Web accelerator

A web accelerator is a proxy server that reduces web site access times. They can be a self-contained hardware appliance or installable software.

Techniques

Web accelerators may use several techniques to achieve this reduction:

• They may cache recently or frequently accessed documents so they may be sent to the client with less latency or at a faster transfer rate than the remote server could.
• They may freshen objects in the cache ensuring that frequently accessed content is readily available for display.
• They may preemptively resolve hostnames present in a document (HTML or Javascript) in order to reduce latency.
• They may prefetch documents that are likely to be accessed in the near future.
• They may compress documents to a smaller size, for example by reducing the quality of images or by sending only what's changed since the document was last requested.
• They may optimize the code from certain documents (such as HTML or Javascript).
• They may filter out ads and other undesirable objects so they are not sent to the client at all.
• They may maintain persistent TCP connections between the client and the proxy server.

Location

Web accelerators may be installed on the client (browsing) computer / mobile device or on ISP hosted servers or both. Accelerating delivery through compression requires some type of host based server to collect, compress and then deliver content to a client computer.

Client-Server

There may be two sections to the proxy as well - a server portion sits in front of the Web server and captures the input and output from the server and a client portion sits in front of the end-users Web Browser to capture the input and output from the browser.

Client Side

As of July 2006, these applications generally serve to improve dial-up, broadband and other connections from which users may not be getting the best speed. Many users can achieve a 2- to 10-times speed increase in average browsing experience, while some report a 5- to 20-times speed increases for specific web sites and pages. Many ISPs offer web accelerators as a part of their dial up and broadband services. Web accelerators are typically designed for web browsing and, sometimes, for e-mailing and can not improve speeds of streaming, gaming, P2P downloads or many other Internet applications. However, there is substantial work being done on client-side Web Accelerators for Application Delivery Networks by several companies including Cisco Systems and F5 Networks as the demand for SaaS and PaaS look set to grow among SMEs.

Server Side

Other web accelerators are targeted at the web site or web application owners. This type of web accelerator is installed in front of web servers and application servers and use a variety of the above techniques to improve performance to all users accessing the accelerated web sites or web applications. Sometimes referred to as a Reverse proxy.

These type of server side accelerators has the added benefit of off-loading transactions and connection managements from the web or applications servers and hence, reducing its CPU utilisation and increasing web server or application scalability to handle more users with less bandwidth.

Most Popular

Since there are so many different PC configurations, it is impossible for any one web accelerator to be the best as an application of its purpose. It is even possible for a web accelerator to slow down and clog up a connection.

Comparison

	Compression	Operating system	Browser	Caching	Prefetching	Optimize code	Preemptive hostname resolution	Ad removal	Client	Connection	Price
aiCache	Gzip	Linux	All	Yes	Yes	Yes	Yes	Yes	All	High Speed	Commercial
CACHEbox	None	Appliance (Linux)	All	Yes	Yes	No	No	Yes	End user, ISP	Broadband, Satellite, Wireless, Fiber, DSL	Commercial
CProxy	Gzip, images	Windows	All	Yes	?	Yes	Yes	Yes	user	up to 756kbps	Free demo, full version 35USD per year
FasterFox	None	Windows, Mac, Linux and Mobile devices	Firefox	Yes	Yes	No	No	No	user	Dialup, Wireless, Broadband, DSL	Free
fasTun	Images, text & any gzippable data	Any	Any	No	No	HTML CSS	Yes	Yes	All	Any	Free
Freewire	Images and email attachments	Windows, except NT and 95	Internet Explorer 5.0 or higher	?	?	No	No	No	ISP	Dial-up	local rate
Google Web Accelerator	Yes	Windows	Explorer, Firefox	Yes	Yes	No	No	No	user/Google server	Broadband	Free
Netfury	Images, Text, Email, HTTP downloads	Windows, Mac	Explorer, Firefox, Opera, Netscape	Yes	No	No	No	No	End User, ISP	Dial-up, Broadband, DSL, ISDN, Satellite, Wireless	£24.99
Nitro	Images, Text, Email, HTTP downloads	Windows, Mac	Explorer, Firefox, Opera, Netscape	Yes	Yes	No	No	No	End User, ISP	Dial-up, Broadband, DSL, ISDN, Satellite, Wireless	$29.95 a year
ONSPEED	Text & Images & Flash & Office Docs	Windows, Mac and Mobile devices	Any	No	No	No	No	No	user	Dialup, Wireless, Broadband, DSL	$49.99 (US) £24.99 pa Free (for users of BT Yahoo! Dialup Internet in the UK)
Propel	Images, Text, Email, PDF, HTTP downloads	Windows, Mac	Explorer, Firefox, Opera, Netscape	Yes	No	No	No	No	End User, ISP	Dial, DSL, ISDN, Satellite, wireless	$44.95 US per year. Free with many ISP subscriptions
Proxyconn Web Accelerator	Text & Images & Flash & Office Docs	Windows, Mac, Mobile devices	Any	Yes	Yes	No	No	No	user	Dialup, Wireless, Broadband, DSL	$47.88 Yearly or $5.95 Monthly
RabbIT	Images, text & any gzippable data	Unix (Linux, *BSD, others), Windows, Mac (generally every system with Java 1.6 VM available)	Any	Yes	No	No	No	Yes	ISP	Any	Free
SiteCelerate	Text & Images	?	Any	Yes	Yes	No	No	No	user/ISP	Any	Per CPU
Squid	Text & Images	?	Any	Yes	Yes	Yes	Yes	Yes	user/ISP	Any	Per CPU
Toonel	Text & Images	Windows, Linux, Mac OS, Symbian, WindowsMobile	Any	No	No	No	No	No	user/ISP	Any	Free
Varnish	?	Unix (Linux, *BSD, Mac OS X, others)	Any	?	?	?	?	?	?	Any	Free
Ziproxy	Images, text & any gzippable data	Unix (Linux, *BSD, Mac OS X, others)	Any	No	No	HTML Javascript CSS	Yes	Yes	ISP	Any	Free

External links

• Web Accelerators at the Open Directory Project
• web application acceleration from aiCache
• web application acceleration tools from Akamai