CheckWriterIII 3.90 for Mac could be downloaded from the developer's website when we last checked. We cannot confirm if there is a free download of this app available.
According to the results of the Google Safe Browsing check, the developer's site is safe. Despite this, we recommend checking the downloaded files with any free antivirus software. The program lies within Business Tools, more precisely Finances. The actual developer of this software for Mac is Match Software.
From the developer:
Check Writer III+ is an application that helps you write and print checks directly from your desk, together with their accompanying letter. The check is printed with special MICR characters which will be used by banks for processing. You will also be able to reconcile transactions with your statements, to constantly have at hand your current balance.
You may want to check out more Mac applications, such as Personal Finance or Putler, which might be related to CheckWriterIII.