Hi HN,

I'm the creator of Bitcoinica. I'm not so established here. To be honest, I'm only 17.

Please try it out. (I can pay $1 for you if you're not willing/able to deposit, email me at info@bitcoinica.com. :-D ) You can leave any suggestions, comments, bug reports and feature requests here. I'll look through every single comment. Thanks!

This seems far more advanced than usual for Bitcoin. Nice!

I have little insight into the security of your software, but I hope you have also considered the peculiarities of Bitcoin. To name just one thing that would be far harder in a normal market: open a Bitcoinica account, deposit $10 000, buy $50 000 in Bitcoin, sell BTC really expensively at Mt Gox as the system frantically tries to rebalance. Given the volatility of BTC, this may be profitable even if[1] you subsequently abandon the Bitcoinica account (which is likely to hold $-40 000 in dollars and less than $40 000 in BTC at un-spiked prices...)

[1] EDIT: Actually, it's only profitable if you can get the Bitcoinica account into the red. But given enough ability to move the market, that's definitely possible.

I like the site. A few notes:

- Running on Heroku is not really an asset security wise. I would put something more significant to ensure users that your site is secure.

- Make sure your site is secure; it will be attacked often and by professionals. Consider hiring an expert.

- The highlighting is kind of distracting and busy.

- You should be able to access some charts and see the going rate without signing up and loggin in.

- What is a Mt. Gox Redeemable code?

- There are laws in most countries that regulate banks in regards to leverage. Have you considered any of this?

- Margin trading is risky and some people will lose more than they bargained for, expect some repercussion.

Best of luck!

A brand new financial trading platform written by a lone teenager in China? Here let me give you lots of my money! Not. :-)

Somewhat tongue in cheek. I wish you luck and admire your effort, but advise you to be humble about your skills and pay massive attention to the security aspects of your creation, and certainly engage outside experts who have much more experience in this area. Otherwise you are likely heading to a big public security/financial mishap.

The site looks great! However, what I'd really love to see in a platform is not advance trading features, but an easy way to convert USD to BTC and vice versa. I realize that this is a real challenge given the anonymity provided by the Bitcoin network and the only real instant transfer of money is through credit cards (which like to chargeback). If someone would solve this problem, you have a winner.

Very very cool! The idea is great and the interface looks slick!

However, what do you do in terms of protecting people's accounts? You say that the money is stored in your account? Gasp! How do we know you can't turn around and take all the money?

Also, what do you do to protect the accounts from a single rogue trader? If someone deposits money, margins up and loses a bunch of money, how do you protect the rest of the accounts?

I already mentioned below that I thought your site was nicely done. But you didn't answer my questions directly which makes me a bit wary.

My questions aren't site security questions per se, they deal more with the business of your site. Also, my questions are blunt, but not disrespectful, so don't be offended.

1) How do I trust you? How do I know you're not going to run away with all my money? Who are you?

Registered brokerage accounts have segregated funds, so that brokerages can't get access to my money in case the brokerage goes under. You are saying everything is in one giant account. In the case you suffer a catastrophic loss, how do I know my money is safe? Also, how do I know you're not Madoff and won't run away with all the money?

2) How are you affording the ability to margin people's accounts? Where are you getting the money?

3) You say you check for margin requirements every 5 seconds? If I were a market manipulator, I would wait for the order book on BTC to thin out, then I would massively short the markets. This would hopefully trigger massive margin calls on your end, and forced liquidation. Since the order book is thin, I would probably be able to cover at rock bottom prices. Also, presumably you (the site) would suffer tremendous losses.

How do you protect your customers from this?

Considering all the security issues with the Bitcoin ecosystem and the resulting mistrust, I think you need to be very explicit about your security.

Question for @zhoutong ...

When did you start working on this project and have the negative events (guy losing 500K, MtGox hacking, etc) of the last few months affected your development and outlook?

Site looks great. Twitter bootstrap?

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Looks pretty cool. I dislike the random pink highlighting, it's noisy. Avoid smiles, as cool as it is, you must look professional in business ;)

That said, maybe a security section would be great. eg encryption, security, independent audits, etc. Here's an example: http://help.github.com/security/

That's a great site and will help people that haven't got any trading experience to 'play' a little bit without having to do all sorts of things in the 'real' money market

A little feedback: Tooltip texts for some of the interface elements would be nice. I had to think a bit before figuring out that "P/L ($)" is supposed to be profit/loss.

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It looks great. It's good to see more things appear in the Bitcoin space.

I would add a tour page, perhaps with screenshots so people can see how it works without signing up.

Can you explain your margin fees somewhere on the site?

Thanks!

How do I logout without a logout button?

Spread seems high.