Features: very fast - performance is the primary goal; headers only; no dependencies - just copy and use; call style using the excellent cppformat library; ostream call style is supported too; optional extremely fast asynchronous mode - using lockfree queues and other tricks to reach millions of calls/sec; custom formatting; multi/single threaded loggers; easily extendable with custom log targets (just implement a single function in the sink interface). severity based filtering - threshold levels can be modified in runtime as well as in compile time.

various log targets: rotating log files, daily log files, console logging, linux syslog.