We present a new Fortran library to evaluate all harmonic polylogarithms up to weight four numerically for any complex argument. The algorithm is based on a reduction of harmonic polylogarithms up to weight four to a minimal set of basis functions that are computed numerically using series expansions allowing for fast and reliable numerical results. Program title: Chaplin Catalogue identifier: AETC_v1_0 Program summary URL: http://cpc.cs.qub.ac.uk/summaries/AETC_v1_0.html Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 101192 No. of bytes in distributed program, including test data, etc.: 729234 Distribution format: tar.gz Programming language: Fortran 77. Computer: Computing systems on which Fortran 77 compilers are available. Operating system: Operating systems on which Fortran 77 compilers are available. Classification: 11.1. Nature of problem: Numerical evaluation of harmonic polylogarithms. Solution method: Inside the unit circle: series expansion. Outside the unit circle: inversion relations. Restrictions: Only harmonic polylogarithms up to weight four are supported. Unusual features: Allows the evaluation of HPL’s numerically for any point in the complex plane. Running time: Depending on the weight vector and argument of the HPL, between 0.2 and 400 μs.