I have an address mpc1rKeaMSCuQnJevMViLuq8uWjHwgdjiV I check it via json rpc and get balance = 4.6 with 6 confirmations When I check http://blockexplorer.com/testnet/address/mpc1rKeaMSCuQnJevMViLuq8uWjHwgdjiV I get nothing.. is it OK ?
The testnet Block Explorer doesn't seem to be working. If you go to http://blockexplorer.com/testnet, the most recent block it shows is from August 29, about two weeks ago.
BTC Look's Testnet is still online. Try http://testnet.btclook.com/addr/mpc1rKeaMSCuQnJevMViLuq8uWjHwgdjiV.
There is also Blockr.io Bitcoin TESTNET
BlockStream and BlockCypher are useful:
A reasonably fast & stable testnet API I could find is Blocktrail
The Block Cypher website has a testnet blockchain explorer. https://live.blockcypher.com/btc-testnet/