02 · Development framework

Dimension

02 · Development framework

Platform

Next.js + TypeScript + React

Next.js

Open-source (MIT) React framework for every Exo web app: routing, rendering, and APIs. Core standard · authority: EXO

TypeScript

Open-source (Apache-2.0) typed JavaScript, strict mode, for all application code. Core standard · authority: EXO

React

Open-source (MIT) UI library shared by web (Next.js) and mobile (Expo) apps. Core standard · authority: EXO

Status

Proposed (2026-10-02), pending team confirmation. Exo itself already runs on it; the repository contract still allows other frameworks until this is confirmed.

What it isCopy Anchor Link

The framework dimension answers: what is every app written in? One answer for every app: TypeScript, React, and Next.js for the web, and the same TypeScript and React on Expo for mobile (Deploy). There is no second path: no Svelte, Remix, Vue, or Angular.

One path means code, components, agents, and people move between apps without relearning a stack, and every Exo service (exo-verify, exo-analyze, Exo Key, the design system) is built and tested for exactly one target.

PlatformCopy Anchor Link

• Next.js (MIT, Vercel) for web apps: routing, server rendering, and API routes. Exo runs on Next.js 16.2 and React 19.2.
• TypeScript (Apache-2.0, Microsoft), strict mode, for all application code. JavaScript application sources are disabled (already required by the repository contract).
• React (MIT, Meta) for UI, shared by web (Next.js) and mobile (Expo / React Native).

All three are open source. Developers use them directly. Exo does not wrap or rename them.

Boundary and replaceabilityCopy Anchor Link

• The framework is a convention, not a hosted service, so there is no account, key, or bill.
• Next.js runs on any OCI host: Exo apps build to a standard container (Deploy) and do not depend on Vercel.
• Replacing the framework is a portfolio-wide migration, not a per-app choice. That is the point of an opinionated stack.
• Open change: the repository contract currently says "Application framework choice remains independent". It changes to Next.js + TypeScript + React once the team confirms this page.

Cost notesCopy Anchor Link

• License cost: $0 (MIT and Apache-2.0).
• The cost of one path is the alternatives given up: a team that prefers Svelte or Remix must build outside Exo.

StatusCopy Anchor Link

• Live: Exo, Construct, and the portfolio web apps already use Next.js, TypeScript, and React.
• Proposed: making it mandatory for every Exo app (pending team confirmation, 2026-10-02).