Whenever DiffTest starts, it invites you to register your computer to create DiffTest Pro, using a registration key made up of letters and digits.

If you have no key, DiffTest displays a line of letters and digits.  Send it by e-mail to registration@difftest.co.uk  and, provided that you have paid the appropriate licence fee, you will be sent a registration key.  When it is entered,  DiffTest Pro is generated at once.

DiffTest Pro starts immediately and runs for as long as you wish. It also allows you to print out tables of results for future reference.

Current charges for DiffTest Pro

DiffTest can be used indefinitely without charge.

A licence for DiffTest Pro on a single processor used by one person at a time costs 49 UK pounds or 69 US dollars.

A site licence for DiffTest Pro on any number of processors at a single address costs 195.00 UK pounds or 295 US dollars. 

A non-profit educational institution can get a site licence at the single-processor charge.

Personal cheques on Sterling, Euro or US Dollar accounts (may be slow)

For details of how to pay by cheque or Electronic bank transfer, send e-mail to registration@difftest.co.uk

Pay in Dollars by Credit or Debit card using PayPal

Pay in Sterling by Credit or Debit card using NOCHEX