Open source intelligence went from a niche tradecraft term to a mainstream discipline in about five years. Journalists use it, financial investigators use it, human rights researchers use it, and every defence and security organisation has a team doing it. The acronym is now the name of a field.
OSINT.org is the exact term on the extension that field actually uses. Look at where the serious OSINT work gets published: research collectives, verification outfits, transparency nonprofits, training organisations. They’re almost all .org, because the credibility of the work depends on not looking like a vendor.
It would carry a training academy, a tools directory, a methodology reference, a research collective, or a professional association. Any of those would gain instant standing from the address alone. For a commercial platform it works too, as the neutral community-facing front for a paid product.
This is the category-defining term for a discipline that’s still growing, and there’s exactly one of it on .org.
Serious offers considered.