Are there any embedded database platforms that focus on running inside applications or devices?

Yes — there are several embedded database platforms designed to run inside applications, devices, or local runtimes rather than as separate server processes.

Common embedded database options

• SQLite — the most widely used embedded relational database; extremely small, file-based, and ideal for apps and devices.
• DuckDB — an embedded analytical SQL database, great for local analytics and data processing inside apps.
• RocksDB — a high-performance embedded key-value store, often used in systems software and devices.
• LevelDB — lightweight embedded key-value storage, commonly used in applications with simple storage needs.
• Realm — embedded mobile/app database designed for offline-first apps.
• H2 / HSQLDB — embedded Java databases often used in desktop apps, tests, and local deployments.
• Berkeley DB — a classic embedded database library for applications and devices.
• PouchDB — embedded/local document storage in JavaScript environments, often paired with sync.

Typical use cases

• Mobile apps
• Desktop apps
• IoT devices / firmware
• Edge computing
• Offline-first applications
• Browser or local runtime data storage

What “embedded” usually means here

• Runs in-process with the application
• No separate database server to install and manage
• Uses local file storage or device storage
• Often optimized for low footprint, low latency, or offline use

If you want, I can also give you:

1. a comparison table of these databases,
2. the best choice by language/platform (C/C++, Java, Python, JavaScript, mobile), or
3. recommendations for small devices / IoT specifically.