<p>While developing products, we often need to create proprietary tools to test some of their unique features or diagnose problems.  In fact the tools can be at lest as interesting as the products themselves, and some of our internal groups have asked for copies of them.</p>

<p>So, aside from the obvious business-driven rules (<em>e.g.</em> don't retrieve sensitive data), <strong>what do you differently when you build personal or internal tools, as opposed to for-sale products, and why?</strong></p>

<p>What's more (or less) important to you in internal tools, and do you consider overall value to the company when you build them?</p>

<p>Thanks for your thoughts!</p>

From an engineering perspective, I wouldn't do anything differently:
Both internal and for-sale tools need to be well-written and well-documented
Both need to be created given a set of requirements, deadlines, budgetary restraints, etc.
Both need to be tested or validated
The one big difference I see would apply to the for-sale products as opposed to the internal tools:
for-sale products need marketing, support, etc
that internal tools can do without.
Additionally, since internal tools will be used in a somewhat more controlled environment, they don't need to be tested against different computer systems, Internet browsers, etc.