CloudflareEdgeServerless

Edge Computing with Cloudflare Workers

11 min readFebruary 1, 2026

Cloudflare Workers execute JavaScript at over 300 edge locations worldwide, placing your application logic within milliseconds of your users. Built on V8 isolates rather than containers, Workers start in under 5ms and consume a fraction of the memory. This guide explains the architecture, development model, and patterns for building production applications at the edge.

The V8 Isolate Model

Unlike traditional serverless platforms that spin up containers or microVMs, Cloudflare Workers use V8 isolates — lightweight execution contexts within a shared V8 engine process. Each isolate has its own memory heap and global scope but shares the underlying engine with thousands of other isolates. This architecture enables sub-millisecond cold starts and extremely high density, allowing Cloudflare to run your code at every edge location economically.

info

V8 isolates provide strong memory isolation via the same sandboxing technology used in Chrome tabs. One Worker cannot access another Worker's memory.

Understanding the Request Lifecycle

A Worker's entry point is the fetch event handler, which receives a Request object and must return a Response. The entire execution must complete within CPU time limits (typically 10-50ms on the free plan, up to 30 seconds on paid plans). Workers have no persistent filesystem — state must be stored externally in KV, R2, D1, Durable Objects, or external APIs.

src/worker.ts

export default {
  async fetch(request: Request, env: Env): Promise<Response> {
    const url = new URL(request.url)

    if (url.pathname.startsWith("/api/")) {
      return handleApiRequest(request, env)
    }

    // Serve static assets
    return env.ASSETS.fetch(request)
  },
}

Choosing the Right Storage Primitive

Cloudflare offers several storage primitives, each optimized for different access patterns. Workers KV provides eventually-consistent, read-optimized key-value storage ideal for configuration, feature flags, and cached content. R2 is S3-compatible object storage for large files and media. D1 is a SQLite-based relational database for structured data. Durable Objects provide strongly consistent, single-instance coordination for real-time collaboration, rate limiting, and stateful WebSocket handling.

Workers KV: High-read, low-write key-value pairs with global replication
R2: Object storage for files, images, and large blobs — no egress fees
D1: SQLite at the edge for relational queries and transactional workloads
Durable Objects: Strongly consistent stateful compute with WebSocket support

Optimizing Worker Performance

Keep your Worker bundle small — every kilobyte affects cold start time. Use ES module format and tree-shaking to eliminate dead code. Avoid importing large libraries when a few lines of custom code would suffice. For compute-heavy operations, consider using the Cache API to store results at the edge. Streaming responses with TransformStream can reduce time-to-first-byte for large payloads.

tip

Use wrangler tail to monitor real-time logs from your Worker in production. Combine with console.time() to identify performance bottlenecks.