This website visualizes the internal structure of the database file used in my own RDBMS (RocketSQL).
The database file consists of interleaved 512B pages, where each page represents a node in some B+ Tree structure. Each table stored in the database is stored in one B+ Tree. B+ Tree nodes have two types: interior and leaf nodes. Interior nodes contain keys (PKs of the table's rows) and pointers to other nodes/pages. Leaf nodes contain PKs and their corresponding rows. This approach is called index-organized tables and is popular in RDBMSs like SQLite and MySQL (InnoDB).
Refer to RocketSQL's README to know exactly what type of SQL statements are supported and gain a deeper understanding of the file format.
This file format borrows greatly from SQLite's File Format.
This project is heavily inspired by SQLite's File Format Viewer.
Also, this was 90% vibe-coded. I suck at frontend.