LiteSpeed Web ServerFeature explanations

Features, explained.

LiteSpeed Web Server is packed with features. Here's what each one does for your sites — grouped by category, with links to deeper pages where available.

All Features See Pricing

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LiteSpeed Web Server

Basic Features

15 features

#HTTP/3

HTTP/3 is the newest version of HTTP and runs over QUIC instead of TCP. LiteSpeed shipped one of the first production-ready implementations and enables it by default, giving visitors faster connections and better performance on unreliable networks.

#QUIC

QUIC began as a Google project to carry HTTP encrypted over UDP. The IETF later standardised it, splitting the work into the QUIC transport and the HTTP/3 application protocol. LiteSpeed's own open-source QUIC library, LSQUIC, powers its implementation.

#HTTP/2

LiteSpeed was among the first commercial servers with full HTTP/2 support: a binary, fully multiplexed protocol with header compression that loads pages over a single connection.

#HTTP 1.0/1.1

A fully HTTP/1.1-compliant server with HTTP/1.0 backwards compatibility, including chunked transfer encoding, basic and digest authentication, entity tags and range / multi-range requests.

#Scripting languages

Dynamic content in PHP, Perl, Ruby, Python and Java runs as external applications, connected to the server through several server APIs such as LSAPI, FastCGI, CGI, AJP and proxy.

#Server APIs

LiteSpeed talks to external applications through LSAPI, CGI, FastCGI, AJPv13 and reverse proxy. LSAPI — LiteSpeed's own interface — is the fastest and most efficient option for PHP, Ruby and Python.

#HTTPS

Modern TLS (including TLS 1.3) with SNI, OCSP stapling and settings that make PCI compliance straightforward.

#IPv4 and IPv6

Listeners can serve both IPv4 and IPv6 traffic.

#Virtual hosting

Host an unlimited number of IP-based and name-based virtual hosts (subject to your license's domain limit).

#Concurrent connections

Current Free Starter, Site Owner and Web Host licenses place no limit on concurrent connections — and the event-driven core can sustain hundreds of thousands of them, far beyond what process-based servers can handle before running out of memory.

#Brotli compression

Brotli is a lossless compression algorithm that produces smaller files than gzip and speeds up page loads. It is enabled by default.

#GZIP compression

Compress responses on the fly — and cache the compressed copies — to save bandwidth for clients without Brotli support.

#SPDY support

Legacy SPDY 2, 3 and 3.1 support, the predecessor of HTTP/2, for older clients.

#WebSocket proxying

Proxy WebSocket connections to backend applications while keeping LiteSpeed's performance and security controls — and serve other content on the same page.

#Operating systems

LiteSpeed Web Server runs on Linux and FreeBSD, with historical builds for macOS and Solaris.

Security

15 features

#Server-level reCAPTCHA

When load spikes or a client looks suspicious, LiteSpeed can present a reCAPTCHA challenge at the server level — stopping layer-7 floods before they reach your application.

#Session tickets & key rotation

TLS session tickets speed up returning visitors, and keys are rotated automatically to preserve forward secrecy.

#Secure WebSocket backends

Proxy to WebSocket backends over encrypted connections.

#Firewall-level bot blocking

Robots detected as abusive can be blocked at the firewall so they no longer consume web server resources.

#Anti-DDoS with ConfigServer / iptables

LiteSpeed can hand offending IPs to ConfigServer Firewall (CSF) or iptables, blocking attacks at the network layer.

#Connection and bandwidth throttling

Per-IP limits on connections, requests and bandwidth. Clients that exceed them are slowed or blocked before they can overwhelm the server.

#Asynchronous ModSecurity

LiteSpeed supports almost all ModSecurity features and processes rule sets asynchronously for maximum efficiency. Compatibility is updated continuously as popular rule sets evolve.

#Atomicorp support

Officially supported by Atomicorp for Atomic Secured Linux and its Realtime ModSecurity Rules — one of the longest-running commercial rule sets.

