UnQLite

Free plan APILinuxMacSelf-hostedWindows

What UnQLite is

UnQLite is a free, open-source, in-process NoSQL database engine with key/value and document-store interfaces. Applications read and write database files directly, so the engine does not require a separate server process. A complete database, including multiple collections, is stored in one ordinary disk file. It supports byte-array key/value data and JSON document storage through its embedded Jx9 scripting language, with JSON objects, arrays, and strings among the listed formats. The maker describes UnQLite as transactional and ACID, with serializable transactions designed to remain atomic through crashes and power failures. It offers on-disk and in-memory databases and a pluggable runtime storage engine. The core imposes no database size limit, though the underlying key/value store determines its own limit. Thread safety requires compilation with the UNQLITE_ENABLE_THREADS directive. C and C++ APIs are available, with documentation on registering C/C++ functions and constants for Jx9 scripts. Downloads include source code, a key/value-only package without the Jx9 document-store layer, documentation, and sample programs. UnQLite is released under the 2-Clause BSD license, and the maker offers a proprietary extension for databases encrypted with 128-bit or 256-bit AES.

Who it suits

UnQLite suits developers building applications that need embedded key/value or JSON document storage without a separate database server. Its self-contained library is also described as suited to embedded devices and applications running across computers with varied configurations.

What it does well

Runs in-process without a separate server process.
Stores a complete database in one ordinary disk file.
Supports byte-array key/value data and JSON documents.
Offers on-disk and in-memory database options.
Open-source under the 2-Clause BSD license.

What to know first

Thread safety requires the UNQLITE_ENABLE_THREADS compile-time directive.
The core’s unlimited-size claim depends on the underlying key/value store limit.
The AES encryption extension is proprietary.
Professional support is a paid service available on request.

Limits

The engine’s core imposes no database size limit, but the underlying key/value store has its own limit. Thread safety depends on compiling with the UNQLITE_ENABLE_THREADS directive.

Plans

Plan	Billed and limits	Price
UnQLite open-source software	2-Clause BSD license · downloadable source code	Free
Silver Sponsorship	$15K/Year · Sponsorship benefits listed by the maker	$15,000 a year
Gold Sponsorship	$50K/Year · Enterprise-level technical support · direct source-tree and core-developer access	$50,000 a year
Platinum Sponsorship	$100K/Year · Enterprise-level technical support · direct source-tree and core-developer access	On request

As unqlite.symisc.net lists them, read 8 Oct 2026. The maker's own page has the final word.

Getting started

Visit the UnQLite website.
Choose source code or the key/value-only package from the downloads page.
Use the C/C++ APIs to integrate the library into an application.
Use the Jx9 documentation if registering C/C++ functions or constants for scripts.

Verdict

Choose UnQLite if your application needs an embedded database with key/value or JSON document storage and direct file access. Look elsewhere if you need a separate server process, or if thread safety without a compile-time directive is essential.

Questions

Is UnQLite free and open source?

The open-source software plan is free and uses the 2-Clause BSD license. Sponsorship plans are also listed: Silver Sponsorship is $15,000 a year, Gold Sponsorship is $50,000 a year, and Platinum Sponsorship is $100,000 a year.

Does UnQLite require a database server?

No separate server process is required; applications read and write database files directly.

What data can UnQLite store?

It supports byte-array key/value data and JSON document storage through Jx9, including JSON objects, arrays, and strings.

Which platforms does it support?

The listed platforms are API, Linux, macOS, self-hosted, and Windows.

Is UnQLite thread-safe?

The library is thread-safe when compiled with the UNQLITE_ENABLE_THREADS compile-time directive.

What support and encryption options are available?

Public technical discussion and troubleshooting are directed to GitHub Issues; professional support is available as a paid service on request. A proprietary extension supports reading and writing databases encrypted with 128-bit or 256-bit AES.

Facts from UnQLite's own pages

Capacity: The FAQ says the UnQLite core imposes no database size limit and that the underlying key/value store determines its own limit. · unqlite.symisc.net, 8 Oct 2026
Data models: UnQLite supports byte-array key/value data and JSON document storage through the embedded Jx9 scripting language. · unqlite.symisc.net, 8 Oct 2026
Downloads: The downloads page lists source code, a key/value-only package without the Jx9 document-store layer, documentation, and sample programs. · unqlite.symisc.net, 8 Oct 2026
Integration: The maker provides C/C++ APIs and documents how to register C/C++ foreign functions and constants for use from Jx9 scripts. · unqlite.symisc.net, 8 Oct 2026
Intended use: The maker says the self-contained library is suited to embedded devices and applications that need to run across computers with varied configurations. · unqlite.symisc.net, 8 Oct 2026
License: UnQLite is open-source software released under the 2-Clause BSD license. · unqlite.symisc.net, 8 Oct 2026
Platforms: The ANSI C code is described as running on most platforms with a C compiler and is extensively tested on Windows, Linux, FreeBSD, Oracle Solaris, and Mac OS X. · unqlite.symisc.net, 8 Oct 2026
Purpose: UnQLite is an in-process, embedded NoSQL database engine that provides key/value and document-store interfaces. · unqlite.symisc.net, 8 Oct 2026
Security extensions: The maker offers a proprietary extension for reading and writing databases encrypted with 128-bit or 256-bit AES. · unqlite.symisc.net, 8 Oct 2026
Serverless: Applications read and write database files directly without a separate server process. · unqlite.symisc.net, 8 Oct 2026
Storage: A complete database with multiple collections is contained in a single ordinary disk file. · unqlite.symisc.net, 8 Oct 2026
Storage options: The maker lists both on-disk and in-memory databases and describes a pluggable runtime storage engine. · unqlite.symisc.net, 8 Oct 2026
Support: Public technical discussions and troubleshooting are directed to GitHub Issues, while professional support is available as a paid service on request. · unqlite.symisc.net, 8 Oct 2026
Thread safety: The library is thread-safe when compiled with the UNQLITE_ENABLE_THREADS compile-time directive. · unqlite.symisc.net, 8 Oct 2026
Transactions: The maker describes UnQLite as transactional and ACID, with serializable transactions designed to remain atomic through crashes and power failures. · unqlite.symisc.net, 8 Oct 2026

Where UnQLite stands on Freedom251

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