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Fastly Edge SDK

Fastly’s network is designed to deliver fast, real-time experiences. Built on a highly customized version of Varnish, we use Varnish Configuration Language (VCL) and a global network of powerful servers to deliver intelligent caching and application logic at the edge.

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Modern network design

Unlike legacy CDNs, Fastly’s edge cloud was built to take advantage of modern networking capabilities. Our POPs are comprised of powerful servers with 100% solid-state drives and plenty of RAM, strategically located in major metropolitan areas to take advantage of higher density of Internet Exchange Points. We support the latest web protocols, including IPv6 and HTTP/2, for faster, more secure browser performance.

pop location

POP locations

Our POPs are strategically located at the center of the highest density Internet Exchange Points (IXPs), so we can serve content to your customers worldwide in milliseconds. We connect with multiple Internet Service Providers at each POP for additional bandwidth capacity and network redundancy, giving us the flexibility to always route traffic on the fastest available network.

modern web protocols

Modern web protocols

Fastly’s edge cloud supports modern web protocols, allowing you to take advantage of reduced browser overhead and improved efficiency. HTTP/2 is seamlessly integrated into our platform and available across our entire network. We support all the standard HTTP/2 protocol features as well as some optional features, including server push.

powerful servers

Powerful servers

Fastly POPs are comprised of powerful servers with plenty of RAM, solid-state drives (SSDs), and 10 plus 25 Gigabit per second Ethernet networking. Frequently accessed content is almost always served from RAM, while long-tail content is served from SSDs for a much lower Time to First Byte (TTFB), or time between receipt of an HTTP request and first response from cache. SSDs allow us to maintain larger caches without longer lookup times, resulting in a high cache hit ratio, and avoiding slow, costly traffic back to the origin.

Software-defined network

Software-defined network

Traditional, hardware-based routers and load balancers lack the necessary scalability and flexibility you need, so we designed our own custom routing and load balancing software. Our powerful servers enable us to run code at the network and application layers. Moving logic to these servers lets us provide faster, more flexible content delivery. Using patent-pending software, we consistently route end users to the most optimal Fastly POP and server while ensuring high availability.

Edge computing

Using Varnish Configuration Language (VCL), we enable you to perform intelligent caching and push application logic to the network edge, closer to your users. With our Edge Modules you can tailor how content is served at the edge based on a user’s location, language, or device type. Edge Dictionaries facilitate real-time edge decision making from every server on the Fastly network.

varnish vlc

Varnish & VCL

We use a highly customized version of Varnish to perform intelligent caching and push application logic to the edge. Our Custom Varnish Configuration Language (VCL) allows you to control most aspects of an HTTP request or response, including where content is fetched from, what’s cached, and how it’s cached and served.

Our powerful control panel and configuration API auto generate VCL for you. You can also write your own VCL, upload it alongside ours, and activate instantly. Fastly Support Plans and Professional Services Packages provide configuration assistance for more complex setups.

Edge Dictionaries

Edge Dictionaries

Fastly Edge Dictionaries — key-value pairs that your VCL can reference inside your Fastly service (like a database at the edge) — offer flexibility and control at the network edge, letting you make real-time decisions from every server in our network. Using an API call, you can add or update data inside an Edge Dictionary any time, without having to deploy a new version of your service.

Edge Dictionaries enable content sharing and social media outlets to update large referrer spam blacklists in real time. Image providers can quickly perform token checks for certain objects. Adtech companies can block bad actors at the edge, while global publishers can redirect users to a country site based on geolocation.

Edge modules

Edge modules

Our Edge Modules leverage VCL to perform custom logic at the edge, closer to your users. You can tailor how content is served for the best possible user experience.

  • Edge Authorization / Paywalls authorize requests faster by placing access at the edge rather than sending requests to your origin and back again.
  • Location Detection identifies where customer requests are coming from, so you can offer customized experiences based on location. For example, you can create a virtual boundary (geo-fencing) and send customers within that boundary localized content such as coupons or special offers.
  • Mobile Device Detection helps you determine what device a customer is using, so you can tailor content served; e.g. for iPhone users, you can serve a mobile optimized version of your pages.
  • Visitor Prioritization gives priority to active buyers if your site becomes overloaded during peak traffic events, directing casual shoppers to a waiting room.
  • Edge Side Include (ESI) is a Varnish feature which accelerates site performance by allowing you to mix both cacheable and uncacheable content. Fastly serves cacheable content and send requests for uncacheable content — such as the shopping cart — back to origin.

Real-time everything

Fastly’s edge cloud platform is designed to deliver powerful real-time experiences. We reduce risk by allowing you to make changes in seconds, rather than waiting for maintenance windows. Our logs and stats deliver timely web performance insights for rapid troubleshooting. These features empower you to deploy code multiple a day to support continuous integration / continuous delivery.

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Real-time logs

Our Varnish platform gives you access to real-time streaming logs, allowing you to monitor site performance and troubleshoot issues as they happen. You can also add conditions around logs, such as receiving alerts when broken links are detected. Fastly logs can be streamed to almost any major logging endpoint, including syslog servers, logging-as-a-service providers (like Sumo Logic, Papertrail, or Logentries), and Amazon S3 buckets. We also support encryption of log traffic using Transport Layer Security (TLS), so you can send sensitive information to log files without exposing data.

Real-time stats

Real-time stats

Using our analytics dashboard, you can access real-time and historical stats to monitor system health. You can see stats on percentage of requests per second, hit ratios, errors, miss latency, and global traffic profiles, including traffic spikes and instability. These insights can be particularly valuable during high-traffic events; if there’s an issue with your infrastructure, you can quickly identify and fix it while continuing to serve content to your users.

Real-time changes

Real-time changes

Fastly empowers you to operate at the edge, providing the speed and scalability to support continuous integration / continuous delivery (CI /CD). You can push new code or configuration changes to the edge and see them in production in seconds. If an error occurs, you can use version control for immediate rollback, instantly purging stale content and misconfigurations. Surrogate key purging simplifies the process even further by allowing you to purge all related content with a single invalidation request.