Firm-level Financials
Very few, if not none, free data available
Easier if the company is listed, even easier if listed in developed country due to regulation-based information. Before heading into the institutional paperworks for paid channel(s) access, have a look on this guide on yahoo finance API, the tool (scraping via Python and/or other programme languages) should be able to get a hand on some firm-level data at daily interval.
Paid channels
Both ORBIS and Capital IQ are very capable platforms.
Capital IQ does have convenient feature in excel plug-in where you could cherry pick data and output format. The plug-in, however, supports only windows as of now. Read more: a nice manual found online by Larry Schrenk
Last note: In my previous project, CIQ is more capable in identifying firms by ticker and ISIN from varies format, e.g. searching for Tencent Holdings Limited (SEHK:700) and input “700”, CIQ would fetch “700” from all exchanges, while ORBIS would return nothing as their format recognizes only “00700” for SEHK listing.
In addition, CIQ can also fetch the firm behind a corporate bond issuance with a higher identifying/matching/successful rate than ORBIS, given the bond ISIN. *Though you do need to check carefully on the returning results.
Corporate bonds
Refinitiv Eikon is the best I have encountered. You could find data available by individual bond covering an extensive period of time and countries.
Guide can be found from the Eikon search portal: Fixed. Income -> Bonds -> Corporate
Beginner guide by Toronto U found on Google
S&P Capital IQ also provides the same issuance-level data. In similar to Refinitiv, you will need an excel plug-in to generate the result, which only works on window platform. For guide, google: “S&P Capital IQ Excel Plug-in Manual Larry Schrenk”. (It says NOT for redistribution and I don’t want to get in trouble.)
I have not come across any API integration for either Refinitiv or Capital IQ yet.
Untested FREE channel
Check out this Tweet: Someone built a Python-based platform mimicking Bloomberg terminal.