Access-based

Early systems for managing LETS were based on Dos, for example QLETS written by Chris Hohner, which included a charge-simulation facility to allow systems to determine the effects of different charging systems (e.g. per transaction, annual fees, demurrage) and who later produced the Perl LETS-Webtool.
Later on several systems became available which were based on Access, which is the database that comes with Microsoft Office, and is thus widely available. Proprietary Access-based systems were LOIS in the UK and LETSAssist in Australia and NZ. In the US, Kent Gordon's Timekeeper, was used by the Timedollars organisation for several years.
In the UK, Nikki Locke's opensource system, written for Oswestry & District LETS (odLETS), whilst not supported, has been made freely available LETS groups, and may still be appropriate for cheque-based schemes where transactions are managed at a single point. You can download it from http://www.trumphurst.com/odlets/letsdb.zip
We suspect that a number of different LETS organisers may have evolved their own management systems, based on Access. John Hall, of Kingston-upon-Thames LETS (KutLETS) has developed a way of writing from Access to web, and this is a way of making the transition from an online to a web-based system.