It is also good for in-process data caching.
Most Widely Deployed SQL Database Engine
"Since SQLite is used extensively in every smartphone, and there are roughly 3.5 billion smartphones in active use, each holding hundreds of SQLite database files, it is seems likely that there are over one trillion SQLite databases in active use. Most Widely Deployed Software Module of Any Type?"
Well-Known Users Of SQLite
SQLite in 2018: A state of the art SQL dialect
"SQLite is an undervalued database—some people even believe it is a toy database that is not suitable for production use. In fact, SQLite is a very solid database that can handle terabytes of data.”
performance - What is a realistic, real-world, maximum size for a SQLite database? - Software Engineering Stack Exchange"An SQLite database is limited in size to 140 terabytes (247 bytes)"
SQLite's code is hosted with Fossil, a distributed version control system that is itself built upon an SQLite database.
Fossil is a distributed version control system, bug tracking system and wiki software server for use in software development created by D. Richard Hipp.
Fossil (software) - Wikipedia