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Apache Traffic Server

trafficserver.apache.org

Free plan Open source macOSLinuxAPISelf-hosted
Visit trafficserver.apache.org
Spec score 9.0 #2 of 35 in Proxy Software

What it is

Apache Traffic Server is a free, open-source caching proxy server for HTTP/1.1 and HTTP/2. It stores frequently requested pages, images, and web service calls so they can be reused, with the stated aims of improving response time and reducing server load and bandwidth needs. It can also add keep-alive behavior, filter or anonymize requests, and balance traffic through a proxy layer. Deployment patterns include web proxy cache, reverse proxy, and cache hierarchy. As a layer 7 HTTP load balancer, it can choose next-hop servers using request attributes, weighted round robin, or URL consistent hashing. Plug-in APIs let teams add behavior such as changing headers, handling ESI requests, or implementing cache algorithms. Security options include client access controls and authentication, SSL termination, and SSL-based access control. It is self-hosted, with Linux and macOS listed as platforms. The project identifies enterprises, internet service providers, backbone providers, and large intranets as its intended audience. The listed stable release is 10.2.0; 9.2.15 is listed as the long-term support release.

Spec sheet

What it does
Apache Traffic Server is a fast, scalable and extensible HTTP/1.1 and HTTP/2 caching proxy.Read 21 Oct 2026 · trafficserver.apache.org
Purpose
Apache Traffic Server is a fast, scalable, extensible HTTP/1.1 and HTTP/2 caching proxy server.Read 9 Oct 2026 · trafficserver.apache.org
Audience
The documentation says Traffic Server is designed for enterprises, internet service providers, backbone providers, and large intranets.Read 9 Oct 2026 · docs.trafficserver.apache.org
Deployment
The documentation lists web proxy cache, reverse proxy, and cache hierarchy deployments.Read 9 Oct 2026 · docs.trafficserver.apache.org
Security
Security options include client access controls, client authentication, SSL termination, and access control via SSL.Read 9 Oct 2026 · docs.trafficserver.apache.org
Support
Users can seek help through the Users Mailing List or ASF Slack, and code questions through the developers discussion list.Read 9 Oct 2026 · trafficserver.apache.org
License
ATS is distributed under the OSI-approved Apache License 2.0.Read 21 Oct 2026 · apache.org
Cache architecture
The cache indexes objects by URL and headers, supports alternate cached versions, RAM caching and partitioned storage, and can continue as a proxy when cache disks fail.Read 21 Oct 2026 · docs.trafficserver.apache.org
Caching
It caches and reuses frequently requested pages, images and web-service calls to reduce response time, origin load and bandwidth.Read 21 Oct 2026 · trafficserver.apache.org
Cloud integrations
The origin-authentication plugin supports Amazon S3 and Google Cloud authentication.Read 21 Oct 2026 · docs.trafficserver.apache.org
Current releases
The page lists 10.2.0 as the latest stable release and 9.2.15 as the long-term support release with security fixes and critical updates.Read 9 Oct 2026 · trafficserver.apache.org
Deployment modes
Documentation covers explicit and transparent forward proxying, reverse proxying, parent-child cache hierarchies and layer-7 HTTP load balancing.Read 21 Oct 2026 · docs.trafficserver.apache.org
DNS
ATS includes an asynchronous DNS resolver and a host database tracking DNS, HTTP version and origin reliability.Read 21 Oct 2026 · docs.trafficserver.apache.org
Documentation
The manual includes getting-started material, administrator and developer guides, API reference, configuration, monitoring, troubleshooting, FAQ and command-line appendices.Read 21 Oct 2026 · docs.trafficserver.apache.org
Documentation limitation
The developer guide is described as a work in progress and contains sections referring to removed functionality from an older commercial version.Read 21 Oct 2026 · docs.trafficserver.apache.org
Extensibility
Its plug-in APIs allow custom behavior such as modifying HTTP headers, handling ESI requests, or implementing a cache algorithm.Read 9 Oct 2026 · trafficserver.apache.org
Funding model
The foundation is funded by individual donations and corporate sponsors.Read 21 Oct 2026 · crunchbase.com
Installation
The project distributes source tarballs and repository code rather than project-provided binary downloads; installation uses CMake.Read 21 Oct 2026 · docs.trafficserver.apache.org
Latest release news
The home page lists security releases v10.2.1, v10.1.5 and v9.2.16 dated October 20, 2026.Read 21 Oct 2026 · trafficserver.apache.org
Limit: documentation and monitoring
Reviewers say documentation can be hard to understand and request better Grafana/Prometheus monitoring visibility.Read 21 Oct 2026 · g2.com
Limit: learning curve
Reviewers report complicated configuration, a steep learning curve and difficulty managing the system after initial setup.Read 21 Oct 2026 · g2.com
Limit: startup and cache behavior
