I am looking for places to trade altcoins.

- Ideally, most cryptocurrencies from the coinmarketcap list: https://coinmarketcap.com/all/views/all/
- API access to bids data

The major platforms like BitStamp or BitFinex work with only a few pairs unfortunately.

Please post your suggestions on reliable marketplaces!

Yes, bitstamp has the websocket API and bitfinex has the `orderbook` API. Thanks for the tip!

We are going to release some really insightful tool for crypto traders soon.

Is there any service that can provide a live stream of all transactions for selected pairs on a certain marketplace?

Like, XRP/USD (price, amount, timestamp) values from bitstamp.net, etc
Basically the same data that BitStamp displays at their home page in "Live Trades" section. 

Or any websites that display the data that can be crawled?

We are working hard to build market analysis tools and such data is viable for our project.

I would add major tech blogs journalists contact lists:

https://reporters.io/r/ico
https://reporters.io/r/blockchain
https://reporters.io/r/cryptocurrency

I see extremely high level of redundancy as the bottleneck of Blockchain.

Now everyone keeps the history of all bitcoin transactions in local database. How big the decentralized db can get? Someone asked `why not create decentralized twitter` here - this is a good idea, but what about practical implementation? Everyone keeps the history of *all* tweets? Everyone has to download 100's of GB of data to see most recent tweets? It does not seem to be practically feasible.

I wonder if there are blockchain implementations that can bypass this limit.