TROLL — Tandem Repeat Occurrence Locator. Summary: Tandem Repeat Occurrence Locator (TROLL), is a light-weight Simple Sequence Repeat (SSR) finder based on a slight modification of the Aho–Corasick algorithm. It is fast and only requires a standard Personal Computer (PC) to operate. We report running times of 127 s to find all SSRs of length 20 bp or more on the complete Arabdopsis genome—approx. 130 Mbases divided in five chromosomes—using a PC Athlon 650 MHz with 256 MB of RAM. Availability: TROLL is an open source project and is available at