Fastly
Edge cloud computing and content delivery company
Fastly is an edge cloud platform company that provides a content delivery network (CDN), edge compute, and web application security services designed to run logic and cache content close to end users. It positions itself as a…
Definition
Fastly is an edge cloud platform company that provides a content delivery network (CDN), edge compute, and web application security services designed to run logic and cache content close to end users. It positions itself as a developer-focused alternative to traditional CDNs, emphasizing fast cache purging and the ability to run custom code at the edge via WebAssembly. Fastly's network is built from commodity hardware running its own software stack rather than relying on a single third-party edge provider, which lets it control caching behavior and compute execution down to low-level details that some competitors abstract away.
Overview
Fastly addresses a problem every high-traffic website eventually runs into: origin servers cannot serve every request directly to every visitor around the world without introducing latency and risking overload during traffic spikes. A content delivery network solves this by caching copies of content at points of presence closer to end users, but many established CDNs were built around the assumption that cached content changes infrequently, so invalidating a cache across a global network could take minutes. Fastly was designed around the opposite assumption, that publishers and retailers update content constantly and need changes to propagate everywhere in seconds, which shaped nearly every other part of the platform. Mechanically, Fastly's cache invalidation relies on a purging architecture that can push instructions to its entire edge network almost immediately, rather than waiting for time-to-live expiry or slow propagation across regional layers. Its Compute platform extends this edge presence to arbitrary logic: developers write code that compiles to WebAssembly, and Fastly's edge nodes execute that code inside a sandboxed Wasm runtime for each incoming request, avoiding the startup latency associated with spinning up a full container or virtual machine per request. Within the CDN and edge-compute landscape, Fastly sits closer to Cloudflare than to Akamai in ambition, since both companies now sell programmable edge execution rather than pure caching, but the two differ in execution model: Fastly bets on Wasm sandboxing while Cloudflare Workers historically used V8 isolates. Compared to a hyperscaler's CDN offering bundled into a broader cloud platform, Fastly presents itself as a narrower, developer-oriented specialist rather than a default add-on to an existing cloud account. In practice, Fastly is adopted by organizations whose content changes too often or too unpredictably for slow cache propagation to be tolerable, such as news publishers pushing breaking updates, streaming platforms delivering live and on-demand video, and e-commerce sites that need pricing or inventory changes reflected immediately. Its VCL-based configuration language gives experienced engineers precise, low-level control over caching and request-handling logic, and its bundled web application firewall and DDoS protection let some customers consolidate performance and security under one vendor. The tradeoff is that Fastly's configurability assumes a team with the engineering capacity to use it; VCL and Compute both have a steeper learning curve than a simple dashboard-driven CDN, and the platform is not positioned as the lowest-cost or broadest-footprint option in the market. Organizations without dedicated infrastructure engineers, or whose content update needs are modest, may find a more turnkey, fully managed CDN a better match, reserving Fastly for cases where real-time cache control or edge programmability is a genuine requirement rather than a nice-to-have.
Key Features
- Near-instant cache purging across the global edge network
- WebAssembly-based Compute platform for running code at the edge
- Real-time logging and analytics for edge traffic
- Integrated web application firewall and DDoS protection
- Image optimization service for on-the-fly resizing and format conversion
- VCL-based configuration language for fine-grained caching logic
- TLS termination and certificate management at the edge
- API and streaming media delivery optimized for high-bitrate content