DATA low cost Web Services
http://disktrading.is99.com/disktrading/
(really low cost, but according to my experiences the service and support is not very stable. Anyhow, if you get the data, you don't need anything more)
http://www.backtestdata.com/
(relatively low cost - you can export to CSV and use as you need)
http://www.tickdatamarket.com/
(a little expensive, but there is almost everything)
http://pitrading.com/historical-data.html
https://quantquote.com/. They are very low cost and I've used them before for historical 1-min data. They do tick data, too. Their prices are very low, but their service is not great.
http://technologies.teletrader.com/ TeleTrader has a lot of data and a REST style web service on top of it (as well as various other APIs).
CQG has a web socket API based on Google protocol buffers for futures data. Cost is $25 per month plus exchange fees if you want realtime data.
Reverse engineer available mt4 mt5 brokers that include futures tick data (free)
Iq feed (the best low cost actually this was recommended by a friend who is a master at stock trading ) me I'm a forex man myself but good luck
Getting an account at Interactive Brokers is not very cheap (20k) but if you pay the database monthly fees they have one of the most comprehensive databanks worldwide with minimal cost per month
https://www.quantopian.com to skip the effort of building an algo trading platform.
www.TickData.com. Has tick-by-tick quotes & trades for equities, futures, options, forex and more. Also have an API / Web Service so you can request data programmatically. Looks looks like really professional service, but does not look so low-cost :) as it is required by Corneliu. It can cost serious amount of money (in thousands) to buy data for 10 instruments / 10 years history, which is a minimum "starting" package for any backtesting…
Tradier.com. good place to start and you get the ability to access mordern APIs.
Eoddata
DTN/IQ ==http://www.dtnprogressivefarmer.com/dtnag/====…==
Tradier.com
