Edge-First Architecture - Building for the Global Edge in 2026

// app/api/hello/route.ts
export const runtime = 'edge';

export async function GET(request: Request) {
  const country = request.headers.get('x-vercel-ip-country');
  return Response.json({
    message: `Hello from the edge in ${country}!`,
  });
}

export default {
  async fetch(request, env) {
    const cache = caches.default;
    let response = await cache.match(request);

    if (!response) {
      response = await fetch(request);
      response = new Response(response.body, response);
      response.headers.set('Cache-Control', 'max-age=3600');
      await cache.put(request, response.clone());
    }

    return response;
  },
};

Deno.serve(async (request) => {
  const url = new URL(request.url);
  const name = url.searchParams.get('name') ?? 'World';

  return new Response(`Hello, ${name}!`, {
    headers: { 'Content-Type': 'text/plain' },
  });
});

import { createClient } from '@libsql/client';

const db = createClient({
  url: process.env.TURSO_URL,
  authToken: process.env.TURSO_AUTH_TOKEN,
});

// Data replicates globally in milliseconds
const result = await db.execute('SELECT * FROM products WHERE id = ?', [id]);

export async function onRequest({ env }) {
  const { results } = await env.DB.prepare('SELECT * FROM users WHERE id = ?')
    .bind(userId)
    .all();

  return Response.json(results);
}

import { neon } from '@neondatabase/serverless';

const sql = neon(process.env.DATABASE_URL);

// Works in edge runtimes
const users = await sql`SELECT * FROM users LIMIT 10`;

export default {
  async fetch(request, env) {
    const response = await env.AI.run('@cf/meta/llama-2-7b-chat-int8', {
      messages: [{ role: 'user', content: 'Hello!' }],
    });

    return Response.json(response);
  },
};

import { streamText } from 'ai';
import { openai } from '@ai-sdk/openai';

export const runtime = 'edge';

export async function POST(req: Request) {
  const { messages } = await req.json();

  const result = await streamText({
    model: openai('gpt-4-turbo'),
    messages,
  });

  return result.toTextStreamResponse();
}

// Stale-while-revalidate pattern
export async function GET(request: Request) {
  const cache = await caches.open('my-cache');
  const cached = await cache.match(request);

  if (cached) {
    // Return cached, revalidate in background
    waitUntil(revalidate(request, cache));
    return cached;
  }

  const fresh = await fetchData();
  await cache.put(request, fresh.clone());
  return fresh;
}

export class Counter {
  state: DurableObjectState;

  constructor(state: DurableObjectState) {
    this.state = state;
  }

  async fetch(request: Request) {
    const count = (await this.state.storage.get('count')) || 0;
    await this.state.storage.put('count', count + 1);
    return new Response(`Count: ${count + 1}`);
  }
}

User Request
    ↓
Edge Function (300+ locations)
    ↓ Cache miss?
Regional Database (3-5 regions)
    ↓ Complex query?
Origin Server (1 region)

├── Edge CDN (Static Assets)
├── Edge Functions (API/SSR)
├── Edge Database (Turso/D1)
├── Edge KV (Session/Cache)
└── Edge AI (Inference)