vitals, bundle budgets and code standards — measured, not guessed.

Stewardship

Strategy & Architecture

Target picture, architecture decision and migration path — reasoned, documented, built to carry.

Enablement & Mentoring

Pairing, reviews and standards that stay when we leave.

Architecture Supervision

Specifications, reviews and guardrails for AI-assisted delivery – so speed does not multiply complexity.

Two architects. Nothing in between.

Nobody off the bench, no juniors, no handover to third parties. You work with exactly the two architects who own your frontend — real project responsibility, verifiable experience, delivered together.

Sebastian Werner

Frontend architecture & developer experience. React, TypeScript, internationalization and code quality.

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Sebastian Fastner

Fullstack & platform. TypeScript, React, Convex and infrastructure — from the surface to the backend.