user62633: I would like to write small paper supported by Blockchain stats.
Could you tell me how to access blocks chain remotely via GUI to make a query ?
Blockchain's size is 159GB as of today, so download is heavy.
Ok, I can study block headers only to limit overheads.
Do you know how to download or access blockchain headers as mySQL database ?
How to access Blockchain remotely for statistics study ?

user51948: As you mention in your comments, blockchain.info can provide this information.
You can get a raw block in JSON format using the /rawblock/ links, for example:
https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516
Then you can also get it as the hex-encoded raw block by adding ?format=hex to the url:
https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516?format=hex
Hope that's what you are after :)
EDIT: Oh, just re-read your comment, you want just the headers? In that case you probably can't use blockchain.info, you could try BlockCyhper instead:
For example: https://api.blockcypher.com/v1/btc/main/blocks/294322
You can find more info about their API here: https://www.blockcypher.com/dev/bitcoin/#blockchain-api

62633: <p>I would like to write small paper supported by Blockchain stats.
Could you tell me how to access blocks chain remotely via GUI to make a query ?</p>

<p>Blockchain's size is 159GB as of today, so download is heavy.</p>

<p>Ok, I can study block headers only to limit overheads.</p>

<p>Do you know how to download or access blockchain headers as mySQL database ?</p>

<p>How to access Blockchain remotely for statistics study ?</p>
 51948: <p>As you mention in your comments, blockchain.info can provide this information.</p>

<p>You can get a raw block in JSON format using the /rawblock/ links, for example:
<a href="https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516" rel="nofollow noreferrer">https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516</a></p>

<p>Then you can also get it as the hex-encoded raw block by adding <code>?format=hex</code> to the url:
<a href="https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516?format=hex" rel="nofollow noreferrer">https://blockchain.info/rawblock/0000000000000000008d49f25f7dd5d3704575a348e030a1d2e5f396b3e80516?format=hex</a></p>

<p>Hope that's what you are after :)</p>

<p>EDIT: Oh, just re-read your comment, you want <em>just</em> the headers? In that case you probably can't use blockchain.info, you could try BlockCyhper instead:</p>

<p>For example: <a href="https://api.blockcypher.com/v1/btc/main/blocks/294322" rel="nofollow noreferrer">https://api.blockcypher.com/v1/btc/main/blocks/294322</a></p>

<p>You can find more info about their API here: <a href="https://www.blockcypher.com/dev/bitcoin/#blockchain-api" rel="nofollow noreferrer">https://www.blockcypher.com/dev/bitcoin/#blockchain-api</a></p>
