I'd be suspicious of permitting any online service access to my account or their ability to certify any statement of performance in a way you want it presented. A good trader would want more than a simple result like return. Did your trading cover a complete market cycle, what was the maximum drawdown are just two more of the many questions required by due diligence. If you want a third party to verify your trading results, you might try a reputable lawyer or a CPA. They will provide a letter certifying your statements of fact without revealing the details of your account data.