|Developer(s)||Apache Software Foundation|
6.1.1/ 8 February 2016 
|Type||Web cache, Proxy server|
|License||Apache License 2.0|
The Apache Traffic Server (ATS) is a modular, high-performance reverse proxy and forward proxy server, generally comparable to Nginx and Squid. It was created by Inktomi, and distributed as a commercial product called the Inktomi Traffic Server, before Inktomi was acquired by Yahoo!.
Shortly after Yahoo! released the TS source to Apache as an Apache Incubator project in July 2009, a guest editor on Yahoo!'s online publication OStatic  stated that Yahoo! uses TS in production to serve more than 30 billion objects per day on sites like the Yahoo! homepage, and Yahoo! Sports, Mail and Finance.
On April 21, 2010, the Apache board accepted Traffic Server as a TLP, graduating the project out of incubation.
As of February 2016[update], ATS is in version 6.1.1, with quarterly minor versions scheduled. Beginning with version 4.0, all releases are considered stable for production, and follow regular semantic versioning. No more developer preview releases will be made, instead, the Git master branch is considered preview quality at all times. Long term support is provided for the last minor version within a major release, for one added year.
ATS has, as of v6.0.0, good support for the next generation HTTP protocol, HTTP/2 (aka H2). On the Is TLS Fast Yet site, it scores 100%. ATS is actively developed and supported by several large companies, as well as many individual contributors.
Features and performance
The OStatic post describes TS as shipping "... with not only an HTTP web proxy and caching solution, but also ... a server framework, with which you can build very fast servers for other protocols". Traffic Server has been benchmarked to handle 200,000 requests per second or more (small objects out of cache). At a talk at the 2009 Cloud Computing Expo, members of the Yahoo! TS team stated that TS is used in production at Yahoo! to handle 400TB of traffic per day using only 150 commodity machines. The OStatic post describes TS as the "product of literally hundreds of developer-years".
- "PGP signature". https://trafficserver.apache.org/. Apache Software Foundation. 2015-12-16. Retrieved Jan 5, 2015. External link in
- "Traffic Server license file". Apache Software Foundation. Retrieved 2009-12-24.
- "Apache Incubator Wiki August 2009 Board reports". 2009-08-12.
- "Yahoo's Cloud Team Open Sources Traffic Server". 2009-11-02.
- "Traffic Server graduates to top-level open-source project". 2010-04-23.
- "Official project release management process". 2013-09-06.
- "The Apache Software Foundation Announces Apache Traffic Server v3.0.0 : The Apache Software Foundation Blog". 2011-06-14.
- "2009 Cloud Computing Expo". 2009-08-12.
- "Yahoo's edge services graphic". 2011-06-14. Retrieved 2011-06-14.