Bitcoin Forum

I've seen it said that online wallets are much less secure than a local client.  In particular, I've seen it said there's a risk the site owners will steal your coins.  While certainly I can believe you need to be very careful who you use, I find it difficult to believe that well-known sites such as Coinbase are going to rip their customers off.  Even a single instance would crush their reputation and likely put them out of business.

So, assuming you exercise due diligence and pay careful attention to their security measures and terms of service, is this risk truly credible?  Are there any known instances of well-established online services stealing coins or losing them to thieves?

One recent example would be TradeFortress.
https://bitcointalk.org/index.php?action=profile;u=67058

TF was originally considered as a highly-trusted member, and was the owner of Inputs.io and CoinLenders.
One day, he claimed the site Inputs.io was "hacked", and "lost" 4100+ bitcoin.
https://bitcointalk.org/index.php?topic=328053.0



List of Major Bitcoin Heists, Thefts, Hacks, Scams, and Losses
https://bitcointalk.org/index.php?topic=83794.0

We provide you with a service to track your wallets' balance: https://coinbrother.com (https://coinbrother.com)

You can easily create a paper wallet or cold storage wallet and monitor your balances safely. You just need to start your client if you want to send coins.

Nice links, thanks.

Your client will be safer, if you have your computer properly protected.
If not, then trusting something like Blockchain is probably better.  Always use 2 FA, so no one can hack your account specifically.

Any wallet whether online or on your computer is only as safe as you are. An online Blockchain.info wallet is very safe as long as you set up all the security features. Make sure to put a second password on to be able to spend you balance as this protects against keyloggers.

I prefer online wallet its so much more handy, but i think paperwallet is more secure.

remember that the easier isn't the more secure

For small amounts of BTC I'm using online wallets such as blockchain etc. For "cold wallet"ing paper wallet is basically the best option - safest thing.

I met a guy who had bought $400 worth of bitcoin and he lost them in the infamous MtGox hack. He was bummed about it and told me this when they were $11 each. Imagine how he feels now and the advice he would give you.  

Online wallet seems that is where a lot of people want to use Bitcoin

Well, for blockchain.info, you have full control of your private keys.

But, for other sites like exchanges and off-chain gambling sites, you don't even know whether the owner has already stolen part of his customers' bitcoin lol.

+1, safest and simplest options

Exchanges are different to online wallets. I wouldn't fully trust to keep my coins on an exchange for too long.