This dataset is based on work from the University of Berkeley Personality Lab, under the direction of Oliver P. John; a link active in mid-July 2018 is here.
A Lertap-ready workbook for Excel, found under "Downloads", has been created by copying data from the BFI data file that accompanies the psych package developed by William Revelle at Northwestern University.
"BFI" means "Big Five Inventory". "BFI-25", as used here, refers to a 25-item subset of selected BFI items, having five items for each of five BFI scales: "Agreeableness", "Conscientiousness", "Extroversion", "Neuroticism", and "Openness".
A codebook for the data is available here.
Comments on scoring the items, as originally seen in documentation for the psych package, are here. Note that the Lertap-ready dataset, available via the next page, incorporates the scoring codes so that they're ready for use by Excel.
This document has sample output created by running one of the five-item scales, "Neuroticism", through Lertap, Xcalibre, and two R packages: psych, and ltm.