FP Software

some luminaries on reddit linked a couple of sites

FP Software you can download and run.  Looks pretty comprehensive.
Here is some info from the FAQ:
' Flexible Retirement Planner models the entire retirement plan through both the accumulation and draw-down phases.  Since risk tends to compound over longer periods of time,  It is often more difficult to get a high-probability result than with a traditional planner.  

Instead of entering just one value for the whole retirement period, break it into 2 or three values, entering each one as a separate Other Expense cash flow with a given start and end year.

So rather than viewing the output of the tool as a prediction of what will happen, it’s best to view it as support for making short term decisions about what to do over the next few years.  Use the tool to guide these decisions, but revisit them often and reevaluate them in light of any new information you have.'

Another site with useful resources including calculators

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