Thank you,
Can you advice block-chain explorer like bitcoind or online service with open API ?
Check out BlockTrail's Block Explorer
here.
We also provide a wide range of API's for your app, you can find more information on that
here and a technical blog post about with all we offer
here.
Oh and btw, we have a fair usage policy in place for our API's and SDK's, so you can have peace-of-mind that you won't ever need to pay for our services.
Let me know if you need some assistance in anything