I'd like to find a real time feed coupled with a charting service providing a real time API to the indicators used in the charts. In other words, I don't want to have to concern myself with any differences between what is seen on the charts and what the indicator API calls return.
That's not a response. I've calculated indicators myself with real time data apis. The charts must match and they don't.
This makes no sense. The API is/are the methods to access data present in the data feed! You even say YOU calculated indicators using the RT (API) data! So you have one of two problems...either YOUR calculations are wrong, -OR- your charting software (or API) is using different calculations than what you think for the particular indicators. The charting merely plots data! The data is the data. An indicator is one or more calculations using the data. The API determines what is available. You can roll your own calculations, or if available through the API, an accessible return-value (and possibly specific settings) of a pre-packaged indicator. A chart is merely a plot of the data and/or calculations.
It is true that "either YOUR calculations are wrong, -OR- your charting software (or API) is using different calculations" and that's ignoring possible differences in data feed. The point is there are a number of ways one can end up with differences between what one sees on a chart and what one sees coming out of an indicator calculation. What I'm willing to PAY for is a "no-excuses" service that lets me focus on automating manual (chart-based) trading strategies rather than trying to track down unrelated problems.
I have never heard of indicator values being delivered by API. Everybody gets data from an API and does their own algo.
What you're saying is that to guarantee identity between the chart's indicators and the algorithm's indicators, I'm going to have to develop a custom charting service utilizing my calculated indicators? I seriously doubt things are that screwed up.
What you need is a charting program with the ability to create custom code. There are several. I use SierraCharts. User code can be written in a dialect of C/C++, which in a sense, is the SierraChart user API. Note however that this SierraChart user API is not a datafeed... The data feed is separate, and SierraChart (charting and trade execution program) and the SierraChart user "API" work seamlessly with numerous compatible data feeds. As mentioned, there are several charting programs that allow custom code. The particulars are dependent on which one. The data feed is the data feed. The data is the data. The chart is merely a plot of the data and pre-packaged or user-defined calculations.
From the looks of things, I'll probably end up doing something like you suggest but it seems strange that one can't simply access the same API the charting program uses for indicators to automate trading. Here's an illustration of the problem: The white background graph is produced by a technical analysis library showing various indicators under variations on the stochastic oscillator. None of them exactly matches either of the "stoch" indicators from IB's chart. The black background IB chart shows 3 indicators, the top one has 2 of them -- the well defined k and d indicators. However, it has another "stoch" indicator at the bottom which appears to be close to the stoch d indicator but with some sort of local mean applied. None of this is documented well enough to precisely replicate IB's indicators and there is no way to call IB's indicator library with one's data stream to get the same curves.
I don't use IB so I can not offer further assist. Frankly, and I mean no offense, Im not sure that the problem isn't with your understanding of different indicators, how they are calculated, and their various settings. Anyway... IB has a large evangelical following here on ET. Maybe make a post directed at that crowd... You will definitely get answers to what you are doing, or want to do, with IB charts. Good luck