Developers | Varnish Software

Developers <3 Varnish


Technical documentation digging into the nitty-gritty of Varnish® solutions.



Let’s Encrypt with Hitch and Varnish

Securing multi-tier Varnish environments

Client SSL/TLS termination

Varnish documentation


The best community-driven Varnish® resources available, helping you do everything from getting started to solving a specific issue.



WordPress with Varnish

Adobe Experience Manager and Varnish

Varnish Web Developer FAQs

Varnish developer wiki


The latest how-tos, innovative Varnish® use cases, FAQs, news and other informative topics in blog form from the Varnish team.



10 Varnish mistakes and how to avoid them

Step-by-step: Speed up WordPress with Varnish software

Varnish and Docker: First contact

Varnish Software blog

Release notes

When things are moving, we’ll let you know!

Show all releases

Varnish Software manuals

Varnish Software™ manuals dig into the technical information and changelogs of the major Varnish® features. Here are just a few of the most popular.

Varnish Plus Cloud

Technical documentation digging into the nitty-gritty of Varnish® solutions.



Amazon Web Services

Google Cloud Platform

Microsoft Azure


Varnish High Availability

A high-performance content replicator for Varnish® that ensures maximum uptime and performance.


Varnish Cache Plus

A powerful caching engine that enables fast, resilient, high-performance content delivery under any load, at any scale.


Protect yourself against threats and vulnerabilities

New security issues appear all the time with increasing levels of sophistication. Varnish® is built with security-by-design at its heart to ensure secure end-to-end content delivery and protection against security exploits.


Varnish HTTPS support

SSL/TLS (HTTPS) encryption is, by now, a requirement for security, privacy and even SEO. With Varnish®, you can protect your client-side and backend.


Varnish Total Encryption

Varnish Total Encryption™ neutralizes entire classes of security vulnerabilities and risks, and securely encrypts all cached data using dual key AES 256 encryption.


Varnish WAF

The Varnish® Web Application Firewall (WAF) lets you inspect your HTTP traffic and detect malicious requests at the edge before they reach your web application.

Under the hood

Showing and telling are two different things.
What does Varnish look like in action?


This VCL snippet strips all the cookies that should not be kept.

We want to keep certain cookies if the req.url matches a specific condition, otherwise we will just remove all the other cookie headers.

Pre-fetch with vmod-http

Here we use a combination of vmod_kvstore (key value storage) and vmod_http (external requests).

Using these together we can prefetch content in a live streaming scenario and pace the background fetches triggered by vmod_http.

We use a “counter” function to make sure a single URL per second can trigger a prefetch request. This is to avoid overwhelming our backends. Without that counter we would push 10,000 prefetch requests to the backend.


For each incoming request we buffer the request body and try to parse it, assuming it is in JSON format.

If it is in JSON format, we extrapolate the value associated to the key “authorization”.
This is a good way to run a check on your request bodies and extend your authorization control.


Vmod-rewrite does Apache-style rewrite rules. It aims to reduce the amount of VCL to be written when many rewrites or manipulations need to be applied to URLs or headers.

A path to a file containing the rules must be specified and these will be applied at run time to every incoming request.

Does it work with…

Compatibility is key. Varnish is architecture-agnostic, caching virtually any kind of content and supporting the world’s most-used web technologies. Read up on a few of the most common CMSes, e-commerce platforms, CDNs and others that Varnish supports:

Get in touch if you have questions about all the rest.

The Varnish Book

The Varnish Book™ is really the comprehensive, nitty-gritty technical document for all things Varnish.


Get up to speed with Varnish Software. Learn more about optimizing API and web performance and content delivery.


Varnish Solutions


If you need help resolving a Varnish issue or setting things up, our support team is available to help.


Get in touch with support

Talk to an expert

Varnish experts are on hand to answer your technical questions and help you find the solution you need.


Contact us

Request a free trial