Introduction

OpenLiteSpeed (OLS) is a high-performance, open-source web server. It serves as a free alternative to LiteSpeed Web Server Enterprise and provides compatibility with Apache rewrite rules.

OLS uses an event-driven architecture and includes a built-in caching engine (LSCache).

Overview

OpenLiteSpeed supports modern protocols including HTTP/2 and HTTP/3 (QUIC). It is suitable for standalone servers, development environments, and production use, particularly for individual sites or environments that prefer an open-source solution under the GPLv3 license.

Features

Protocols and compatibility

• HTTP/1.0, HTTP/1.1, HTTP/2, and HTTP/3 (QUIC)
• GZIP and Brotli compression
• WebSocket proxying
• IPv4 and IPv6 support
• Unlimited IP-based and name-based virtual hosting
• HTTPS with OCSP stapling
• Support for PHP, Perl, Ruby, Python, and other scripting languages via LSAPI, CGI, FastCGI, and other interfaces

Performance and scalability

• Event-driven architecture
• Low memory usage
• High concurrent connection capacity
• sendfile() and asynchronous I/O
• LiteSpeed Server Application Programming Interface (LSAPI) for dynamic content
• Built-in LSCache for dynamic page caching
• .htaccess rewrite rule support (requires restart to apply changes)

Apache compatibility

• Support for Apache mod_rewrite rules
• Compatible with many common Apache rewrite configurations

Security

• Connection and bandwidth throttling
• mod_security v3 compatibility
• Protection against common SSL attacks
• Strict HTTP request validation and buffer overrun prevention
• suEXEC support
• Chroot support

Management

• WebAdmin Console for configuration and real-time monitoring
• Virtual host templates
• Support for multiple PHP versions
• Real-time statistics
• LiteSpeed Prometheus Exporter

Additional features

• MP4/FLV streaming
• Geo-IP lookup
• Custom logging