One reviewer reports caching lags and extra startup time for newcomers, with solutions sometimes taking considerable time to find.Read 21 Oct 2026 · g2.com
Limit: support responsiveness
Several reviewers report that support responses to problems or reports can take a long time.Read 21 Oct 2026 · g2.com
Load balancing
Layer-7 balancing supports weighted round robin and URL-consistent hashing.Read 21 Oct 2026 · docs.trafficserver.apache.org
Maker founded
The Apache Software Foundation was established in 1999.Read 21 Oct 2026 · linkedin.com
Maker headquarters
LinkedIn lists the foundation headquarters as Wilmington, Delaware.Read 21 Oct 2026 · linkedin.com
Maker legal name
The Apache Software Foundation is listed as the legal nonprofit organization behind Apache projects.Read 21 Oct 2026 · crunchbase.com
Maker size
LinkedIn lists the foundation in the 5,001–10,000 employee range.Read 21 Oct 2026 · linkedin.com
Management API
ATS provides a JSON-RPC 2.0 administration endpoint plus traffic_ctl command-line management.Read 21 Oct 2026 · docs.trafficserver.apache.org
Performance
The project says ATS scales on modern SMP hardware and handles tens of thousands of requests per second.Read 21 Oct 2026 · trafficserver.apache.org
Plugin capabilities
Built-in plugins cover authentication, background fetch, cache-key manipulation, ESI, failover, compression, header rewriting, health checks, statistics, regex remapping, static hits, WebP conversion and debugging.Read 21 Oct 2026 · docs.trafficserver.apache.org
Plugin languages
Plugins can be written in C++ or Lua; plugin callbacks can filter, deny, authorize or transform HTTP transactions and add protocol support.Read 21 Oct 2026 · docs.trafficserver.apache.org
Plugins
A consistent C API lets developers move functionality into plugins without changing the core.Read 21 Oct 2026 · docs.trafficserver.apache.org
Praise: deployment
Reviewers describe installation and initial setup as easy or lightweight and praise documentation and Apache community support.Read 21 Oct 2026 · g2.com
Praise: extensibility
Reviewers praise remap rules, plugins, regex matching, API extensibility and rate-limiting options.Read 21 Oct 2026 · g2.com
Praise: performance and caching
G2 reviewers repeatedly praise speed, scalability, high-volume handling, caching efficiency and reduced origin-server load.Read 21 Oct 2026 · g2.com
Protocols
The project site states full support for HTTP/1.1 and HTTP/2, with ongoing development for emerging web standards and protocols.Read 9 Oct 2026 · trafficserver.apache.org
Proxying
Proxy features include keep-alive, filtering or anonymizing requests and load balancing through a proxy layer.Read 21 Oct 2026 · trafficserver.apache.org
Rating on G2
4.1 out of 5 from 17 reviewsRead 21 Oct 2026 · g2.com
Release scale
ATS 10.2 development included 1,039 commits, 655 pull requests and 44 contributors.Read 21 Oct 2026 · docs.trafficserver.apache.org
Release verification
The downloads page advises verifying mirror downloads using the hash and OpenPGP compatible signature.Read 9 Oct 2026 · trafficserver.apache.org
Scale
The project says major CDNs and content providers use it for multiple terabits per second of traffic.Read 21 Oct 2026 · trafficserver.apache.org
Security controls
Security documentation covers IP allowlists, TLS termination on both client and origin connections, mutual TLS, certificate verification, rotating TLS ticket keys, OCSP stapling and split DNS.Read 21 Oct 2026 · docs.trafficserver.apache.org
Security release
A July 2026 advisory reported 34 fixed vulnerabilities, including memory-safety, denial-of-service, request-smuggling, access-control, SSRF and disclosure issues, with a maximum CVSS of 10.Read 21 Oct 2026 · trafficserver.apache.org
System requirements
Build requirements include CMake, Ninja, pkg-config, GCC or Clang, OpenSSL, PCRE, libcap, flex, hwloc, Lua, curses and curl, with platform-specific packages for Linux, Alpine, macOS and FreeBSD.Read 21 Oct 2026 · github.com

Plans and prices

Apache Traffic Server Free No price or usage limits stated on the opened pages Read 9 Oct 2026 · trafficserver.apache.org

Every Apache Traffic Server plan and price →

Strong points and limits

Strong points

  • Free and open source
  • Supports HTTP/1.1 and HTTP/2
  • Offers reverse proxy and cache hierarchy deployments
  • Includes SSL termination and access controls
  • Plug-in APIs support custom behavior

Limits

  • Self-hosted deployment
  • The listed stable release is 10.2.0
  • Downloads should be verified with hash and signature

Who it suits

It suits enterprises, internet service providers, backbone providers, and large intranets that need a self-hosted HTTP caching proxy or load balancer. Teams can extend its behavior through plug-in APIs.

Verdict

Apache Traffic Server combines caching, proxying, and layer 7 load balancing with configurable plug-ins. It is free to use, but deployment and operation are self-hosted.

Where Specifiction places it

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