One of the key features of Apache Traffic Server™ is its modularity. Features that aren’t needed in the core simply aren’t there. This helps to provide an additional guarantee that our core can remain fast by concentrating on the things that we always provide: caching and proxying.

All other functionality can be moved into plugins and by offering a consistent C API, everyone can implement their own functionality, without having to touch the core.

Stable plugins

Plugins that are considered stable are installed by default in Traffic Server releases.

Delegates the authorization decision of a request to an external HTTP service.
AWS S3 Authentication
Support for Amazon S3 authentication features.
Background Fetch
Proactively fetch content from Origin in a way that it will fill the object into cache.
Combo Handler
Provides an intelligent way to combine multiple URLs into a single URL, and have Apache Traffic Server combine the components into one response.
Configuration Remap
Override configuration directives on a per-rule basis.
Implements the Edge Side Includes (ESI) specification.
Generate arbitrary response data.
Compress or deflate cache responses.
Header Rewrite
Modify requests and responses based on incoming and outgoing headers and other transaction attributes.
Health Checks
Define service health check links.
Regex Remap
Configure remapping rules using regular expressions.
Regex Revalidate
Configurable rules for forcing cache object revalidations using regular expressions.
Stats over HTTP
Provide an HTTP interface to all Traffic Server statistics.
Log TCP metrics at various points of the HTTP processing pipeline.
Allows HTTP clients to debug the operation of the Traffic Server cache using the X-Debug header.

Experimental plugins

Plugins that are considered experimental are located in the plugins/experimental directory of the Traffic Server source tree. Experimental plugins can be compiled by passing the –enable-experimental-plugins option to configure:

$ autoconf -i
$ ./configure --enable-experimental-plugins
$ make
Balances requests across multiple origin servers.
Buffer Upload
Buffers POST data before connecting to the Origin server.
Cache Key Manipulation
Allows some common cache key manipulations based on various HTTP request elements.
Cache Promote
Provides additional control over when an object should be allowed into the cache.
Allows to Collapse multiple Concurrent requests by downloading once from the Origin and serving all clients in parallel.
Emits Traffic Server metrics in a format that is consumed by the Epic Network Monitoring System.
Escalate: when the origin returns specific status codes, retry the request at a secondary origin (failover/fail-action)
Deny or allow requests based on the source IP geo-location.
Header Frequency
Count the frequency of headers.
Adds support for HTTP Pipes.
Implements the memcache protocol for cache contents.
Implements the Metalink download description format in order to try not to download the same file twice.
Money Trace
Allows Trafficserver to participate in a distributed tracing system based upon the Comcast Money library.
MP4 streaming media.
MySQL Remap
Allows dynamic remaps from a MySQL database.
Remap Purge
This remap plugin allows the administrator to easily setup remotely controlled PURGE for the content of an entire remap rule.
Signed URLs
Adds support for verifying URL signatures for incoming requests to either deny or redirect access.
SSL Headers
Populate request headers with SSL session information.
Stale While Revalidate

Refresh content asynchronously while serving stale data.

TS Lua
Allows plugins to be written in Lua instead of C code.
WebP Transform
Converts jpeg and png images to webp format.