#SSL BEAST & renegotiation protection

LiteSpeed responds quickly to new TLS attack vectors, shipping updates and settings that neutralise attacks such as BEAST and insecure renegotiation.

#HTTP request checking

Every request is validated. Paths that try to reach hidden files are rejected, and maximum URL, header and body sizes can be enforced to stop malformed traffic.

#Buffer-overrun protection

Designed to guard against buffer-overrun attacks, with extra fail-safes that prevent exploitation even if a bug is found.

#suEXEC

Run PHP, Ruby, CGI, FastCGI and LSAPI applications as the owning user, so one compromised account can't touch another.

#CageFS compatibility

A close partnership with CloudLinux means full compatibility with CageFS, keeping each user inside their own virtualised file system.

#chroot ability

Place a single application, a virtual host or the whole server in a chroot jail, limiting what an attacker could reach if something is compromised.

Performance & Scalability

24 features

#Event-driven architecture

Apache creates a process or thread for every connection, which is expensive. LiteSpeed's event-driven design handles thousands of connections in a handful of processes, keeping CPU and memory use low even under heavy load.

#Massive concurrency

The efficient event loop lets a single server hold hundreds of thousands of concurrent connections — far more than a process-based server could before exhausting RAM.

#POST request caching

Selected POST requests can be cached, useful for API-style endpoints that return the same result for the same input.

#TLS certificate compression

Compressing certificates in TLS 1.3 handshakes reduces bytes on the wire and speeds up connection setup.

#SSL acceleration

TLS record-level optimisation and efficient encryption deliver HTTPS pages up to three times faster than Apache.

#Fast handshakes & offload

Optimised TLS and QUIC handshakes, with offloading, cut the time before the first byte arrives.

#Tiny memory footprint

Using far less memory than Apache leaves more RAM for PHP and databases, resulting in a faster, more stable server.

#sendfile()

The zero-copy sendfile() system call greatly reduces CPU use when serving large static files.

#Asynchronous I/O

Asynchronous I/O lets other work continue while a transfer completes, reducing latency. Available in LiteSpeed Enterprise.

#LiteSpeed server API (LSAPI)

LiteSpeed's exclusive server API for PHP, Ruby and Python. Optimised code and native configuration give dynamic applications a large performance advantage over other interfaces.

#Shared-hosting PHP

suEXEC Daemon mode forks PHP processes from a running parent instead of starting new ones, which is much faster and lets users share an opcode cache safely.

#suEXEC for different needs

Worker mode for limited resources and custom php.ini, Daemon mode for speed with light resource use, and ProcessGroup mode for per-user opcode caching.

#High-performance static content

The event-driven core serves static requests many times faster than Apache, especially at high traffic.

#High-performance dynamic content

LSAPI handles web applications far more efficiently than other interfaces, so PHP, Ruby and Python apps respond much faster.

#HTTPS performance

Efficient TLS handling serves HTTPS content around three times faster than Apache.

#OCSP stapling

Attaches the certificate's revocation status to the TLS handshake, removing a lookup from the client's critical path.

#LSCache

A full-featured page cache built into the server — comparable to Varnish but with no extra layer — controlled by application plugins or rewrite rules and included with every license.

#ESI support

Edge Side Includes split a page into separately cached pieces, so pages with private blocks can still be served from cache.

#.htaccess caching

Apache checks every directory for .htaccess files on each request. LiteSpeed caches them, keeping full .htaccess support without the performance penalty.

#CloudLinux LVE compatibility

Full compatibility with CloudLinux's Lightweight Virtual Environment for per-account resource limits.

#More scalable applications

A smaller server footprint leaves more RAM for applications, and LSAPI delivers faster responses — so the same hardware serves more users.

#Web application buffering

Dynamic requests are delegated to external application processes while the server keeps handling other connections, buffering requests and responses for smooth throughput.

