PoloDB is a library written in Rust that implements a lightweight MongoDB (opens in a new tab).


PoloDB aims to offer a modern alternative to SQLite, which is currently the almost exclusive option for client-side data storage. Although SQLite is an old and stable software, it lacks some modern features. That's why we developed PoloDB, which is NoSQL, supports multi-threading and multi-sessions, and retains the embedded and lightweight features of SQLite.


  • Simple and Lightweight
  • Easy to learn and use
    • NoSQL
    • MongoDB-like API
  • Cross-Platform
  • Multiple backends
    • Filesystem(WAL)
    • Memory
    • IndexedDB(WIP)


PoloDB designs an abstract layer for the computation and the store backend. It supports different backends naturally.

Filesystem Backend

With the filesystem backend, PoloDB stores data in a single file. All the data are saved persistently on the disk.

It's designed to be flexible, universal, and easy to be searched. All the data are encoded in bson format and stored in the PoloDB's lsm-tree format.

PoloDB uses WAL(write-ahead logging) to implement transactional writing and protect your data from program crashes.

Memory Backend

With the memory backend, all the data all stored in memory, making PoloDB a pure memory database.


Theoretically, PoloDB supports all platforms that the Rust compiler supports. But PoloDB is a personal project currently. Limited by my time, I have only compiled and tested on the following platforms:

  • macOS Big Sur x64
  • Linux x64 (Tested on Fedora 32)
  • Windows 10 x64