user78: Input: any old Bitcoin address e.g. 
1BCNEPySL4gzzjg8NNyNsQYJWYmZwpgaPF
Output: the FirstBits, in this case 1BCN1u

user43738: Having seen that yes blockchain.info no longer offers this service I was able to find only one other Block explorer that do offer the FirstBit lookup on addresses:
https://www.walletexplorer.com
https://www.walletexplorer.com/address/1BCN1ugdKdWd9pQ8Am9hMhtHZfmbXzxE8a?from_firstbits=1BCN1u
Hope this helps :)

user2229: Blockchain.info has APIs to generate and resolve firstbits.
Get firstbits,
http://blockchain.info/q/getfirstbits/1BCNEPySL4gzzjg8NNyNsQYJWYmZwpgaPF
Get address,
http://blockchain.info/q/resolvefirstbits/1paypal
http://blockchain.info/q/resolvefirstbits/1ebay
http://blockchain.info/q/resolvefirstbits/1google

78: <p>Input: any old Bitcoin address e.g. </p>

<p>1BCNEPySL4gzzjg8NNyNsQYJWYmZwpgaPF</p>

<p>Output: the FirstBits, in this case <strong>1BCN1u</strong></p>
 43738: <p>Having seen that yes blockchain.info no longer offers this service I was able to find only one other Block explorer that do offer the FirstBit lookup on addresses:</p>

<p><a href="https://www.walletexplorer.com" rel="nofollow noreferrer">https://www.walletexplorer.com</a></p>

<p><a href="https://www.walletexplorer.com/address/1BCN1ugdKdWd9pQ8Am9hMhtHZfmbXzxE8a?from_firstbits=1BCN1u" rel="nofollow noreferrer">https://www.walletexplorer.com/address/1BCN1ugdKdWd9pQ8Am9hMhtHZfmbXzxE8a?from_firstbits=1BCN1u</a></p>

<p>Hope this helps :)</p>
 2229: <p>Blockchain.info has APIs to generate and resolve firstbits.</p>

<p>Get firstbits,</p>

<p><a href="http://blockchain.info/q/getfirstbits/1BCNEPySL4gzzjg8NNyNsQYJWYmZwpgaPF" rel="nofollow">http://blockchain.info/q/getfirstbits/1BCNEPySL4gzzjg8NNyNsQYJWYmZwpgaPF</a></p>

<p>Get address,</p>

<p><a href="http://blockchain.info/q/resolvefirstbits/1paypal" rel="nofollow">http://blockchain.info/q/resolvefirstbits/1paypal</a></p>

<p><a href="http://blockchain.info/q/resolvefirstbits/1ebay" rel="nofollow">http://blockchain.info/q/resolvefirstbits/1ebay</a></p>

<p><a href="http://blockchain.info/q/resolvefirstbits/1google" rel="nofollow">http://blockchain.info/q/resolvefirstbits/1google</a></p>