#Just-in-time configuration

Virtual host configurations are parsed the first time each site is requested rather than at startup, dramatically cutting restart time on servers with many sites.

#CPU affinity

Binding processes to specific CPU cores improves cache efficiency and throughput.

High Availability

04 features

#Redis vHost high availability

Dynamic virtual host definitions stored in Redis can be served from a highly available Redis setup, so mass-hosting configurations stay online.

#Apply changes with zero downtime

Graceful restarts let existing requests finish on old processes while new processes pick up the new configuration immediately.

#Zero-downtime upgrades

Upgrades use the same graceful mechanism: new processes with the upgraded software start while old ones finish their work.

#Instant recovery

If a server process exits unexpectedly, a new one is created automatically to take over.

Apache Compatibility

04 features

#Apache configuration files

LiteSpeed runs from Apache's httpd.conf and .htaccess files. There's nothing to reconfigure — your existing settings are simply processed by a faster architecture.

#Control panels

Works with control panels written for Apache. Plugins for cPanel, Plesk and DirectAdmin — plus InterWorx's own plugin — make switching a one-click job.

#Full .htaccess support

.htaccess files are read automatically and cached, so you get Apache compatibility without Apache's .htaccess slowdown.

#Apache modules

Compatible with Apache core module functionality including mod_rewrite, mod_security, mod_include and mod_cache directives.

Ease of Use

06 features

#Dynamic virtual hosts

Define virtual hosts on the fly from a Redis backend or with rewrite rules — ideal for mass hosting.

#Control panel plugins

Plugins for cPanel/WHM, Plesk and DirectAdmin let you install, switch, upgrade and manage caching from the panel you already use.

#cPanel support

cPanel officially supports LiteSpeed Web Server through its ticket system.

#WebAdmin console

A browser-based console puts every configuration option within reach, making LiteSpeed far easier to manage than config-file-only servers.

#Virtual host templates

Templates make it easy to create and maintain many virtual hosts with consistent settings.

#Real-time statistics

Watch live traffic, connections and cache performance in the WebAdmin console to diagnose problems and spot attacking IPs.

Advanced Features

10 features

#Native application support

Configure Ruby, Python and Node.js applications natively in LiteSpeed — no Passenger module required.

#Up-to-date HTTP/3

LiteSpeed tracks the latest QUIC and HTTP/3 developments closely, shipping improvements quickly.

#Namespace containers

Run applications in controlled, sandboxed environments using Linux namespaces (with Bubblewrap support) for stronger isolation.

#Multiple PHP versions

Run several PHP versions side by side, so each site or user can choose the version it needs.

#FrontPage Server Extensions

Legacy support for Microsoft FrontPage Server Extensions 2002 for UNIX.

#Geo-IP lookup

Identify visitors' locations by IP to customise content or access rules.

#External logger

Pipe logs straight to a database, a log processor or a remote server.

#Custom log formatting

Customise request logs using syntax compatible with Apache's mod_log_config.

#Load balancing

Balance traffic across backend servers or application instances. For clusters, see LiteSpeed Web ADC.

#Video streaming

Pseudo-streaming for mp4 (H.264) and flv video files.

CloudLinux Compatibility

06 features

#Lightweight Virtual Environment (LVE)

LVE is kernel-level, container-based resource isolation that ensures no single site can bring down the server.

#CageFS

CageFS gives every user a virtualised file system and toolset, so they only see their own files — including in shell sessions.

#PHP Selector

CloudLinux PHP Selector works with LiteSpeed's LSPHP, letting users switch PHP versions from the same familiar interface.

#Node.js Selector

Users can run Node.js applications (such as Ghost) that LiteSpeed proxies to, with versions chosen through the Node.js Selector.

#Python & Ruby Selector

Users choose the exact Python or Ruby version their application needs.

#CRIU

CRIU saves a running process to disk and restores it later, so frequently used PHP processes start almost instantly.

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