I have a trading algorithm coded in C# in the Quantconnect platform.
an Prop firm wants to buy it from me but he wants to test it.
But to test it I would have to give them the source code.
I don't want to give away my source code of course.
Do you have a solution to offer me?
Have been thinking more about this, why don't you create a crypto coin and then list it with an exchange, now most exchanges charge $100,000s plus but there are some that deal specifically with trading who can also create the coin, one comes to mind where you can mark to market such as USD with relevant NAV updates.
Can send you a link to an entity already doing exactly this at 3-5% and 7-10%pa returns with hourly and daily NAV updates (there are higher returns profiles using the same architecture), in turn you can provide this to the prop firm to invest, you keep 100% control of source code.
Another approach is a crypto arbitrage system which worked at 1sec, 10sec and up timeframes with 20% timeframe latency to placing the offset trades, 1-2sec at the fastest level which was converted from forex/futures arbitrage, works best on altcoins with smaller capital, it was worth $100,000s plus as it could out trade Binance, but was closed leased for 20% of that with you providing the ongoing yearly maintenance at 20% again, plus daily trading support for a fixed fee, with option to buy the source, if they lose interest you have your answer.
Obviously you lose the source code but the chance of them paying full price, say $1mil is more or less zero minus however many months you lose in the process. This is based on experience of people actually having done it like this, it's simply that one in the hand is better than two in the bush. As with all good trades, you let them come to you rather than how the rest of the world does it, chase the trade!