Here are two that I use:

http://sdbs.db.aist.go.jp/sdbs/cgi-bin/direct_frame_top.cgi

http://webbook.nist.gov/chemistry/name-ser.html

For gases the most important database is HITRAN. It is hard to use but for gases it is very important. http://www.cfa.harvard.edu/hitran/

Exist number of commercial software which can make life easier. One of them you can get via contact to: http://www.neoplas-control.de/index.html

For residents of not "black listed contries" by US authorities: https://secure2.pnl.gov/nsd/nsd.nsf/Welcome

They are other sourses (for example NIST) but most of them are not relaible for gases.  

Yes,

link from David Jensen is popular.

http://webbook.nist.gov/chemistry/name-ser.html

thank u

My colleagues show me a new project. The project, seems to be, started in 2010

http://hitran.iao.ru/

Thank you

I would be interested in comparing spectra to one another. For example, you have a reaction A + B goes to C, and you have purchased pure C and a range of synthesised C's and you want to see which is the purist C ... a poor man's HPLC, if you like. Any ideas?

Dear Santosh,

This is what we do for IR and Electroluminescence images from silicon photovoltaics. Which is your main application? As you see, there are different sources of interest (gases, solids, semiconductors,...).

Best,

Marco

Sorry, I forgot the link in my previous reply:

Here we arecan:

https://www.sciencedirect.com/science/article/pii/S0038092X18307199

https://spectrabase.com/