Apache Traffic Server vs Varnish Cache
A side-by-side comparison of two self-hosted reverse proxy & gateways options — licensing, setup difficulty, resource needs, and what each one replaces.
| Feature | Apache Traffic Server | Varnish Cache |
|---|---|---|
| Deploy effort | Under-an-hour setup | Under-an-hour setup |
| Health score | 82 · Excellent | 15 · At risk |
| Status | Actively maintained | Archived |
| Category | Reverse Proxy & Gateways | Reverse Proxy & Gateways |
| License | Apache-2.0 | BSD-2-Clause |
| Language | C++ | C |
| Setup difficulty | Hard | Hard |
| Min. RAM | 512 MB | 256 MB |
| Deployment | docker, binary, bare-metal | docker, binary, bare-metal |
| GitHub stars | ★ 1,987 | ★ 4,045 |
| First released | 2009 | 2006 |
| Replaces | Varnish, Squid | Cloudflare, Squid |
What are Apache Traffic Server and Varnish Cache?
Apache Traffic Server
Apache Traffic Server is a high-performance, scalable caching proxy server used as a forward and reverse proxy. It was originally developed by Inktomi and later donated to Apache.
- Forward and reverse caching
- High concurrency
- Plugin API
- HTTP/2 and TLS support
Varnish Cache
Varnish Cache is a powerful HTTP accelerator that sits in front of web servers to cache content and dramatically speed up delivery. Its VCL language gives fine-grained control over caching.
- Powerful HTTP caching
- VCL configuration language
- Massive throughput
- Edge-side includes
Apache Traffic Server vs Varnish Cache: key differences
The biggest difference is maintenance: Varnish Cache's repository is archived and no longer developed, while Apache Traffic Server is actively maintained. Apache Traffic Server is written in C++, while Varnish Cache is built with C. Licensing differs — Apache-2.0 for Apache Traffic Server versus BSD-2-Clause for Varnish Cache. Varnish Cache is the lighter option, starting around 256 MB of RAM against 512 MB for Apache Traffic Server. Varnish Cache is the more established project (first released 2006), while Apache Traffic Server arrived in 2009. Varnish Cache has the considerably larger community, at 4,045 GitHub stars versus 1,987.
Why pick each one
Choose Apache Traffic Server if…
- Released under the Apache-2.0 license
- First-class Docker support for quick deployment
- Active community (2k GitHub stars)
- Written in C++
Choose Varnish Cache if…
- Released under the BSD-2-Clause license
- First-class Docker support for quick deployment
- Active community (4k GitHub stars)
- Written in C
Frequently asked questions
Is Apache Traffic Server or Varnish Cache better?
Neither is universally better. Varnish Cache has the larger community; both share a hard setup difficulty, so the decision comes down to features and licensing.
Are Apache Traffic Server and Varnish Cache free and open-source?
Yes. Apache Traffic Server is licensed under Apache-2.0 and Varnish Cache under BSD-2-Clause. Both can be self-hosted at no software cost.
Can I run Apache Traffic Server and Varnish Cache with Docker?
Apache Traffic Server: yes. Varnish Cache: yes.
Which is lighter on resources, Apache Traffic Server or Varnish Cache?
Varnish Cache has the smaller minimum footprint at 256 MB of RAM, compared to about 512 MB for Apache Traffic Server. Real-world usage depends on library size, user count, and enabled features.