Open Source Spreadsheet
A spreadsheet stops being a spreadsheet the moment two people edit it and a third builds a report on top - then formulas, types, and relationships matter more than the grid, and the gap between a loose sheet and a real database is where data quietly rots. The open source options here span that range, from a calculating grid to relational tables with typed columns, views, and an API, keeping the data in a database you host and can query directly instead of a cell range trapped in someone's cloud.
NocoDB
Self-hostable no-code platform that turns any database into a spreadsheet interface
Teable
Spreadsheet-like no-code Postgres for building database apps and team workflows
APITable
API-oriented low-code spreadsheet for collaborative apps, automation, and embedded database views
Grist
Relational spreadsheet software that combines spreadsheet flexibility with database structure
ONLYOFFICE Docs
Collaborative online office suite for documents, spreadsheets, presentations, forms, PDFs, and diagrams
Baserow
Open source no-code database and app builder with AI, automations, dashboards, and self-hosting
LibreOffice
Free open source office suite with Writer, Calc, Draw, Impress, and broad document format support
EtherCalc
Web spreadsheet for real-time collaborative editing with self-hosting via Docker Compose or Cloudflare
undb
Open source no-code database and BaaS built on SQLite for local-first, self-hosted data management