Structr

Structr is a generic low-code development and runtime platform built on graph technology. It is not tied to one use case and is meant for building fully custom applications, including web applications, graph-database-backed back ends, data-centric systems, middleware and integration components.

At its core Structr keeps both application components, such as schema, UI definitions, templates, scripts and workflows, and the application data in a graph database (Neo4j). That gives schema flexibility and expressive data modeling without join-heavy queries, and the schema can be represented as JSON Schema with import and export. A virtual file system manages files with custom metadata and can store binary content on external providers such as S3. Development happens in a web-based developer and admin UI that works as an integrated IDE.

The README is explicit about what Structr is not: it is not a prebuilt CMS, CRM or ERP, a website builder, or an industry template collection, but a set of building blocks for your own applications. The GitHub repository is a clone, and development and issue tracking have moved to gitlab.structr.com. The license is listed as Other, and the topics mention GraalVM polyglot programming.