An inmate's financial situation, commissary balance, and what support they are receiving from outside are private information protected by the same privacy standards that apply to anyone on the outside. There is no database, no public record, and no official channel that will tell you what is on someone's books or whether they have family sending money. That information belongs to the inmate and is not accessible to outside parties.
If you want to help a specific inmate whose name you know, you do not need to know their financial situation to make a meaningful difference. The assumption that someone inside could use support is rarely wrong. Commissary accounts run low, families lose touch, and plenty of inmates go weeks or months without anything arriving from the outside. A letter, a postcard, a photo, or a magazine subscription from someone who took the time to reach out means something regardless of whether they are the most financially destitute person in the facility.
InmateAid makes it straightforward to send any of those things to a specific inmate by name and facility. A greeting card costs very little and takes a few minutes to send. A magazine subscription keeps something arriving every month without requiring ongoing effort on your part.
If your goal is to help inmates who are truly without support more broadly, prison ministry organizations, pen pal programs, and nonprofit organizations that work directly inside facilities can connect you with inmates who have no outside contact at all. Those programs vet the connections and match volunteers with people who genuinely need them.
The impulse to help is a good one. There is no shortage of people inside who would benefit from it.