VCL
Write your code in Fastly's proprietary VCL language and we will compile and run it for you at the edge.
Learn to build on the Fastly platform
Fastly offers two types of edge service: highly performant and configurable services powered by Fastly VCL, and next generation Wasm-powered Compute@Edge services currently in private beta:
Compute@Edge
Compile your own Rust code into WebAssembly and Compute@Edge will run your binaries at the edge.
Whichever service type you choose, many concepts are common. And while not all Fastly features are supported by Compute@Edge yet, many more will be added in the coming months as we move towards general availability.
Domains and backends
Domains are hostnames that point to your services on Fastly. Backends are hostnames that point to the origin servers hosting your application. Healthchecks are pre-configured requests that Fastly data centers should make, to your backends, to confirm that they are ready to receive end user traffic.
Domains, backends, and healthchecks can be configured in multiple ways:
| Domains | Backends | Healthchecks | |
|---|---|---|---|
Using the fastly CLI | fastly domain create | fastly backend create | fastly healthcheck create |
| Using the API | Create domain endpoint | Create backend endpoint | Create healthcheck endpoint |
| Using VCL | Cannot be managed in VCL | backend { ... } declaration | Part of a backend { ... } declaration |
| Using the web interface | See Managing domains | See Managing origins | See Working with health checks |
HTTP and caching
Fastly respects the instructions you provide via HTTP headers such as Cache-Control. But you can also exert much finer-grained control over the way we load and cache your resources.
- Controlling cache freshness and TTL
- Deciphering cache hit and miss headers for shielded services
- Purging
- Shielding
- Clustering
- Staleness and revalidation
- Request collapsing
- Segmented Caching
- HTTP/2 server push
- Protected headers
Content delivery and transformation
As well as serving content loaded from your origin, Fastly can also manipulate that content in useful ways, or even generate content from scratch without loading anything from your origin.
Data storage
Fastly provides key-value stores at the edge that are highly optimized for reads.
Security
Learn how to configure Fastly to meet your security needs.
- Fastly IP ranges
- Web application firewall
- TLS options
- Detecting TLS connections
- Access Control Lists (ACLs)
Logging and debugging
Observability and debugging tools to help fix problems, test and monitor your Fastly services.