Edit: In that case, your question makes no sense and I am voting to close it.
There's fundamentally no difference between "historical data" and >= 15 minute delay. You can write an application to stream historical data in 1:1 correspondence to the original durations to your application. I don't know any providers who queue precisely 15 minutes of market depth data to disseminate continuously at the end of every moving 15 minute interval because it makes more sense to sell that data as historical data.
While in theory CME charges no fees on a per user basis for continuous data that is delayed at least 10 minutes and not accessed indirectly over LAN, someone at the top of the hierarchy has to be paying the data distribution fees and maintaining the colocated server(s) and multicast over TCP/IP/ through which you receive the data. This has real costs.
Moreover, real-time CME market depth data is cheap (exchange fees are \$5 per month per user and a third party vendor like eSignal or IQFeed probably charges another \$50 to \$100 per month) in your case.
In other words, your question really just reduces to: "I'm in the business of selling software. Which data providers give me free historical data? I don't want to pay \$5 to \$85 per month." This is outside the scope of this QE, which is for quant professionals.
For CME, here's a few sources that sell market depth historical data on an order-by-order basis:
- CME DataMine
- Reuters tick history - sells on an instrument-by-instrument basis.
- Nanex historical data - sells on an exchange-wide basis.
For Eurex, the exchange itself also stores that data but Nanex only provides BBO:
- Eurex historical data
- Reuters tick history
You mentioned you're probably not willing to pay for your data... well, you can try your luck with Reuters or Nanex, they are more likely to cut you a special deal than the exchange itself.