All of this is verified by the automated tests using special test harnesses which simulate system failures. Transactions are ACID even if interrupted by system crashes or power failures. SQLite responds gracefully to memory allocation failures and disk I/O errors. An automated test suite runs millions and millions of test cases involving hundreds of millions of individual SQL statements and achieves 100% branch test coverage.
Most of the SQLite source code is devoted purely to testing and verification. SQLite is very carefully tested prior to every release and has a reputation for being very reliable. Nevertheless, performance is usually quite good even in low-memory environments. SQLite generally runs faster the more memory you give it. There is a tradeoff between memory usage and speed. SQLite can also be made to run in minimal stack space (4KiB) and very little heap (100KiB), making SQLite a popular database engine choice on memory constrained gadgets such as cellphones, PDAs, and MP3 players. And some compiler optimizations such as aggressive function inlining and loop unrolling can cause the object code to be much larger.) If optional features are omitted, the size of the SQLite library can be reduced below 300KiB. With all features enabled, the library size can be less than 350KiB, depending on the target platform and compiler optimization settings. Think of SQLite not as a replacement for Oracle but as a replacement for fopen() These features make SQLite a popular choice as an Application File Format.
The database file format is cross-platform - you can freely copy a database between 32-bit and 64-bit systems or between big-endian and little-endian architectures. A complete SQL database with multiple tables, indices, triggers, and views, is contained in a single disk file.
SQLite reads and writes directly to ordinary disk files. Unlike most other SQL databases, SQLite does not have a separate server process. SQLite is an embedded SQL database engine. SQLite is currently found in more applications than we can count, including several high-profile projects.
The code for SQLite is in the public domain and is thus free for use for any purpose, commercial or private. SQLite is a in-process library that implements a self-contained, serverless, zero-configuration, transactional SQL database engine.