I have read a little about blockchains and found there is lot of blockchain npm libraries available.
How can I take benefit of the bitcoin blockchain to authenticate documents : to obtain a proof a document has not been falsificated.
Any clues, suggestions, ideas and remarks are welcome.
If you are looking for a way to certify the existence of an image, I'd suggest taking at OpenTimestamps. OpenTimestamps collects documents to timestamp and batches them in such a way that they use only minimal space in the blockchain, but still gain the advantages of using the Bitcoin blockchain.
If on the other hand you are looking to track ownership of assets, then I suggest looking into the native assets of Elements Project or Colored coins.
I would strongly suggest attempting to build a new scheme on top of an existing blockchain if one of these suggestions fits your use-case.
(disclaimer: my employer is a contributor in the Elements Project)