Sonatina, formally the Sonatina Symphonic Orchestra (SSO), is a free, open-source library of sampled orchestral instruments distributed in SFZ format. It was originally created by Swedish composer Mattias Westlund in 2011 and has been maintained and expanded by developer Peter Eastman since 2017. The library is released under the Creative Commons Sampling Plus 1.0 license and draws on public-domain and CC-licensed source material, including samples from the University of Iowa Musical Instrument Samples and the Philharmonia Orchestra sample set.

SSO covers the standard orchestral sections — strings (violins, violas, cellos, basses), brass (trumpets, French horns, trombones, tuba), woodwinds (flutes, oboes, clarinets, bassoons), and percussion and keyboards (timpani, piano, harp, organ) — with multiple articulations such as sustain, marcato, staccato, legato, and pizzicato. Most instruments are sampled in minor thirds, with short articulations using round-robin layers. The samples are stereo 16-bit/44.1 kHz WAV or FLAC files, intended for use with free SFZ players such as Sforzando and sfizz, though the patches can also be loaded into Kontakt or HISE via community conversions.

The library is widely used by hobbyist composers, game developers, and notation users looking for a lightweight, royalty-free orchestral palette, and is often cited as a starting point for virtual orchestration because it can be redistributed inside open-source projects and free games.

Sonatina has 4 products cataloged on Equipboard, including Virtual Instrument and Sampler Plugins. Their gear is featured by 1 artist, with the strongest followings in Electronic. Notable users include IBRANOVSKI.