Apache Traffic Server vs Sōzu
Apache Traffic Server
trafficserver.apache.org
Sōzu
sozu.ioSide by side
| Figure | Apache Traffic Server | Sōzu |
|---|---|---|
| Price from | Free | — |
| Free plan | Yes | — |
| Free trial | — | — |
| Open source | Yes | — |
| macOS | Yes | — |
| Linux | Yes | Yes |
| API | Yes | — |
| Self-hosted | Yes | Yes |
| Plans published | 1 | 0 |
| Spec score · Reverse Proxy Software | 9.0 (#2) | 6.8 (#28) |
| Deployment | The documentation lists web proxy cache, reverse proxy, and cache hierarchy deployments. | The project publishes Linux binaries and Docker images for tagged releases and also documents building from source. |
| Installation | The project distributes source tarballs and repository code rather than project-provided binary downloads; installation uses CMake. | The project README says prebuilt binaries are available for Linux and Docker images are published for tagged releases. |
| License | ATS is distributed under the OSI-approved Apache License 2.0. | Sōzu is covered by the GNU Affero General Public License version 3.0 and above; the maker says businesses based on Sōzu should contribute back or contact Clever Cloud for a business agreement. |
| Load balancing | Layer-7 balancing supports weighted round robin and URL-consistent hashing. | It detects broken backend servers and supports Round Robin, Random, Least_loaded, and Power of two load balancing algorithms. |
| Purpose | Apache Traffic Server is a fast, scalable, extensible HTTP/1.1 and HTTP/2 caching proxy server. | Sōzu is an open-source TCP and HTTP reverse proxy built in Rust for demanding, dynamic web infrastructures. |
| Release verification | The downloads page advises verifying mirror downloads using the hash and OpenPGP compatible signature. | The project README says releases include SHA256 checksums, sigstore keyless signatures, and SLSA build provenance attestations for tarballs. |
| Security | Security options include client access controls, client authentication, SSL termination, and access control via SSL. | The project describes Rust as providing memory safety and says Sōzu workers are sandboxed, with backends shielded behind the proxy. |
Plans
In their own words
Apache Traffic Server
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.